Periódicos Brasileiros em Medicina Veterinária e Zootecnia

p. 01-04

Efeito da duração do intervalo de partos e estação do ano ao parto sobre a eficiência reprodutiva subsequente de vacas leiteiras mestiças

Lucia Bonato, GabrielaMaria dos Santos, Ricarda

Background: The need for high production has increased considerably in the dairy industry. On the other hand, a fertility decline has been observed in cows with best potential for milk production. Therefore, calving intervals of around 12 months have been sought, which leaves a very short period of time for the cows to be inseminated and to become pregnant. If the conception is delayed, the reproduction inefficiency can reduce milk production, causing economic problems. The calving-conception interval (CCI) depends on multiple factors such as voluntary waiting period, insemination technique, birth season, herd size and parity. Negative effects of stress caused by heat on the fertility of lactating dairy cows have been observed. An increase in body temperature decreased the probability of conception at 28 days as the number of postpartum days increased. It is known that cows with larger calving-conception intervals have more health problems. Also, they have a greater chance of being discarded, since long CCI result in longer periods with no milk production and, therefore, expenditures with unproductive cows. Moreover, an increase in the CCI from 90 to 300 days doubled the chance of discard or peripartum death in dairy matrix. This study aimed to analyze the effect of two variables: the calving - first IA interval and on the CCI of crossbred dairy cows: duration of previous calvi

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