University of Veterinary Medicine Hannover Institute of Physiology and Cell Biology
Effects of vernal ration and environment change from a total mixed ration to a rotational grazing system with moderate concentrate feed supply on performance, energy
metabolism, rumen physiology and immune system of dairy cows in the midlactation
INAUGURAL – DISSERTATION
submitted in partial fulfillment of the requirements for the degree Doctor Natural of Sciences
- Doctor rerum naturalium - (Dr. rer. nat.)
by
Julia Hartwiger Leinefelde
Hannover, Germany 2019
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Scientific support: 1. Prof. Dr. Gerhard Breves
Institute for Physiology and Cell Biology; University of Veterinary Medicine Hannover, Germany
2. Prof. Dr. Pablo Steinberg
Max Rubner-Institut, Federal Research Institute of Nutrition and Food, Karlsruhe, Germany
3. Prof. Dr. Dr. Sven Dänicke
Institute of Animal Nutrition; Federal Research Institute for Animal Health, Friedrich-Loeffler-Institut,
Braunschweig, Germany
1st Evaluation Prof. Dr. Gerhard Breves Prof. Dr. Pablo Steinberg Prof. Dr. Dr. Sven Dänicke
2nd Evaluation Prof. Dr. Karl-Heinz Südekum
Date of final exam: October 17, 2019
Sponsorship: This thesis has been sponsored by the “Niedersächsisches Ministerium für Wissenschaft und Kultur” within the scope of the research project “Systemanalyse-Milch”.
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Parts of this thesis have been published previously in:
• Animals Published by MDPI AG, Basel, Switzerland
I. Hartwiger, J.; Schären, M.; Potthoff, S.; Hüther, L.; Kersten, S.; von Soosten, D.;
Beineke, A.; Meyer, U.; Breves, G.; Dänicke, S. Effects of a Change from an Indoor-Based Total Mixed Ration to a Rotational Pasture System Combined With a Moderate Concentrate Feed Supply on Rumen Fermentation of Dairy Cows. Animals 2018, 8, 205.
https://doi.org/10.3390/ani8110205
II. Hartwiger, J.; Schären, M.; Gerhards, U.; Hüther, L.; Frahm, J.; von Soosten, D.;
Klüß, J.; Bachmann, M.; Zeyner, A.; Meyer, U.; Isselstein, J.; Breves, G.; Dänicke, S.
Effects of a Change from an Indoor-Based Total Mixed Ration to a Rotational Pasture System Combined with a Moderate Concentrate Feed Supply on the Health and Performance of Dairy Cows. Animals 2018, 8, 169.
https://doi.org/10.3390/ani8100169
• Veterinary Sciences Published by MDPI AG, Basel, Switzerland
III. Hartwiger, J.; Schären, M.; Frahm, J.; Kersten, S.; Hüther, L.; Sauerwein, H.; Meyer, U.; Breves, G.; Dänicke, S. Effects of a Change from an Indoor-Based Total Mixed Ration to a Rotational Pasture System Combined with a Moderate Concentrate Feed Supply on Immunological Cell and Blood Parameters of Dairy Cows. Submitted for Veterinary Sciences 2019, 6, 47.
https://doi:10.3390/vetsci6020047
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To my family
(Sunrise over the pasture; Own image file)
„Wille ist ein Muskel, der trainiert werden will.“
(Unbekannt)
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VII
Table of contents
List of abbreviations ... VIII
1 Background ... 1
1.1 General introduction ... 1
1.2 Characteristics of pasture feed and its effect on dry matter intake ... 4
1.3 Effects of feeding supplements during the grazing season ... 6
1.4 Effects of different grazing systems on the animal ... 8
1.5 Effects of grazing on rumen fermentation ... 10
1.6 Effects of the genetic variation on grazing ... 13
1.7 Housing conditions according to welfare and behavior ... 15
1.8 Effects of transition to pasture on immune-related parameters ... 16
2 Hypotheses and objectives ... 18
3 Effects of a change from an indoor-based total mixed ration to a rational pasture system combined with a moderate concentrate feed supply on the health and performance of dairy cows ... 19
4 Effects of a change from an indoor-based total mixed ration to a rotational pasture system combined with a moderate concentrate feed supply on rumen fermentation of dairy cows ... 44
5 Effects of a change from an indoor-based total mixed ration to a rotational pasture system combined with a moderate concentrate feed supply on immunological cell and blood parameters of dairy cows ... 70
6 Discussion ... 90
6.1 General summary of the three scientific publications ... 90
6.2 Principal component analysis of the data of paper 1 and 3 ... 93
7 Summary ... 98
8 Zusammenfassung ... 104
9 References ... 111
10 Affidavit ... 122
11 Acknowledgements ... 123
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List of abbreviations
(accounts for chapters 1. Background, 2. Hypothesis and Objectives, and 6. Discussion) ADF Acid Detergent Fiber
BHBA Beta-Hydroxybutyrate
BW Body Weight
CG Confinement Group
DMI Dry Matter Intake
FFS-AT Fatty Acid Absorption Test
HA Herbage Allowance
HF Holstein Friesian LPS Lipopolysaccharide NEB Negative Energy Balance NEFA Nonessterified Fatty Acids NDF Neutral Detergent Fiber
PG Pasture Group
SARA Subacute Ruminal Acidosis TMR Total Mixed Ration
VFA Volatile Fatty Acid
WSC Water Soluble Carbohydrates
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1 Background
1.1 General introduction
Thousands of years ago, the domestication of ruminants by humans aimed at acquiring an easily available source of milk and meat. The pasture systems were first applied based on the observation that ruminants showed the nutritional behavior to feed themselves by extended grazing. Especially cattle are in general well adapted to pasture conditions because of their special anatomical and physiological characteristics (ENGELHARDT VON et al., 2015).
However, due to economic reasons and the demand for a higher milk production a paradigm shift to indoor feeding systems evolved. Development towards high-input and high-output systems, which was achieved due to increasing concentrate based TMR rations opposed to pasture grazing (KNAUS, 2016). In conclusion, as cattle in general and cows in particular are nowadays phenotypically and genetically so different from their archetype, research needs to be done in regards to a smooth renaissance of pasturing. In case of seasonal pasturing, particularly investigating the consequences of the transition from confinement to pasture after winter indoor feeding is necessary.
