Association between milk urea nitrogen and first service conception in smallholder dairy farms under heat and humidity stress

Abstract

Aim:The study was to evaluate the relationship between the first service conception (FSC) and milk urea nitrogen (MUN) in smallholder dairy farms under heat and humidity stress.Materials and Methods:Dairy cows from 43 dairy farms giving birth between November 2014 and April 2015 (n=295) contributed to the study. All cows were sampled monthly to measure milk compositions, and we collected additional farm data from farmers through a questionnaire. The first service during the first 120 days of lactation was the outcome of interest in this study. Multivariable logistic regression determined significant associations with FSC.Results:The overall FSC was 22% and the mean MUN concentration was 11.55 mg/dl. The final FSC model included MUN concentration, the season of breeding, and protein energy ratio (PE ratio) in the diet. The odds of FSC were reduced by approximately 10% for each mg/dl higher MUN on the day of the milk sample that was nearest to the artificial insemination (AI) day. The odds of FSC were nearly 3 times higher when the first insemination occurred in winter compared to summer first services. Taking into account the nutritional factors, the odds of FSC were nearly 70% higher with an increase in PE ratio of 10 g of crude protein/Mcal from the mean of 35.90 g.Conclusion:This study of smallholder dairy farmers in the hot and humid climate of Thailand confirmed that season, nutritional management, and MUN concentration were associated with FSC. MUN appears to be a useful indicator to monitor the effects of diet on reproductive performance from this study.

Effect of Heat Stress on Subsequent Estrous Cycles Induced by PGF2α in Cross-Bred Holstein Dairy Cows Raised in Ratchaburi Province, Thailand

“…Furthermore, HS reduces the potential for oocyte development [40]. Therefore, HS led to a lower FSCR [41,42] and a prolonged average CTFS [23]. Therefore, it might also directly affect the extension of open days (calving-to-conception interval) [24].…”

Variación del nitrógeno ureico en leche según la temporada del año y días en leche

“…El NUL es un indicador importante y efectivo para establecer el estatus de nitrógeno ureico en vacas lecheras, pues esta herramienta permite identificar fácilmente una subalimentación o sobrealimentación de proteína (11,12). Su monitoreo es importante porque el NUL está relacionado con desórdenes de tipo reproductivo, e incremento de células somáticas, así como con un aumento en la excreción de nitrógeno con un impacto ambiental negativo (10,13,14,15). En Colombia, pocos estudios se relacionan con el análisis de NUL en rebaños lecheros (16,17), y con la variación del NUL con respecto a los días en leche (DEL) en las condiciones de clima tropical del país.…”