630 EAAP – 67th Annual Meeting, Belfast 2016 Application of a milk MIR methane prediction equation to Swiss dairy cattle population data
F. Grandl1, A. Vanlierde2, M.-L. Vanrobays3, C. Grelet2, F. Dehareng2, N. Gengler3, H. Soyeurt3, M. Kreuzer4, A. Schwarm4, A. Münger5, F. Dohme-Meier5 and B. Gredler1
1Qualitas AG, Chamerstr. 56, 6300 Zug, Switzerland, 2Walloon Agricultural Research Centre, Valorization of Agricultural Products Department, Chée de Namur, 24, 5030 Gembloux, Belgium, 3University of Liège, Gembloux Agro-Bio Tech, Passage des Déportés, 2, 5030 Gembloux, Belgium, 4ETH Zürich, Institute of Agricultural Sciences, Universitätstr. 2, 8092 Zürich, Switzerland, 5Agroscope, Institute for Livestock Sciences ILS, Tioleyre 4, 1725 Posieux, Switzerland; florian.grandl@qualitasag.ch
To make use of genetic variation of methane (CH4) emissions in dairy cattle, a large number of individual CH4 emissions across entire populations are needed. As direct measurement of animal CH4 production is very laborious, alternatives like the prediction of CH4 emissions are needed. A promising approach for this purpose is the use of milk mid-infrared (MIR) spectral data, which is readily available from routine milk recording analyses. A published MIR prediction equation was applied to spectral data from routine milk recording in Switzerland from August to October 2015. Swiss spectral data has been standardised to reduce spectral variability between instruments. In total, 933,307 spectral data were available from the time period.
In a first step only data from Swiss Holstein cows in their 1st to 4th lactation and with less than 306 days in milk were considered in the study, which resulted in 88,974 predicted daily CH4 production values from 40,082 cows. Semiparametric regression analysis using regression splines was carried out using the R package mgcv. Without any correction for diet, animal, and management influences, increasing CH4 production from lactation 1 to 4 was found and changing emissions during lactation were identified. Combining the predicted CH4 emissions with additional herd book data allows a more detailed population-wide screening for potentially high or low emitting animals. The information can be used for management purposes and genetic analyses.
In a joint project, the analyses will be extended to other breeds and adding new reference measurements will increase accuracy and robustness of the prediction equation.
The cow for the system: limiting milk yield and body condition loss to ensure reproduction on time N. Bedere1, L. Delaby1, S. Leurent-Colette2 and C. Disenhaus1
1INRA, AGROCAMPUS OUEST, PEGASE, Saint-Gilles, 35590, France, 2INRA, Domaine Experimental du Pin- au-Haras, Exmes, 61310, France; nicolas.bedere@rennes.inra.fr
To study reproductive performances of Holstein and Normande cows managed under a compact calving system (3 months), 2 contrasted grazing-based feeding systems (FS) are used since 2006 in a trial at the INRA farm of Le Pin-au-Haras. The High FS enables cows to produce more milk (MY) while limiting their body condition loss whereas the Low FS limits MY while inducing a large body condition loss throughout lactation (High vs Low: +2,355 kg MY for Holstein, +1,402 kg MY for Normande and +0.40 body condition score in both breeds, P<0.001). It was possible to study the different steps of the reproductive process by combining milk progesterone information (sampled 3 times a week) with intensive oestrous behaviour recording and pregnancy diagnosis (using ultrasonography). Cyclicity of dairy cows was not affected by FS. Normande cows had an earlier resumption of ovarian activity (28.0 vs 31.5 d) and a higher proportion of normal cyclicity patterns than Holstein cows (+22 points, P<0.001). Estruses were more intense in the Low FS than in the High one (+13 points standing to be mounted, P<0.001). For Holstein cows, fertility problems were different in each FS: in the Low FS a higher proportion of inseminations were not-fertilizing or resulted in early embryo mortality (+14 points, P<0.05) whereas in the High FS a higher proportion of inseminations resulted in late embryo mortality (+9 points, P<0.05). Finally, Normande had a higher re-calving rate than Holstein (+19 points, P<0.001), and the High FS tended to be positively associated with re-calving rate (+6 points, P<0.10).
The Low FS was very restrictive in nutrients. By limiting their MY to this nutritive constraint Normande do not experience too severe negative energy balance while Holstein tried to maintain the highest MY possible.
This resulted in preserved reproduction for Normande cows, and thus animals more robust to compact calving and grazing-based dairy systems.
