Milk production of suckler cows: a study of the main variation factors

Abstract

Measuring suckler cow Milk Production (MP) consists in the evaluation of the milk drunk by the calf during two repeated weighings before and after suckling. This measurement is difficult to implement and limited to experimental centers. A database was created grouping the milk drunk measured over 15 years by charolais, limousin and salers cattle from the HERBIPÔLE (more than 12,000 measurements, more than 1 000 cows checked at least 7 times per cow and per lactation) in order to update our quantitative knowledge of the production of suckler cows and study the major variation factors. Breed is a major factor of production: 1 600 ± 313 kg milk / lactation in limousin, 1 840 ± 355 kg in Charolais and 2 250 ± 470 kg in Salers and a difference of approximately 11% can be observed between primiparous and multiparous - i.e. 1kg/d. In a “classic” system of “broutard” production with calvings in the winter and semi-extensive pastures, two production peaks are observed. The first peak occurs one month after calving and the second larger peak just after access to pasture. This peak varies from 0.8 to 2.3 kg depending on the breed, parturition and calving period. A focus was made on the factors affecting the peak around access to pasture. The study enabled the quantification of the persistence of lactation and its variability (- 17 to - 27 g milk drunk /d). Persistence is best for low-producing cows (- 0.5 against - 0.9 kg less milk /d over one month). Better MP leads to a better weight gain of the calves. Throughout lactation, the average weight gain is 60 g/liter of extra milk drunk, i.e. a gain in live weight of 70 kg for a lactation of 2 300 kg compared to a lactation of 1 200 kg. Selection of production of the mother and lactation persistence therefore reduces food purchased for weanlings. This supports the need to measure the MP more systematically and throughout lactation. The milk production of a cow suckling her calf is not very sensitive to reductions in energetic or global supplements if the reduction is less than 3 UFL, in fact this function takes priority regardless of the state of weight gain during calving. Nevertheless, the MP can be reduced significantly in the event of a longer period of even moderate under-nourishment. In winter calvings, the quality of grass ingested in the spring largely covers (110%) the high nutritional requirements of lactation. This allows the cow to re-establish lactation and to reconstitute the reserves mobilized during the winter period, and thus the breeder can economize on the feed distributed.