Grazing cows are an important part of the landscape all over the world. The decision for pasture housing is depending on different aspects such as soil and climate conditions, land availability, lactation stage and nutritional needs, farm management, socioeconomic factors and cultural aspects as well as the different breeds of the animals (VAN VUUREN AND VAN DEN POL, 2006, EFSA, 2015). Especially the intensification of dairy housing, precision feeding and genetic changes towards improvement of milk production have led to a decline in grazing access (KENNEDY et al., 2003) over the last decades. However, grazed grass is the cheapest source of nutrients for dairy cows (DILLON et al., 2005). DILLON et al. (2005), DILLON (2007) observed the relationship between milk production costs and the proportion of grazed pasture in the ration on an international scale (Figure 1). The figure shows that countries such as New Zealand, Australia and Ireland have the highest proportion of grazed pasture in cows’ rations and the lowest costs for milk production. Germany can be found in the middle of the range.
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Figure 1. Relationship between total costs of production and proportion of grazed pasture in cows ration. (Source:
DILLON et al. (2005))
Pasture farming is declining despite reduced costs through increased pasture utilization in dairy cow diets and even though pasturing is perceived favorably as enhancing the health and welfare of dairy cows (BLACK and KRAWCZEL, 2016, ARNOTT et al., 2017).
HANRAHAN et al. (2018) described different factors in their study associated with profitability in pasture-based systems of milk production which states that grazing needs an optimal management system.
VAN VUUREN and VAN DEN POL (2006) discussed more and different reasons influencing the decision for grazing. Amongst others, grazing depends on the region. In Europe, for example modern large-scale farms with increased herd size of high-yielding dairy cows need controlled conditions for a high efficiency. Other reasons for a decrease of grazing are less available area around the stable in relation to herd size, more technique like automatic milking, the need to reduce mineral losses and also labor efficiency. A report of REIJS et al. (2013) showed that 30 to 100% of the farms in the Northwest of Europe let their cows graze, whereas in Southern and Eastern Europe the trend to a zero grazing system is predicted until 2025.
Depending on the management system of the farmer pasture access can be practiced differently (REIJS et al., 2013, EFSA, 2015):
• All year grazing: at least 300 days/year (Azores, Ireland, Southern Italy)
• Extended grazing: 120-300 days/year (the UK, Sweden, Denmark, the Netherlands, Germany, France)
• Restricted grazing: periodically 15-120 days/year (Austria, Switzerland, France, Italy)
• Zero – grazing: null or very exceptional time on pasture
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WAGNER et al. (2018) concluded that grazing enhanced cow’s welfare during the summer, but also stated like HANRAHAN et al. (2018) that the management of pasture systems played an important role to guarantee beneficial effects.
In the German state Lower Saxony the decrease of grazing cows has led the Ministry of Science and Culture to fund a research project called “Systemanalyse Milch – Verbundprojekt zur Weiterentwicklung von Milchviehhaltung in Niedersachsen”: “System analysis – Cooperative research project for the development of dairy farming in Lower Saxony.”
(www.systemanalyse-milch.de). For five years, advantages and disadvantages of the milk production during confinement and pasture housing systems were investigated in nine different modules. The individual aspects of production were examined in the following thematic areas:
animal health and well-being, udder health, parasitology, feed production and nutrient management, rumen health and animal nutrition, sustainability, business administration and consumer acceptance. Aim of the research was to advice both the government and the dairy industry. The presented results of this thesis have been collected for three years being the second part of one of the nine modules of the named project.
In the first subproject the influence on the animal during transition from an indoor-based TMR to a full-grazing system combined with low amounts of concentrate supply was shown to result in an energy deficiency and a compromised milking performance of high yielding Holstein cows (SCHÄREN et al., 2016a). The alterations in various metabolic parameters were also reflected in different rumen variables (SCHÄREN, 2016, SCHÄREN et al., 2017).
Changes of rumen content, papillae surface area, microbial population, fermentation profile and mean rumen pH were documented during the first weeks on a full grazing ration. At the end of the trial, metabolism parameters and rumen variables seemed stabilized. However, during the adaption SCHÄREN (2016) could not exclude a possible risk for rumen health. In summary, the results showed that the amount of concentrate was on the one hand too low to face the observed limitation of energy but on the other hand the high content of fermentable carbohydrates increased the shift towards critical rumen pH range. Therefore, the aim of the present experiment was to examine the efficacy of a higher concentrate feed supply in order to facilitate the adaptation process and to alleviate the energy deficiency considering rumen health. For this, the range of the data was extended, collecting more information concerning behavior adaptations, energy metabolism and immunological parameters.
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1.2 Characteristics of pasture feed and its effect on dry matter intake
An adequate intake of feed is an important parameter to realize high milking performance in dairy cows (BARGO et al., 2002, KENNEDY et al., 2003, DOHME-MEIER et al., 2014).
Especially continuous housing offers the possibility to manage and provide a consistent feed ration to high yielding cows. However, pasture grazing involves different problems. Especially the low intake on pasture differs to the conventional intake of TMR in confinement (KOLVER and MULLER, 1998, BARGO et al., 2002, SCHÄREN et al., 2016a).
The intake rate of grazing ruminants can be affected by factors either linked to the animals or to the pasture quality, dependent on environmental and management components (MOORE and UNDERSANDER, 2002) (Figure 2).
Figure 2. Variables influencing DMI on pasture by ruminants (Own, schematic representation based on DILLON (2007))
Compared to ensiled feed supplied during confinement the chemical composition of grass differs in numerous parameters with several effects on the animal. Vernal high-quality pasture generally exhibits a high content of fast fermentable carbohydrates. Especially in cells of growing plants the proportion of mono- and polysaccharides are high, whereas the proportion of structured carbohydrates is low (STEINWIDDER and WURM, 2005, STEINWIDDER and STARZ, 2015). Additionally, during the day and dependent on the light intensity and photosynthesis the amount of sugar is variable (UEDA et al., 2016). In general, the energy density of grass is comparable with concentrate feed. Both in combination present a major challenge for rumen fermentation which underlines the importance of a well-planned concentrate supply during grazing season, having regard to rumen health. Depending on season, plant growth and age cell walls increase the lignification of plant tissue and increase the
DMI on Pasture
• Climate
• Soil type Enviroment
• Genotype
• Milk yield
• Live-weight Animal factor
• Sward structure
• Sward type Plant factor
• Herbage allowance
• Grazing intensity, stocking rate
• Supplementation (Concentrate, forage) Management
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retention time of the forage in the rumen (STEINWIDDER and WURM, 2005, STEINWIDDER and STARZ, 2015). Apart from this, the proportion of dry matter in pasture grass is low, which has a depressive effect on intake level because the high volume of water in the plants prevents further intake (DECRUYENAERE et al., 2009). Sward species composition of pasture can also influence its dry matter intake (DMI). It has been shown, that DMI and milk production can increase when the proportion of legumes (white clover) is high compared to pure grasses (JOHANSEN et al., 2018).
