Effect of nutrition pre-breeding and during pregnancy on breeding performance of ewe lambs
2010
Mulvaney, F.J. | Morris, S.T. | Kenyon, P.R. | Morel, P.C.H. | West, D.M.
The objective of the present studies was to investigate the effect of differing nutritional levels before breeding and during the pregnancy period on the breeding activity, conception rate (proportion pregnant/ewe lambs bred), pregnancy rate (proportion pregnant/ewe lambs joined with the ram) and the number of fetuses identified at pregnancy diagnosis. In Study 1, ewe lambs were allocated to either 'medium' or 'ad lib' levels of herbage from 4 days before the start of the breeding period (P -4) to P64. In Study 2, four different pre-breeding nutritional groups ('maintenance', 'medium', 'medium/ad lib' and 'ad lib') were utilised from P -17 until P5. The 'medium/ad lib' group involved a nutritional switch from the 'medium' to the 'ad lib' group at P -4 and remained in the 'ad lib' until P5. At P5, all ewe lambs that were identified as bred (crayon-marked by ram) were allocated to either 'medium' or 'ad lib' levels of nutrition until P122. In Study 1, more (P 0.05). In addition, more (P 0.05) the proportion of ewe lambs displaying oestrus post-breeding, pregnancy rate or the number of fetuses identified at pregnancy diagnosis per ewe lamb present. This indicates that New Zealand pastoral farmers should aim to allow ad libitum levels of nutrition immediately before the start of the breeding period to pregnancy diagnosis to maximise the number of fetuses at pregnancy diagnosis.
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