Animal Molecular Breeding, 2024, Vol.14, No.6, 370-379 http://animalscipublisher.com/index.php/amb 372 Table 1 Frequencies and means ± standard error for estrus responses, ovulations (%), total number of corpuses luteum (n), ovulation rate (units), luteal tissue volume (mm3), type of ovulation (%), and pregnancy rate (d36, %) from multiparous crossbred/rangeland goats (n = 38) (i.e., extensive system) receiving (SG, n = 19) or not (NSG, n = 19) a nutritional supplementation of feed leftovers from a dairy cow enterprise (i.e., intensive system) in Northern Mexico 1 (Adopted from Machado-Ramos et al., 2023) Variables Groups SG NSG Estrus induction (%) 16/19 (84.21) 13/19 (68.42) Latency to estrus (h) 99.75±8.7 101.54 ± 12.3 Estrus duration (h) 32.25±3.2 31.38±4.0 Goats ovulating, n(%) 15/19 (78.94) a 9/19 (47.36) b Total number of corpora luteum, (n) 27a 14b Ovulation rate (n) 1.42±0.23a 0.73±0.21b Luteal tissue volume (mm3) 657±100 424±89 Type of ovulation: -Single, n(%) 4/15 (26.67) 4/9 (44.44) -Double, n (%) 9/15 (60.00) a 4/9 (44.44) b -Triple, n(%) 2/15 (13.33) 1/9 (11.11) -Multiple, n(%) 11/15 (73.33) a 5/9 (55.55) b Pregnancy rate, d36, n (%) 13/19 (68.42) a 7/19 (36.84) b Note: 1 The SG was supplemented from day −5 to +15 in relation to the mating period; d0 = onset of the experimental out-of-season breeding (i.e., 28 March to 7 April). SG = supplemented group; NS = non-supplemented group. a,b Response variables with different superscript between columns within row differ (p≤ 0.05) (Adopted from Machado-Ramos et al., 2023) Table 2 Conception rate (%), kidding rate (%), litter size (LSM±SE), and birth weight (LSM±SE) of Abergele goats synchronized with the PMSG and PGF2α protocols (Adopted from Wondim et al., 2022) Protocol N Mating (%) Conception (%) Kidding (%) Litter size (LSM±SE) Birth weight (LSM±SE) Treatments *** * PMSG 24 15 (62.5) 9 (37.5) 6 (66.6) 1.5 ± 0.20 1.8 ± 0.04 PGF2α 44 44 (100) 29 (65.9) 25 (86.2) 1.0 ± 0.03 2.1 ± 0.04 Overall 81.25 51.7 76.4 1.1 ± 0.05 2.0 ± 0.03 CV 24 10 Note: Here, PMSG = pregnant mare serum gonadotropin hormone, PGF2α = prostaglandin f2α, N = total population, LSM = least square means, and SE = standard error, * = p< 0.05, *** = p< 0.001 (Adopted from Wondim et al., 2022) 3.2 Nutritional management for reproductive health Nutritional management plays a crucial role in enhancing reproductive health and performance in goats. Supplementation with energy-rich feeds, such as maize, has been shown to increase the number of follicles, follicle growth rate, and ovulation rate in anestrous goats (Nogueira et al., 2016). Nutritional supplements can also elevate plasma concentrations of metabolic hormones like insulin, leptin, and IGF-1, which are associated with improved follicular development and reduced rates of follicular atresia. Proper nutritional management ensures that goats maintain optimal body condition, which is essential for successful breeding and high fertility rates. 3.3 Genetic selection for seasonal breeding adaptability Genetic selection is a powerful tool for improving seasonal breeding adaptability in goats. By selecting for traits such as litter size, ovulation rate, and breeding season length, breeders can enhance the reproductive efficiency of their herds (Ehrhardt et al., 2019). Crossbreeding with divergent breeds can rapidly reset genetic potentials for these traits, followed by within-breed selection to optimize reproductive performance (Notter, 2012). Although heritabilities for reproductive traits are generally low, strategic genetic selection can lead to significant improvements in seasonal breeding adaptability.
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