Bioscientifica Proceedings

Summary. European breeds of rams appear to be responsive to photoperiodic changes even though there are large differences between breeds in the timing and amplitude of endocrine (LH and testosterone) and gametogenetic variations before the sexual season. Light regimens such as 6-month light cycles or alternations of constant short and long days every 12–16 weeks are able to entrain the parameters of sexual activity. In these regimens in which the period ...

Summary. In the ram, changes in daylength influence testicular activity by modifying the release of luteinizing hormone-releasing hormone (LH-RH) and thus the gonadotrophins. To investigate the nature of this response the hourly fluctuations in the circulating levels of prolactin, luteinizing hormone (LH) and melatonin were measured in rams kept under various artificial lighting conditions.In Exp. 1, 8 Soay rams (4 control and 4 from whi...

Studies of low birth weight offspring have a long history in pig science. These pigs have reduced growth potential and poor carcass quality compared to their higher birth weight littermates. In contemporary commercial sows with between 10 and 15 total pigs born/litter, between-litter differences in average birth weight appear to make the largest contribution to variation in postnatal growth performance, independent of numbers born. Low birth weight is a characteristic of...

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