Abstract

GUZMAN MARTINEZ, Vanessa; CASTILLO LINARES, Erika Belem; HINOJOSA CUELLAR, José Alfonso  and  OLIVA HERNANDEZ, Jorge. Body weight of the yearling ewe at first breeding program and productivity in its first two lambing. Nova scientia [online]. 2022, vol.14, n.28, 00003.  Epub Aug 01, 2022. ISSN 2007-0705.  https://doi.org/10.21640/ns.v14i28.2960.

The body weight of the ewes indirectly reflects their size and body composition. Its knowledge at the beginning of a reproductive and productive process can be of great value in determining the future productivity of the ewes. The aim of this study was to determine the effect of the body weight and the zoometric measurements of Blackbelly x Pelibuey yearling ewes at the beginning of mating on their productive and reproductive efficiency in their first two productive cycles. The productive and reproductive records of 26 ewes fed based on grazing and food supplementation were used. The study factor was the body weight category of yearling ewes (light, 20.3 kg; 59 % of body weight multiparous ewes; n = 13 and medium 24.3 kg; 70 % of body weight multiparous ewes; n = 13). The response variables were: body weight, daily weight gain, number of lambs and litter weight (at birth and weaning); reproductive parameters related to conception, gestation duration and lambing and total kilograms of lamb at weaning and gross income (MEX $) from the sale of total kilograms of lamb at weaning in the first two production cycles. The body weight category of ewes affected the change in body weight and daily weight gain during breeding (P < 0.05), as well as the weight of the litter at weaning during the first lactation and the intervals between mating and first estrus, mating, and conception, first lambing at conception, and between the first and second lambing (P < 0.05). During the second production cycle, the productive efficiency of the ewes was not affected by the body weight category (P > 0.05). The body weight category with which the ewes start their first breeding affected the reproductive and productive efficiency during the first breeding and first productive cycle. The productive efficiency of the ewes was not affected by the body weight category during the second production cycle. Higher body weight and body size in ewes allowed fewer days to manifest estrus and achieve conception in the first breeding; likewise, it favored the production of litters at weaning with greater weight in the first lactation, but not in the second. However, the total kilograms of lamb at weaning during the first two production cycles was higher in medium ewes compared to light ewes.

Keywords : litter; productive efficiency; growth; lactation; hair sheep; postpartum; reproduction; humid tropic; productive cycle; sheep; Pelibuey; Blackbelly; conception; gestation; mutton; weaning; estrus; production.

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