Proceedings
A project developed as part of the management procedure of Laurelwood Acres Dairy was conducted to induce spring and summer breeding. Yearling springborn does and mature bucks of all five common dairy breeds were exposed to 20 hours of continuous light daily (4 a.m. to 12 a.m.) for approximately 70 days during winter and spring. The bucks were placed with the does approximately six weeks after the end of the light treatment. Control animals consisted of spring-born does that were exposed to the bucks the following fall. The results of two years have been calculated. In 1978 135 does were light-treated from 26 January through 5 April. Estrual activity was first observed 25 May. Fifty-nine percent of the light-treated does kidded from 30 October to 15 December, 1978. The average number of kids per treated doe kidding was 1.2. Fifty control does were included in 1978 and 68 percent of these kidded the following spring. The average number of kids per control doe kidding was 1.5. In 1980, 119 does were light-treated from 2 February through 5 April. Estrual-activity began 22 May. Seventy-two percent of does kidded from 8 October to 21 December, 1980. The average number of kids per treated doe kidding was 1.4. As in the previous year, 68 percent of control does kidded the following spring. The average number of kids per control doe kidding was 1.4. Although no untreated does were exposed to bucks with those that were light-treated, concurrent research and experience have shown that kidding by untreated does exposed to bucks during spring and early summer rarely exceeds 5 percent. This work suggests that the light treatment given can cause conception rates during spring and summer comparable to those of untreated does during the regular fall breeding season
Main Authors: | , , , , , , |
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Format: | biblioteca |
Published: |
Scottsdale, AZ (EUA)
1982
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Subjects: | CAPRINOS, REPRODUCCION, ESTACIONALIDAD, EPOCA DE EMPADRE, FOTOPERIODISMO, ESTADOS UNIDOS DE AMERICA, |
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