Environmental factors like climate and soil condition influence DMI as well. Climate factors are important for pasture growing and digestibility of the plants. WILSON et al. (1991) concluded that high temperatures increased intensity of lignification with consequences on the digestibility of grass. Among the influence of climate on pasture growing, the impact of heat stress and direct influence of external conditions (rain, wind) also make an impact on DMI behavior (GORNIAK et al., 2014, SCHÄREN et al., 2016a).
Herbage allowance which is defined by the weight of herbage cut above a sampling height can be one key factor, which might positively influence DMI and milk yield but negatively the efficiency of grazing (BAUDRACCO et al., 2013). Feed intake at high herbage allowance is influenced by the nutritional factor (feed quality) and by the rumen capacity (BAUDRACCO et al., 2010). High concentrations of neutral detergent fiber (NDF; which is a measure of cell wall content) at high herbage allowance influence rumen fill; that’s why intake is limited due to animal size and therefore rumen volume and it is, by contrast, controlled at low NDF concentrations due to physiological energy demands of the animal (HADGU, 2016).
GIBB et al. (1997) documented the effect of sward height and its influence on grazing behavior and intake rate. In their experiment a maximum herbage intake was observed at a mean sward height about 7 cm.
The number of animals per unit of land is defined as stocking rate. If the stocking rate on pasture is too high the time period for regrowing of the plants is low and vice versa. If the time for regrowth is too short the intake per bite decreases, whereas a low stocking rate leads to feed selection of herbage and loss of pasture quality (DILLON, 2007, ROCA FERNANDEZ and GONZALEZ RODRIGUEZ, 2013).
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We can conclude that plant, environment and management factors can influence DMI on pasture in different ways. Especially fluctuations in chemical composition can be partly managed by offering cows supplemental feed (chapter 1.3).
1.3 Effects of feeding supplements during the grazing season
In general, in grazing systems, pasture DMI is insufficient to meet the energy needed for milk production (BARGO et al., 2003, KENNEDY et al., 2003, DOHME-MEIER et al., 2014, SCHÄREN et al., 2016a). VAN VUUREN and VAN DEN POL (2006) reported that grazing delivered enough energy and protein to meet the requirements for a milk production of 22 to 26 kg/day. Cows with a higher production need concentrate supplementation to meet their relatively high energy and protein requirements. The efficiency of concentrate is expressed as kg increase in milk production per kg increase in concentrate DM intake. Especially in early lactation, grazing without supplements does not fulfill energy requirements to build up body reserves (ZBINDEN et al., 2016). During late lactation, REID et al. (2015) then again did not find a difference between milk production offering 3 or 6 kilogram of concentrate additionally per cow and day during on pasture.
HILLS et al. (2015) reported in their review that providing balanced supplements increased the intake of nutrients and therefore milk production. MULLER (2003) stated that grazing cows required more energy because of a higher physical activity compared to indoor housing cows which means they need an extra concentrate feed supply of approximately.
MCEVOY et al. (2008) examined that concentrate supply was used to extend grazing during seasons when the quality of grass decreases, or to ensure sufficient energy intake to maintain cows in early lactation. On the other hand, when offering more pasture than the herd requires (grazing pressure) supplying concentrate is questionable and its influence on milking performance is only marginally (BARGO et al., 2002).
Increasing concentrate supplementation can be related to the decrease in herbage DM intake (pasture-concentrate substitution), but conclusive results about the effects of the amount of supplementation and type of concentrate on the substitution rate are missing. From the review of BARGO et al. (2003) it can be concluded that the substitution rate increased with increasing pasture allowance (chapter 1.4). Furthermore, when herbage allowance is high the milk production reaches a plateau at 4 kg concentrate feed supplementation; but with restricted pasture allowance, a linear response up to 6 kg of concentrate feed was found (DELABY et al.,
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2003). Some authors reported a great and immediate milk response to supplements in early lactation which, however, decreased again thereafter (KELLAWAY and HARRINGTON, 2004). SILVA et al. (2017) concluded that the supply of moderate amounts of concentrate (2 kg per day) increased the production performance without affecting forage intake.
Another important fact is, that cow strains respond differently to concentrate feed supplementation (HEUBLEIN et al., 2017). KOLVER and MULLER (1998) stated for example that Holstein Friesian cows are less suited for grazing systems and especially without additional concentrate supply. Therefore, feeding concentrate or not is likewise dependent on the genetic merit of the animals.
Main sources of energy supply are carbohydrates from grains and concentrates.
Concentrate types differ in their effect on rumen fermentation and milk production. (KHALILI and SAIRANEN, 2000) found better results when feeding a complete concentrate feed mixture compared to barley supplemented as individual feedstuff.
Another option besides concentrate supply is the use of mixed rations as one part of the total daily ration together with different access time to pastureland. The study of BARGO et al.
(2002) showed that access to TMR increased the milk response up to 17%. RUIZ-ALBARRAN et al. (2016) concluded that silages (maize or grass) had a greater effect on milk yield, DMI and energy intake than an increase in herbage allowance. The positive effect on milk yield and energy intake was not confirmed by SCHÄREN et al. (2016a). During transition to pasture (feeding TMR in confinement combined with increasing time on pasture access) a decrease in milk yield, bodyweight and further parameters was observed in their investigation.
In general, feeding concentrate or mixed ration depends on access time on pasture. Farmers who practice restricted grazing per day combine this often with TMR feeding during time in confinement, whereas farms with fulltime pasture systems often use concentrate supplementation (STEINWIDDER and STARZ, 2015). Additional feeding plays an important role to supply lactating cows with enough energy. In particular, the transition time challenges the rumen digestion as there is no continuity due to the daily changing feed intake of the separate components and further health consequences can thus possibly occur. Furthermore, concentrate is mostly fed during milking in confinement, which leads to a short time pH drop.
