Nutrition, pathology, reproduction and productivity of the dairy cow

Abstract

The objective of this study was to determine the effect of disease on milk production and their relationships with milking characteristics and milking career. This work was carried out at the same time as a feed trial (comparison of feed based on hay or silage with two different amounts of concentrate) which lasted 6 years and concerned 487 lactations of 190 "Pie-Noire" and "Montbéliarde" cows. During the 487 lactations, 595 health problems were observed, which concerned 59 % of these lactations, at an average rate of 2.1 per lactation. Lameness and mastitis represented 52 and 24 %, respectively, of all infections. 47 % of mastitis occured during the first two months of lactation, whereas the frequency of lameness increased throughout winter to reach a maximum when the animals were turned out to pasture. In the short term (5 weeks), the greatest loss in production was caused by winter mastitis (24 kg) and particularly lameness arising from animals being turned out to pasture (56 kg). Throughout the milk producing period it is repeated bouts of lameness which cause the greatest loss in milk production  : 640 kg of milk for cows having had 3 lamenesses or more as opposed to 20 kg for those having had only one lameness and 160 kg for those with one or several mastitis infections. Repeated lameness was 3 times greater in "Pie-Noire" cows than in "Montbéliardes" and 4 times more frequent in cows having received winter feed based on silage than those receiving hay based feed. Four main classes of milk production can be distinguished based on the amount of milk produced, animal health, their reproduction and finally, their culling. The differences in milk production between the 4 groups reached 1 800 kg of milk per lactation. Cows receiving grass silage feed with a small amount of concentrate had a shorter milking career than those on other types of feed (2.5 as compared to 3.2 - 3.5 lactations). Cows with serious health problems (multiple lameness) in their first lactation had a much shorter milking career (1.1 lactation) than cows that were healthy in their first lactation. On average, milk production and live weight increased, respectively, 622 and 51 kg, between the first and the third lactation. This increase in milk production was greater in cows receiving winter fodder based on hay (high or low amount of concentrate) or based on grass silage with a high amount of concentrate (+ 752 kg) than those being fed on rations of grass silage with a low amount of concentrate (+ 359 kg). Over 3 lactations, the greatest difference in milk production between the groups (hay + high amount of concentrate, silage + low amount of concentrate) reached 2 770 kg thus a difference of 26 %. These findings demonstrate that certain conclusions based on results obtained during winter or from lactation must be reconsidered.

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