Research Article

Changes in the body condition and daily milk yield of cows during lactation depending on the level of fat reserves before calving

Danuta Borkowska, Ewa Januś, Robert Polski

¹ University of Life Sciences in Lublin, Faculty of Bioeconomy in Zamość, Poland

² University of Life Sciences in Lublin, Faculty of Animal Biology and Breeding, Poland

1. Acta Sci. Pol. Zootechnica, 14(1), 2015, 41‒50

Abstract. The aim of the study was to analyse the effect of the level of fat reserves accumulated in the bodies of cows before parturition on changes in their body condition and daily yield after calving. The study was carried out in five herds of Polish Black-and-White Holstein-Friesian cows and included 242 cows in which 4.890 body condition scores were determined before calving and during 435 lactations and dry periods. In addition, 4.430 test-day milking results were analysed. Statistical calculations were performed in SAS software (GML procedure). The statistical model took into account the effect of body condition before parturition, the farm, and the lactation number and stage of lactation after calving on the rate of changes in daily milk yield in kg FPCM and on body condition score (BCS) during lactation. We found that in cows that accumulated insufficient fat reserves before parturition, daily yield did not increase at the beginning of lactation. Moreover, body condition scores did not decrease in these cows. The highest daily yield at the beginning of lactation, and subsequently the highest rate of its decline, were noted in the cows whose BCS before calving was at least 3.5. A score of 3.5 before calving was found to be the most beneficial for productivity up to the 6th month of lactation, as well as for the release of energy from fat tissue after calving and subsequent replenishment of reserves.

Keywords: body condition of cows, daily milk yield, course of lactation, changes in body condition