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1.4 Effects of different grazing systems on the animal
Pasture in early growing stage provides herbage with low fiber content, but generally high sugar and high moisture content, that means a so called high-quality pasture (AGENÄS et al., 2002). To ensure an adequate energy supply for and high milk output of the cows different feeding systems can be distinguished (VAN VUUREN and VAN DEN POL, 2006):
• Unrestricted grazing
• Restricted grazing, usually during the day
• Zero-grazing, ration of fresh grass
• Zero-grazing, ration of ensiled grass
A pasture-based system can vary between those for which pasture is used as the primary feeding source and systems in which primary TMR is fed and pasture is used as supplemental forage. Each system has their advantages and disadvantages depending on the farm conditions.
The choice for fulltime grazing offers different opportunities and the farmer’s decision mostly depends on external conditions, like time for management and investment. There are several systems or techniques which could be considered. The most practiced systems are the rotational and the continuous grazing system. According to model calculations rotational grazing systems are more efficient (CHEN and SHI, 2018). On the other hand, the results of (PULIDO and LEAVER, 2003) showed no evidence in higher milk yield or live weight and BCS, comparing a continuous and a rotational grazing system. In Table 1 the two most known systems are compared.
Table 1. Comparison of a rotational and continuous grazing systems (STEINWIDDER and STARZ, 2015).
Pasture system Practical implementation Advantages Disadvantages Rotational grazing
(starting grass height max. 15 cm, moving by 5 cm)
Cows are moved around between the paddocks, depending on grass height or grazing quality
• Controllability of food range
• Forage is utilized more completely
• High costs for pasture management
• Frequent changing grass quality Continuous grazing
(continuously grass height 5-6 cm)
Cows are in the same paddock usually for the entire grazing season
• Less time-consuming
• Less pasture management
• Constant quality of feed
Optimal grass growth difficult to manage
The main difference between both systems is the grass height and therefore the chemical composition, the herbage allowance and also the influence of a frequent rotation. Sward height plays an important role, it relates to bite size and eating time (GIBB et al., 1998). GIBB et al.
(1997) investigated the influence of pasture height on feed intake rate. The results showed that
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a decrease in sward height led to an increase in grazing time. The cow can compensate this phenomenon only to a certain degree by a decrease of ruminating time and time for other activities. Daily herbage allowance is described as the quantity of daily herbage cut above a specific height offered per cow (ROCA FERNANDEZ and GONZALEZ RODRIGUEZ, 2013). A higher grass height in a rotational grazing system results in a high daily herbage allowance, which might be a useful grazing management tool for improving profitability and sustainability. If the grazing height is high, the amount of feed per bite increases (STEINWIDDER and STARZ, 2015), whereas very short pasture heights makes it difficult for the animal to eat sufficient quantities of DM (DILLON, 2007). However, this does not mean that a higher herbage allowance is always the best choice. MERINO et al. (2018) observed in their study that a restriction on the daily herbage allowance ensured a higher level of herbage utilization and milk output per hectare. The most important factor is the optimal management of the pasture in order to ensure high quality composition.
In Figure 3 the association between pasture height and changing chemical compositions is shown. Especially the grass height differs between a continuous (5-6 cm) und rotational grazing system (up to 15 cm). As pasture matures, the proportion of leaf, protein and energy decreases, whereas the proportion of stem, fiber and lignin increases and therefore pasture feed intake decreases (UNKNOWN, 2016). The challenge with a rotational grazing system is not to miss the optimal grass height and to optimally manage the different areas for rotation.
Figure 3: Changes in pasture quality components during different growth stages (Own, schematic representation based on UNKNOWN (2016)).
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The management of rotation depends on the DMI of the cows and the time of grass growth and recovering of the various pasture areas. The study of ABRAHAMSE et al. (2008) documented different types of frequent pasture rotation. They observed an improvement in milk production, especially when offered pasture was high and a daily rotation frequency or one of every four days was practiced. The study of VERDON et al. (2018) tested a frequency of two times and seven times per day and its impact on grazing time, intake and milk yield. Their results showed no advantages of a higher frequency of rotation on the mentioned parameters.
They concluded that the success of an intensive grazing system depended on management and keeping natural behaviors.
The research of COPPA et al. (2015) underlines the impact of a rotational system on the animal. Their results showed that a rotational grazing system led to a steady changing fatty acid profile in milk, because of an always changing chemical composition of grass (protein, NDF, ADF) with each rotation. Cattle are creatures of habit; a rotational grazing system represents a particular challenge for their entire metabolism.
1.5 Effects of grazing on rumen fermentation
The feed intake of the cow starts with the plucking and swallowing of big grass particle.
During rumination the cow crushes the feed particle into smaller ones preparing the feed for the fermentation in the rumen. Rumination behavior plays an important role, as it is a key component of rumen digestion (Figure 4).
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Figure 4. Graphical description of the most important relations between ration composition, nutritional level, rumen metabolism and composition of the microbial population (Own, schematic representation based on LEBZIEN (2007).
Rumination activity is influenced by the structure and amount of ingested fiber. The time for rumination increases with increasing fiber content (STEINWIDDER and WURM, 2005, ENGELHARDT von et al., 2015). The rumen is a huge fermentation chamber and comparable with a motor. The power of the motor is defined by its microbial population. The microbial population consist of different types of bacteria, protozoa and fungi. The composition of the microbes is feed dependent. They ferment and digest the plant material into the volatile fatty acids (VFA) acetate, propionate and butyrate, which are the energy substrates for the host and comparable with the engine for the motor (STEINWIDDER and WURM, 2005, ENGELHARDT von et al., 2015, STEINWIDDER and STARZ, 2015). The concentration of especially these main fatty acids defines the value of rumen pH. It can be maintained between 6 and 7, which is considered to be the optimum for cellulolytic bacteria (ABDELA, 2016). The produced VFA are absorbed by the papillae of the rumen wall. The short-chain fatty acids formed in the rumen cover up to 80% of the energy requirements of cows (STEINWIDDER and WURM, 2005). Furthermore, during rumination, saliva comes into the rumen and works as buffer, which prevents a dangerous decrease of the pH in it. An optimally functioning ruminal digestion is the basis for an optimal nutrient supply and healthy cows (STEINWIDDEr and WURM, 2005, ENGELHARDT von et al., 2015, STEINWIDDER and STARZ, 2015).
