Productive Performance of Sheep in an Agropastoral System on the Coast of Oaxaca, Mexico

Abstract

Objective: To determine the prolificacy and weight of lambs at birth (BW) in twogenotypes of hair sheep within an agropastoral system on the coast of Oaxaca, Mexico,and to evaluate the effect of two sources of selenium on the performance of lambs fromsaid system during the fattening phase.Design/Methodology/Approach: The study was carried out in an agropastoral system(coconut palm and Cynodon dactylon grass) in Río Grande, Oaxaca. Two experimentswere conducted; the first studied 58 ewes distributed in a completely randomized design(CRD) with factorial arrangement of 2x2x3, and focused on the following fixed effects:genotype, number of births, and body condition (BC). The measured variables wereprolificacy and BW. The second experiment studied 23 lambs of 4 months in age thatwere offspring of the females in experiment 1. They were distributed in a CRD withthree treatments: T1, without selenium provided; T2, with barium selenate provided; T3,with selenomethionine provided. The dependent variables were daily weight gain(DWG), dry material consumption (DMC), and feed conversion (FC). Results: The Pelibuey ewes with one and two births and the Black Belly ewes with onebirth demonstrated the highest averages in prolificacy (P?0.05). The lowest averages(P?0.05) were detected in ewes with BC 4 irrespective of number of births. The BW wasaffected (P?0.05) by genotype; Black Belly lambs weighed 680 g (P?0.05) more thatPelibuey lambs. The DWG, DMC and FC behaved similarly (P?0.05) betweentreatments and their general averages were 0.114 kg day -1 , 0.679 kg day -1 , and 6.18,respectively.Study Limitations/Implications: In the agropastoral system, the BC of ewes limitstheir reproductive performance. The weight of the lambs at the start of fatteningdetermines their performance during fattening.Findings/Conclusions: In the agropastoral system, Pelibuey and Black Belly femalespresent adequate prolificacy averages and BW; however, it is very important that theyremain within BC 3. Neither of the two sources of selenium improves DWG, DMC, andFC of lambs fattened in pens in the agropastoral system.