Reproductive characterization of hair sheep in the American tropics: a review
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Keywords
Puberty, estrous, estrous cycle, ovulation rate
Abstract
Objective: to make a reproductive characterization of the hair sheep breeds in the American tropics.
Design/methodology/approach: reproductive variables information was collected from scientific search engines, such as Web of Science, Redalyc, Dialnet, PubMed, SciELO and Latindex.
Results: the age of puberty in ewe lambs is highly variable. Similar results were found in adult ewes regarding estrus duration and incidence, estrous cycle length, seasonal anestrus, ovulation rate, fertility, gestation, and prolificacy.
Limitations on study/implications: information on reproductive variables of hair sheep breeds is poorly known or non-existent.
Findings/conclusions: puberty onset in ewe lambs ranges from 175 to 335 d of age when animals weight 15 to 43 kg. The length of the estrous cycle of hair sheep in Mexico is 17 d during the autumn-winter and 21 d in spring-summer. In Brazil, it lasts 17 d in spring-summer and 18 d in autumn-winter. In the United States of America and Venezuela, the estrous cycle length was similar in both periods of the year. The estrous occurrence was 97.1% in autumn-winter and 76.5 % in spring-summer. The estrous duration ranges from 16 to 52 hours. Seasonal anestrous occurs from May to July. The ovulation rate ranges from 1 to 3 oocytes. Fertility is 80 to 100 % in temperate and 37 % in warm months. Gestation length ranges from 144 to 152 d. Prolificacy ranges from 1.0 to 2.2 offspring per ewe. The lambing interval range from 244 to 294 d.