Fermentation rate
pH in the rumen Composition of
ration
Composition of
rumen microbes Rate of feed passage
Amount of dry matter intake Rumination activity
Rumen content / Stratification
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As summarized in chapter 1.4 spring grass can be rich of highly fermentable carbohydrates. A high proportion of water-soluble carbohydrates in the ration can increase the number of bacteria which especially breakdown sugars and therefore intensify the rate of rumen fermentation leading to an increase of VFA within a very short time. The organic acids accumulate in the rumen, rumen pH decreases and buffering capacity is exceeded for compensation of the accumulation of these acids (PLAIZIER et al., 2008). Therefore, the risk for a subacute ruminal acidosis increases. ZEBELI et al., 2008 defined from their results a SARA threshold of 314 min per day < pH 5.8 and a daily average pH of 6.14. A rumen acidosis leads to an increase of endotoxins (lipopolysaccharide; LPS) released by the death of gram-negative bacteria. Consequently, the digestive disorder caused by an acidosis risk can lead to dysfunction of rumen wall and therefore endotoxins can reach the blood circle and activate proinflammatory processes. This occurs mainly when high proportions of concentrate are supplied (ZEBELI and METZLER-ZEBELI, 2012) especially in combination with spring grass constituting negative influences on the general health of the animal (KLEEN et al., 2003, BRAMLEY et al., 2008, O’GRADY et al., 2008). Therefore, a ration change should always be practiced slowly. GASTEINER et al. (2015) concluded from their results observing the period during transition from confinement to pasture, that the animals need at least seven days to adapt to the new feed without health problems and further 21 to 28 days to stabilize rumen pH values.
In the experiment of SCHÄREN et al. (2016b) a decrease of rumen pH was observed after transition to fulltime pasturing, whereby the researchers supplied a small amount of concentrate (1.75 kg per cow and day, divided into two portions) during fulltime grazing. GIBBS and LAPORTE (2008) reported that already cows without concentrate supply spent about 80% of the experimental period under a pH of 6.0, 20% under 5.5 and 10% under 5.0. The combination of concentrate plus grass can increase the subacute ruminal acidosis risk extremely and this can be an issue throughout the season on pasture (MARKS, 2018). In the study of BARGO et al.
(2002) a significant decrease in the rumen pH of dairy cows on pasture supplemented with more than 8 kg of concentrate was observed.
It also needs to be stated that the proportion of the main fatty acids can vary due to feeding change. The higher WSC intake attributable to pasture increases especially the concentrations of propionate and butyrate (LEE et al., 2002, UEDA et al., 2016). Then again, VIBART et al.
(2010) observed in their study fed a TMR / partial TMR plus different proportions of pasture a
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decrease in acetate and propionate concentration. Acetate concentration was increased in the investigation of Ueda et al. (2016) which might be due to a better digestion of herbage NDF in spring. The different observations underline the influence of chemical composition of the feed and its effect on rumen fermentation pattern. The amounts of fatty acids and their proportional ratio depend on the ration and have an effect on the equilibrium of the rumen ratio.
However, rumen adaption to the new feed is inter alia dependent on VFA absorption which is influenced by rumen morphology. The studies of DIEHO et al. (2016), WANG et al. (2017) showed that diet, independent of pasture feeding, can affect the expression of genes involved in cellular growth and cell proliferation, which probably influences rumen epithelium. The assumption is that rumen papillae are stimulated to increase in size due to feed change and therefore might have a higher absorption capacity of VFA to prevent the development of SARA.
Feed change also includes alterations of the rumen content and rumen microbiota.
SCHÄREN et al. (2017) concluded that the microbiota needed two to three weeks to adapt to new circumstances (changes of the chemical composition of feed and rumen content, stratification) which is in line with the findings of GASTEINER et al. (2015).
To sum up, the adaption period of the rumen is a complex process. The time period, in which the alterations caused by the new feed takes place in the rumen might have an impact on general health of the animals.
1.6 Effects of the genetic variation on grazing
In Europe as well as in North America cows were bred in the last decades for a higher milk production per cow and year and for a short-term high input system. In New Zealand, Australia and Ireland, the low-input system is favored meaning lower milk production and minimal effort, and also preferring grass as the only feed if possible (STEINWIDDER and STARZ, 2015). Although the principles of breeding are similar across a variety of pasture-based and non-pasture systems, WASHBURN and MULLEN (2014) concluded that optimal breeds, breed strains, and selection strategies can differ based on varying management constraints and objectives. GRUBER et al. (2006) collected a lot of data regarding influencing parameters on DMI in different experimental stations in Europe. In general, they observed increasing body weight and therefore DMI to compensate high milking performance. As the milk yield potential increases, the risk of an energy deficit also rises. Cows with a higher bodyweight need
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supplemental feed to compensate this, that’s why in regions with pasture access mostly small cow breeds dominate. KOLVER et al. (2002) compared in a trial large-scale Holstein Friesian cows with small-framed Holstein Friesian cows (New Zealand type) at TMR feeding or fulltime grazing. There was a genotype-feeding interaction on the traits annual milk yield, milk content, production efficiency, BW gain during lactation and proportion of non-pregnant cows.
The small-framed New Zealand cows showed better pastureland performance than the large-framed cows - these in turn performed better on TMR feeding. (WASHBURN and MULLEN, 2014) confirmed that New Zealand Holstein Friesian are more efficient for pasture use combined with small concentrate supply. In addition, in heavier cows the heat-releasing ability ("extra heat" of the metabolism) decreases due to the relative decrease of the body surface compared to the BW. At the same time, however, higher feed intake increases the production of heat. High-performance animals thus become more sensitive to heat stress (STEINWIDDER and STARZ, 2006).
HEUBLEIN et al. (2017) observed also that different cow breeds respond differently to concentrate supplementation. Cow breeds which are adopted to concentrate supply reach higher levels of milking performance but on the other hand milking performance decreases more pronouncedly without concentrate supply. KOLVER and MULLER (1998) stated that especially large HF cows are less suited for grazing systems without concentrate supply, which was mirrored by mobilizing body reserves.
