CH-1725 Posieux www.alp.admin.ch michel.rerat@alp.admin.ch
Influence of the age of entry in the fattening unit on the growth performance and health status
of veal calves
M. Rérat
Introduction
Figure 1: Mean concentrations of IgG in serum of the calves during the first 7 weeks after arrival. Differences between the groups in the same week with different characters are significant (P< 0.05). Group effect: P< 0.05; time effect: P< 0.001; group × time effect: P<
0.001.
The decline of IgG concentrations after arrival in group A2-4and A5-7 and its increase after 3 weeks (Figure 1) could be explained by the decline of maternal antibodies and the begin of endogenous production of antibodies.
The stable IgG concentrations of older calves (group A8-10) can be explained by the full dominance of the active immunity system.
Blood Traits
Mean overall concentration of IgG in group A2-4(7.26 ± 0.45 g/L) was significantly (P< 0.05) lower than those of group A5-7(8.52
± 0.43 g/L) and A8-10(8.88 ± 0.42 g/L).
The lower IgG concentrations in group A2-4could be explained by the immune deficiency of the calves during the period of change from a passive to an active immunity. But an important factor that could influence significantly IgG values is the distribution of a certain quantity and quality of colostrum after birth.
However these differences were not reflected by any differences in health status as shown by the equal number of treatments per group.
The mixing of animals from different farms and the confinement procedures of the transport from the farm to the fattening unit often cause respiratory diseases during the first weeks after arrival in the fattening unit. As it coincides with a period of change from a passive to an active immunity the health of the animals could be more severely affected.
The main objective of this study was to determine the effect of different ages of veal calves at the arrival in the fattening unit on their growth performance and health status.
Material and Methods
Three groups of calves arriving with different ages (group A2-4, A5-7, and A8-10: arrival at an age between 2 and 4, between 5 and 7, and between 8 and 10 weeks; n = 27, 29, and 30, respectively) were submitted to similar experimental conditions.
The calves were weighed weekly.
The health status of every calf was evaluated on day of arrival in the fattening unit and weekly during the whole experiment. In addition to the weekly clinical examinations, the health status of the supposed sick calves only was evaluated. The common experimental period for health data to all calves of the three groups was between the week of arrival and the ninth week after arrival.
Blood samples were taken on day of arrival, on week 1, 3, 5, and 7 after arrival and the determination of immunoglobulin G (IgG) was made using a kit (Bovine IgG ELISA quantitation kit).
Results and Discussion
Growth Performance
During a common period for growth data (weeks 10 to 18 of life) mean average daily gain (ADG) of group A2-4(1.53 ± 0.04 kg/d) was significantly (P< 0.001) higher than A5-7(1.26 ± 0.03 kg/d) and A8-10(1.21 ± 0.03 kg/d).
These results could be explained by a shorter period with different feeding conditions between birth and the begin of the trial for the calves of the group A2-4.
Health Status
At least 50% of the medical treatments for respiratory disorders in group A5-7 (50 ± 6.9%) and A8-10 (54 ± 6.9%) were done during the first two weeks after arrival and this level was significantly lower (P < 0.05) in group A2-4 (28.6 ± 7%).
In spite of less sick calves in group A2-4 during the first two weeks, the sum of antibiotic treatments per group during the experimental period was the same.
Based on the absence of correlations in the three groups between IgG concentrations at arrival and ADG or number of antibiotic treatments, it can be concluded that the lower concentrations of IgG in group A2-4were not reflected by any differences in health status and that the age of arrival in the fattening unit in this trial had no influence on the growth performance or health status of the veal calves.
weeks after arrival
arrival 1 3 5 7
IgG, g/L
4 6 8 10 12 14
Group A2-4 Group A5-7 Group A8-10
a ab
a b
a a
a
a a b
a a
a b b
