Effects of long-acting melatonin implants on the reproductive performance of Corriedale, Borderdale, Romney, Coopworth, and Perendale ewes in New Zealand
| Autor: | T. C. Reid, P. D. Muir, T. W. Knight, G. H. Scales, L. D. Staple, Smith Jf, S. R. McPhee |
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| Rok vydání: | 1992 |
| Předmět: | |
| Zdroj: | New Zealand Journal of Agricultural Research. 35:185-193 |
| ISSN: | 1175-8775 0028-8233 |
| DOI: | 10.1080/00288233.1992.10417717 |
| Popis: | Two experiments compared the effect of long-acting melatonin implants (Regulin®) on the reproductive performance of commercial sheep flocks joined in late spring or early summer. A third experiment used melatonin implants in an attempt to induce an early January mating in Romney ewes. In Experiment 1, Corriedale and Borderdale ewes in five flocks in the South Island had joining dates from 17 December to 11 January 1988. In Experiment 2, Romney, Coopworth, Perendale, and their crosses in 11 flocks in the North Island had joining dates from 12 January to 4 March 1989. Up to half of the ewes in each flock had melatonin implants inserted 20–34 days before joining. Ultrasound scanning at 50–60 days was used to determine the number of foetuses present. There were decreases in barrenness (1–49%) and increases in ewes with multiple foetuses (4–35%) in all the South Island flocks and the eight North Island flocks joined during mid January. The mean net effect was an additional 30.8 and 23.0 foetuses/100 e... |
| Databáze: | OpenAIRE |
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