Different strains of the same breed appear to require different pasture management strategies (HORAN et al., 2005). HORAN et al. (2005) concluded that each genotype has different needs which can be managed through individual grazing systems. Higher milk yield and feed intake per animal require more intensive metabolic processes. This inevitably increases the susceptibility to metabolic disorders in suboptimal feeding conditions.
Independent of the genetic variation, DMI is limited by multifarious factors when only grass is fed. A high genetic merit meaning cows with a high-performance need balanced nutritional requirements which makes the transition from confinement to pasture a special challenge. Basically, cattle are creatures of habit. Out of this reason, vernal transition after winter feeding of TMR in confinement needs to be practiced slowly.
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1.7 Housing conditions according to welfare and behavior
Grazing cattle are a symbol of a welfare friendly system, as it allows the expression of a normal behavior which may be restricted in confinement. Legrand et al. (2009) showed that dairy cows prefer access to pasture so much as fresh feed in confinement. They concluded that the motivation of a cow to go outside was not driven by offering pasture access alone but rather by complex behavior associated processes. When given a choice for the cow to be at pasture or in confinement housing, studies have shown that time of day, season, and location when and where feed is provided can influence preference (STANZEL et al., 2018). By contrast, the results of FAJARDO et al. (2015) showed no differences for TMR or pasture choice.
However, cows on pasture spend more time for feed acquisition than cows in the stable (OSHITA et al., 2008). BARGO et al. (2002) recorded also an increasing eating time in their trial. MÜLLER et al. (2018) concluded that grazing cows experiencing a metabolic challenge try to compensate for the nutrient deficiency by increasing eating time; a behavioral element important for short‐term survival. Eating activity depends on the grazing experience of cows, too (LOPES et al., 2013). Cows without grazing experience benefit from pasture-experienced cows, resulting in a more rapid onset (COSTA et al., 2016). This underlines the challenge for animals grown up only in confinement.
Independent of the diet and housing, a large meal is always taken in the morning and in the early evening, whereas the longest meal occurs usually around sunset (GIBB et al., 1998, TAWEEL et al., 2004), which might explain the VFA fluctuations during the day (Chapter 1.6).
HILLS et al. (2015) discussed an evident effect of concentrate feeding and pasture eating time;
the general eating time decreased by 12 min for every kg DM of concentrate.
In general OSHITA et al. (2008) documented that the longer eating time relates to a smaller bite size due to more selective grazing compared to trough feeding. Cows can increase their bite rate only to a limited extent during pasture periods. Pasture is picked up in bunches, the plants are entwined by the flexible tongue and pulled into the mouth. Less feed per bite due to low coverage or pasture height comes along with a lower feed intake (STEINWIDDER and STARZ, 2015). This could imply, that a pasture system with a high grass height and coverage could have a positive effect on DMI. WOODWARD (1997) documented for example, that the time for feed acquisition rises when the coverage is less than 50%, which implements the importance of a good grazing management.
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The grazing system, moreover, requires a greater physical activity of the animals.
DOHME-MEIER et al. (2014) concluded from their results, that cows on pasture required 19%
more energy, especially for physical activity. The effect of grazing activity and energy expenditure was also investigated by KAUFMANN et al. (2011). They concluded that the energy expenditure was influenced by feeding behavior and physical activity. Grazing cows have to walk longer distances as they make more steps and spend less time lying down, compared to cows kept indoors (KAUFMANN et al., 2011).
The change to pasture also entails behavioral changes, which in turn can influence the duration of the adaption.
1.8 Effects of transition to pasture on immune-related parameters
It has been discussed in the previous chapters that transition of cows from stable to pasture is often associated with an energy deficit and a negative energy balance (NEB; calculated using the following factors: energy intake, main energy requirements, energy requirements for milk production and gestation). From many other studies it is known that a NEB as observed for early lactating cows is related to a compromised immuno-reactivity (DRONG et al., 2017).
Although the transition from late gestation to early lactation is physiologically different from the transition of a cow from confinement to pasture there are some common metabolic features.
These include mobilization of body reserves, a rise in blood levels of NEFA and BHB and an increase in liver lipid content (SCHÄFERS et al., 2017). All these factors were discussed to be related to immune responses (INGVARTSEN and MOYES, 2012, DÄNICKE et al., 2018).
The change of some of these energy related impact factors was already documented during transition to pasture in the work of SCHÄREN et al. (2016a), (2016b). Taken together, ketone bodies, and other energy related parameters can affect the immune function of leucocytes and therefore the immune competence, with consequences on the reproductive system and animal welfare in general.
Generally speaking, diet change can also lead to changes in rumen fermentation and function of the gastrointestinal tract. The gastro intestinal tract for example is involved in digestion and nutrient absorption while representing an important component of the body’s immune system and can be out of balance through diet change resulting in immune modulation (KEMIN, 2017). Maintaining gut health is essential for dairy cattle production and transition to rapidly fermentable feed can compromise gut health which can lead to changed immune cell
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activity. The studies of TREVISI et al. (2014), (2018) focus on the capability of the forestomachs to actively participate to the immune response following sterile stressors challenge; their hypothesis is that forestomachs can sense sterile and infectious stressors and react to them. The scientists focused on the infiltration of leukocytes in the rumen fluids as an important method to characterize the innate immune response with participation of mucosal-associated lymphoid tissue in cows.
From pasture we know that it is high in vitamin E concentration compared to ensiled feed.
Vitamin E is involved in many biological processes in animals, it is an antioxidant and contributes to preventing free-radical mediated tissue damage together with other defense mechanisms such as SOD and GPx (TIZARD, 2004). Especially around calving during negative energy balance and the associated immune suppression, low concentrations of vitamin E have been reported (POLITIS et al., 1995, IMMIG, 2018). Whether a negative energy balance triggered by the transition of cows from confinement to pasture also causes a drop in the vitamin E status is not well investigated.
