The effect of body condition at weaning and its subsequent evolution on the resumption of oestrus activity of Rasa Aragonesa ewes
1995
Dapoza, C. | Zarazaga, L. | Castrillo, C. | Forcada, F. (Universidad de Zaragoza, Zaragoza (Spain). Facultad de Veterinaria, Dept. de Produccion Animal y Ciencia de los Alimentos)
The effect of body condition at weaning and its subsequent variation on the resumption of oestrus activity was studied in thirty-seven Rasa Aragonesa ewes lambing in the anoestrus season (May 7th-14th). The ewes were kept in individual cages during the experiment period and were distributed in two groups according to their body condition score (BCS greater than or equal to 2.5 and less than or equal to 2.25). Ewes were given ad libitum 3 per cent ammonia treated barley straw, supplemented with either 500 or 250 g/d of concentrate. Digestible organic matter intake (DOMI) was higher in ewes receiving 500 g/d of concentrate and in those with a lower BCS at weaning. Changes in body energy, estimated from the dilution space of deuterium oxide, were better correlated (r = 0.70) to DOMI than the changes in live weight (r = 0.22) and BCS (r = 0.51). Neither did body condition score of the ewes nor the level of concentrate in the diet significantly affect the date of commencement of oestrus activity. The percentage of ewes with oestrus activity after progestative treatment, measured by laparoscopy, was greater in ewes with BCS greater than or equal to 2.5 at weaning than in those with BCS less than or equal to 2.25 (P less than or equal to 0.01). Increasing level of supplementation from 250 to 500 g/d promoted higher ovulation rates in ewes with low body condition (P less than or equal to 0.05).
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