Undernutrition pre- and post-mating affects serum levels of glucose, cholesterol and progesterone, but not the reproductive efficiency of crossbred hair ewes synchronized for estrus

The aim of this study was to determine the effects of nutritional restriction pre- and post-mating on serum concentrations of some metabolites and progesterone after the conception, as well as on the reproductive performance of crossbred hair ewes subjected to a synchronization of estrus (progesterone plus 200 IU of PMSG) and natural mating during the reproductive season. At d 30 before mating, 48 Katahdin x Pelibuey multiparous ewes (Body weight [BW] = 50.3 ± 0.5 kg, body condition score [BCS] = 3.0 ± 0.06 units) were assigned, under a randomized complete block design, to one of four dietary treatments (n = 12): 1) control (no nutritional restriction [NR]), 2) NR pre-mating (30 d, NRPRE), 3) NR post-mating (50 d, NRPOS) and 4) NR in both periods (80 d, TNR). All ewes were fed the same diet but NR ewes were fed only 60% of the nourishment offered to control. Compared to the other treatments, BW and BCS at mating were higher (P < 0.01) in control and NRPOS ewes, but at 50 d post-mating were higher (P < 0.01) in control and NRPRE ewes. At lambing, TNR ewes had the lowest (P = 0.03) BW and BCS, while serum concentrations of triglyceride, total protein and urea were unaffected (P ≥ 0.13) by the treatments. Also, lower glucose (P = 0.03) and higher (P = 0.02) cholesterol in serum were observed in NRPOS ewes than ewes of the other treatments. Progesterone concentrations were similar (P ≥ 0.39) among treatments until d 8 post-mating, and then (d 10-20) were higher (P ≤ 0.05) in NRPOS and TNR ewes than in NRPRE ewes. Estrus behavior, pregnancy, abortion rate, gestation length, fertility, fecundity and prolificacy were unaffected (P ≥ 0.40) by treatments. In conclusion, NR around mating alters serum concentrations of glucose, cholesterol and progesterone in the early gestation, but not the reproductive efficiency of crossbred hair ewes synchronized with progesterone and PMSG. Results indicate the high ability of crossbred hair ewes to prioritize their reproductive capacity under malnutrition scenarios during the breeding season.