Factors affecting reproductive function in beef cows during lactation | Factores que afectan a la función reproductiva en vacas nodrizas durante la lactación
2009
Álvarez Rodríguez, J., Centro de Investigación y Tecnología Agroalimentaria de Aragón, Zaragoza (España) | Casasús, I., Centro de Investigación y Tecnología Agroalimentaria de Aragón, Zaragoza (España) | Sanz, A., Centro de Investigación y Tecnología Agroalimentaria de Aragón, Zaragoza (España)
This study analysed factors affecting productive and reproductive function of beef cows (n=148) from Parda de Montaña (PA) and Pirenaica (PI) breeds calving in the autumn (AU) or winter (WI) and nursing once- (1S), twice-daily (2S) or ad libitum (AS). Weight was recorded weekly. Twice-weekly blood samples were collected to analyse progesterone and cow activity was monitored through collars. Calving weight was lower in PA than in PI, it was greater in AU than in WI. Also, calving weight was greater after cows reached 6 years, and it was lower in cows that later resumed ovulation with a short cycle. Weight gains were only affected by suckling system, being higher in 1S and 2S than in AS. Interval to first ovulation (IFO) was lower in cows between 4.1-6 and >/= 10 years. The latter was lower in AU than in WI. 1S and 2S had lower IFO than AS, but there was no breed effect. Only 65.3% of the cows were detected in oestrus. The interval to first oestrus (IFE) was not affected by season, suckling system or breed, but it was greater in cows having 6.1-10 years. Cows calving with body condition score </= 2.5 had longer IFE than >2.5.
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