Due to sunlight exposure the vitamin D synthesis is higher on pasture compared to indoor housing cows. Different studies have shown, that sunlight exposure increases the vitamin D concentration in milk and blood (HYMOLLER et al., 2009, GUO et al., 2018). There are two forms of vitamin D which are particularly interesting for dairy cows: vitamin D3 induced by sunlight exposure and vitamin D2 obtained by dietary intake. Comparable with the described drop down in vitamin E status (POLITIS et al., 1995, IMMIG, 2018) the same observation could be made for serum vitamin D during early lactation (HOLCOMBE et al., 2018).
Furthermore, from the review of ARNOTT et al. (2017) we know that there is a concrete tendency for a hepatic liver lipidosis for cows on pasture. The increase of liver fat content can lead to damaged liver cells but also to a liver inflammation. The liver converts vitamin D to its active form. A possible impairment of the liver function could probably also lead to a reduced process of vitamin D activation. For this reason, a drop in the vitamin D status during transition from confinement to pasture can be not excluded.
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2 Hypotheses and objectives
Full grazing pasture systems are a special challenge for the high-yielding dairy cow which is unable to meet the energy and nutrient requirement solely by pasture feed intake. Moreover, especially the transition period from confinement to pasture requires attention due to multiple physiological adaptation processes for the cow.
Based on the finding that low amounts of supplemented concentrate feed were still insufficient to counterbalance the energy deficit during transition to full-time pasture the objective of the present study was to increase the amount of concentrate feed moderately while practicing a rotational pasture system. The amount of concentrate supply during fulltime grazing was called moderate because the TMR feeding during confinement had consisted of 30% concentrate feed. With an assumed dry matter intake of 21 kg to 24 kg per cow during confinement the concentrate intake had been about 7 to 8 kg (DM) and thus higher compared to the amount of concentrate feed received during fulltime grazing.
It was hypothesized that:
• a moderate concentrate feed supply under a rotational grazing system facilitated the physiological adaptation processes to full-time grazing and alleviated energy deficiency with positive consequences for health and performance,
• transition to pasture would change the behavior of the animals compared to confinement housing cows,
• the increased intake of highly fermentable grass combined with a moderate concentrate feed supply would increase the risk for SARA with possible consequences for rumen epithelium integrity and inflammatory response.
These hypotheses were tested in a 12-week trial by comparing a confinement group fed a TMR with a pasture group gradually transitioned from TMR to full-time pasture supplemented with a moderate concentrate feed supply.
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3 Effects of a change from an indoor-based total mixed ration to a rational pasture system combined with a moderate concentrate feed supply on the health and performance of dairy cows
Authors: Julia Hartwiger 1, Melanie Schären 1,5, Ursula Gerhards 1,Liane Hüther 1, Jana Frahm 1, Dirk von Soosten 1, Jeanette Klüß 1, Martin Bachmann 2, Annette Zeyner 2, Ulrich Meyer 1, Johannes Isselstein 3, Gerhard Breves 4 and Sven Dänicke 1
1 Institute of Animal Nutrition, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Bundesallee 37, 38116 Braunschweig, Germany; Julia.Hartwiger@fli.de (JH); Melanie.Schaeren@uni-leipzig.de (MS); U.gerhards@gmx.de (UG);
Liane.Huether@fli.de (LH); Jana.Frahm@fli.de (JF); Dirk.von_Soosten@fli.de (DvS);
Jeannette.Kluess@fli.de (JK); Sven.Daenicke@fli.de (SD)
2 Institute of Agricultural and Nutritional Sciences, Martin-Luther-University Halle-Wittenberg, Theodor-Lieser-Str. 11, 06120 Halle (Saale), Germany;
Martin.Bachmann@landw.uni-halle.de (MB); Annette.Zeyner@landw.uni-halle.de (AZ)
3 Department of Crop Sciences, Grassland Science, Georg-August University, Von-Siebold-Str. 8, 37075 Göttingen, Germany; Jissels@gwdg.de (JI)
4 Institute for Physiology, University of Veterinary Medicine Hannover, Foundation, Bischofsholer Damm 15, 30173 Hannover, Germany; Gerhard.Breves@tiho-hannover.de (GB)
5 Clinic for Ruminants and Swine, Faculty of Veterinary Medicine, University of Leipzig, An den Tierkliniken 11, 04103 Leipzig, Germany; Melanie.Schaeren@uni-leipzig.de
State of publication: published online in October 2018 in Animals Journal of MDPI Contribution of authors:
• Head of organization and execution: MS, UM, SD, JI, GB
• Trial and project design: MS, JH, UM, SD, JI, MB, GB, LH, JF
• Trial implementation and sample collection: JH, MS, UG, JK, DvS
• Sample analysis: LH, JF, MB, AZ,
• Data analysis and interpretation: JH, UG, DvS, JK, SD, UM, GB
• Writing of manuscript: JH
• Revision of manuscript: SD, UM, GB, JI, LH, JF, MB Own contribution: 65 %
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4 Effects of a change from an indoor-based total mixed ration to a rotational pasture system combined with a moderate concentrate feed supply on rumen fermentation of dairy cows
Authors: Julia Hartwiger 1, Melanie Schären 1, 2, Sarah Potthoff 1, Liane Hüther 1, Susanne Kersten 1, Dirk von Soosten 1,Andreas Beineke 3, Ulrich Meyer 1, Gerhard Breves 4 and Sven Dänicke 1
1 Institute of Animal Nutrition, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Braunschweig 38116, Germany; Julia.Hartwiger@fli.de (JH);
Melanie.Schaeren@uni-leipzig.de (MS); sarah.potthoff.91@gmail.com (SP);
Liane.Huether@fli.de (LH); Susanne.Kersten@fli.de (SK); Dirk.von_Soosten@fli.de (DvS.); Ulrich.Meyer@fli.de (UM); Sven.Daenicke@fli.de (SD)
2 Clinic for Ruminants and Swine, Faculty of Veterinary Medicine, University of Leipzig, Leipzig 04103, Germany; Melanie.Schaeren@uni-leipzig.de
3 Institute of Pathology, University of Veterinary Medicine Hannover, Foundation, Hannover 30559, Germany; Andreas.Beineke@tiho-hannover.de (AB)
4 Institute of Physiology, University of Veterinary Medicine Hannover, Foundation, Bischofsholer 30173 Hannover, Germany; Gerhard.Breves@tiho-hannover.de (GB)
State of publication: published online in November 2018 in Animals Journal of MDPI Contribution of authors:
• Head of organization and execution: MS, UM, SD, GB
• Trial and project design: MS, JH, UM, SD, GB, LH
• Trial implementation and sample collection: JH, MS, SP
• Sample analysis: LH, SK, AB
• Data analysis and interpretation: JH, SP, JF, SK, MS, DvS, SD, UM, GB, AB
• Writing of manuscript: JH
• Revision of manuscript: SD, UM, GB, LH, SK Own contribution: 70 %
