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Evaluation of influence of milk urea nitrogen on reproductive performance in smallholder dairy farms
Author(s) -
Kananub S,
Pechkerd P,
VanLeeuwen J,
Stryhn H,
Arunvipas P
Publication year - 2020
Publication title -
australian veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.382
H-Index - 59
eISSN - 1751-0813
pISSN - 0005-0423
DOI - 10.1111/avj.12946
Subject(s) - zoology , ice calving , lactose , lactation , insemination , biology , artificial insemination , pregnancy , food science , genetics
Objective The aim of this study was to determine the relationship between milk urea nitrogen (MUN) and reproductive performance in dairy cows in western Thailand. Design All cows calving from November 2014 to April 2015 were included in the study, a total of 486 cows from 47 farms. Each cow had milk constituents and MUN tested monthly up to confirmed conception or until the 8th month after parturition. Each farm had a dietary assessment completed. Cox proportional hazard models with shared frailty were used to determine associations of conception rate. Results Cows became pregnant increasingly quickly over time, except during 100–150 days of lactation. A change in MUN from 12.5 to 13.5 mg/dL on the closet day to breeding was associated with a 5% decrease in conception. Milk protein was negatively associated with hazard of conception, whereas milk lactose and dietary protein:energy ratio had positive associations with conception rate. Breeding season was also significant; the highest conception rate was observed in cows inseminated during winter, whereas insemination during the humid rainy season resulted in the lowest conception rates. The farm random effect in the model was strongly significant. Conclusion Detrimental effects of higher MUN on rate of conception were identified. The rate of conception was positively associated with protein:energy ratio in the study. Therefore, good nutritional management leading to positive energy balance should benefit conception rates.