Reproductive characterization of hair ewe in the American tropics: a review part 1

Resumen

Objective: To carry out a reproductive characterization of the breeds of hair ewe in the tropical region of the Americas.

Design/Methodology/Approach: A search of scientific information about the reproductive variables of breeds of hair ewe was carried out and the results were analyzed in the Web of Science, Redalyc, Dialnet, PubMed, SciELO, and Latindex databases.

Results: We described and discussed the highly-variable onset of puberty in ewe lambs. Similar results were found in adult ewes regarding the duration and occurrence of the estrous, estrous cycle length, seasonal anestrous, ovulation rate, fertility, gestation, and prolificacy.

Study Limitations/Implications: Information about the reproductive variables of breeds of hair ewe is poorly known or non-existent.

Findings/Conclusions: The onset of puberty in 15-43 kg ewe lambs ranges from 175 to 335 d of age. The estrous cycle of hair ewe in Mexico lasts 17 d in autumn-winter and 21 d in spring-summer. In Brazil, this cycle 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 occurrence of the estrous reached 97.1 % in autumn-winter and 76.5 % in spring-summer. The duration of the estrous ranges from 16 to 52 hours. Seasonal anestrous occurs from May to July. The ovulation rate ranges from 1 to 3 oocytes. The percentage of fertility fluctuates between 80 and 100 % in temperate months and reaches 37 % in warm ones. Gestation lasts from 144 to 152 d. Prolificacy ranges from 1.0 to 2.2 offspring per ewe. The lambing interval ranges from 244 to 294 d.