Milk Production and Constituents of Beef Cows with Different Breed Compositions

Abstract

Background: There are two classes of factors that affect cow milk production and, as a consequence, the performance of calves: environmental and genetic factors. Considering the importance of milk production of beef cattle, it is essential to measure the milk production of such cows. However, such estimation presents some difficulties, especially when cows are raised exclusively in a grazing regime. This study aimed to evaluate the milk production and the nutritional composition of beef cows from eight different breed compositions (Angus: ANAN, Hereford: HHHH, Nellore: NENE, Hereford-Angus: HHAN, Angus-Hereford: ANHH, Nellore-Angus: NEAN, Angus-Nellore: ANNE, and Caracu-Angus: CRAN) raised under continuous natural pasture grazing, besides evaluating the calves' adjusted weight at 210 days until weaning.Results: NEAN cows were the most productive but did not differ from ANNE, ANHH, and CRAN, with estimated average yields of 6.2, 5.97, 5.93 and 5.86 kg/day, respectively, throughout the lactation period. NENE cows presented the lowest yields, with a daily average of 4.61 kg, although this value did not differ significantly from those of HHHH, ANAN and HHAN cows, which had means of 4.67, 4.79 and 4.84 kg/day, respectively. Calves of CRAN, NEAN, and ANNE cows were heavier than calves of ANAN, HHAN, HHHH, and NENE cows at weaning, not differing from ANHH cows, which in turn also had heavier calves than HHHH cows. NEAN, ANNE, HHHH and NENE cows had higher concentrations of total solids in milk than ANAN and ANHH.Conclusions: In conclusion, as expected, the crossbreeding of genetically more distant breed increases the milk production of beef cows. Therefore, for cow-calf operations in a subtropical climate, crossbreeding between Angus and Nellore or Caracu can be used as a genetic tool to increase cow maternal ability, through greater milk production and nutrient content, and consequently yielding heavier calves at weaning.