The body condition score and live weight influence on predicted nitrogen excretion with urine
2015
Petrovska, S., Latvia Univ. of Agriculture, Jelgava (Latvia) | Jonkus, D., Latvia Univ. of Agriculture, Jelgava (Latvia)
The purpose of research was to analyze dairy cows (Bos taurus) milk productivity according to the calving body condition score (BCS) and to predict the nitrogen output with urine according to BCS and live weight. The research was carried out at the Research and Study farm ‘Vecauce’ of Latvia University of Agriculture. Data were collected from 55 dairy cows during October 2013 to October 2014. Dairy cows were from different breeds (Holstein Black and White, red breed cows with Holstein blood more than 40% and crossbreeds) and different lactations. Cows were grouped in two groups for the estimation of BCS effect on the analyzed traits: BCS is less than or equal to 2.5 and BCS is greater than or equal to 2.6. BCS was estimated at calving and in monthly recording control days. Nadir value of BCS is greater than or equal to 2.6 group was 2.64 ± 0.06 points on the third control day, but 2.46 ± 0.08 points of BCS is less than or equal to 2.5 on the second control day. Calving live weight of BCS is less than or equal to 2.5 and BCS is greater than or equal to 2.6 groups were 613.8 ± 13.3 kg and 651.1 ± 11.4 kg. The highest milk yield was observed in BCS is greater than or equal to 2.6 group until the third control day, the highest fat content was observed in this group, but the highest protein content was in BCS is less than or equal to 2.5 group. Milk urea content was not significantly affected by calving BCS, but milk urea content of BCS is greater than or equal to 2.5 group ranged from 23.2 ± 1.86 to 30.9 ± 1.98 mg dLE-1, and from 20.6 ± 1.53 to 30.2 ± 2.27 mg dLE-1 in BCS is greater than or equal to 2.6 group. A significantly higher urinary nitrogen output was observed from BCS is greater than or equal to 2.6 group on the second control day – 237.8 ± 8.1 g dayE-1 (p is less than 0.05).
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