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5 Effects of a change from an indoor-based total mixed ration to a rotational pasture system combined with a moderate concentrate feed supply on immunological cell and blood parameters of dairy cows
Authors: Julia Hartwiger 1, Melanie Schären 1, Jana Frahm 1, Susanne Kersten 1, Liane Hüther 1, Helga Sauerwein 2, Ulrich Meyer 1, Gerhard Breves 3 and Sven Dänicke 1
1 Institute of Animal Nutrition, Friedrich-Loeffler-Institut (FLI), Federal Research Institute for Animal Health, Bundesallee 37, 38116 Braunschweig, Germany; Julia.Hartwiger@fli.de (JH), Melanie.Schaeren@uni-leipzig.de (MS), Susanne.Kersten@fli.de (SK), Jana.Frahm@fli.de (JF), Liane.Huether@fli.de (LH), Ulrich.Meyer@fli.de (UM), Sven.Daenicke@fli.de (SD)
2 Institute for Animal Science Physiology & Hygiene, University of Bonn, Katzenburgweg 7 – 9, 53115 Bonn, Germany; sauerwein@uni-bonn.de (HS)
3 Institute of Physiology, University of Veterinary Medicine Hannover, Foundation, Bischofsholer Damm 15, 30173 Hannover, Germany; Gerhard.Breves@tiho-hannover.de (GB)
State of publication: published online in May 2019 in Veterinary Sciences Journal of MDPI Contribution of authors:
• Head of organization and execution: MS, UM, SD, GB
• Trial and project design: MS, JH, UM, SD, GB, LH, JF
• Trial implementation and sample collection: JH, MS
• Sample analysis: LH, JF, SK,
• Data analysis and interpretation: JH, JF, SK, MS, SD, UM, GB
• Writing of manuscript: JH
• Revision of manuscript: SD, UM, GB, LH, JF, SK Own contribution: 75 %
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6 Discussion
6.1 General summary of the three scientific publications
The challenge for cows during transition from confinement to pasture is to maximize their herbage intake rapidly and to deal with diurnal and longitudinal changes of the chemical composition of grass. Many farmers support the limited DMI by supplementing the daily ration with concentrate feed. Various studies have shown that the amount of concentrate feed supply for grazing cows and their energy requirement depend on different aspects, e.g. physical activity, stage of lactation, milking performance, seasonal variation in pasture availability and nutritive values. Less literature can be found researching on the consequences of high fermentable grass combined with moderate concentrate feed supply on animal health during transition to pasture and in the first weeks on a fulltime grazing ration.
There are different aims of a slow transition management to pasture. Cows should be managed in order to:
• meet their energy needs, while
• gradually adjusting the rumen and the animals’ behavior to the changes of feeding and housing conditions.
It was hypothesized that the change from an indoor based TMR feeding system to a pasture-based system combined with moderate concentrate feed supply would provide sufficient energy to compensate the energy deficit triggered by an increased physical activity of cows on pasture compared to confinement; and that a daily pasture-based ration could suffice for meeting the energy requirements of mid-lactating high yielding Holstein cows.
In summary, feeding change to pasture access combined with moderate concentrate feed supply can be described as a complex physiological process (Chapter 1.1 to 1.8). Energy requirement and consumption on pasture compared to confinement housing are influenced by a range of factors. Main influencing features are the decrease in DMI, alterations in rumen variables and the higher physical activity.
A decrease in milking performance, as well as BCS and BW were the first and obvious signs of changing housing and feeding conditions. In this trial, the decrease in feed intake caused an energy lack and did consequently induce lipomobilization and short time increase of serum NEFA and BHBA concentrations (Chapter 1.2). Furthermore, a short time increase in liver fat content underlines the inability of hepatocytes to cope with an increased NEFA inflow
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from mobilized fat depots. Despite supplying a moderate concentrate feed amount combined with grass high in fast fermentable carbohydrates a decrease of rumen pH up to values indicative for SARA could be not observed. Based on the fermentation profile as recorded between 0800 a.m. and 0800 p.m., rumen total VFA concentrations showed a constant course of a two-cycle system after four weeks on a fulltime grazing ration, which was completely different to the weeks during confinement feeding or rather confinement feeding with pasture access (Chapter 1.5).
Despite some associated health risks such as an energetically unbalanced feeding, no adverse effects on blood cells or the immune response could be observed in the collected data.
The higher physical activity lead to an increase in blood hematocrit combined with an increase in red blood cell count and hemoglobin which could be interpreted as an improved oxygen supply of the PG. Furthermore, the impact of sunlight exposure and fresh green feed on pasture was mirrored in an increase of vitamin D and E concentration in blood serum. The expected drop down as described in literature during calving season and early lactation could be not observed. Actually we know, that vitamin D is a modulator of the immune response, targeting various immune cells (Chapter 1.8) which should be examined in more detail in another trial.
Further research needs to be done to describe the bioavailability of the different vitamin E compounds in dairy cows by monitoring its concentration in plasma, red blood cells and neutrophils during grazing season and its effect on neutrophil functions.
Changes of granulocytes concentration and modified cell function in case of ROS production were observed especially during the catabolic pathways of the PG, whereas other antioxidative parameters as GPx and SOD were not influenced. The balance between oxidative and antioxidative system still needs to be examined in more detail and thus the possibility of the development of oxidative stress (Chapter 1.8). The studies of TREVISI et al. (2014), (2018) et al. focused on the infiltration of leukocytes in the rumen fluids to describe innate immune responses. In our study, we investigated exclusively circulating blood lymphocytes by quantifying T-lymphocyte subsets in relation to changes of the housing system. Future trials should also investigate the methods of TREVISI et al. (2014), (2018) to characterize the innate immune response with participation of mucosal-associated lymphoid tissue in cows.
The DMI decreased during transition to pasture and stayed low during fulltime pasturing compared to confinement feeding at the beginning of the trial. The grazing system which had
