Influence of nutritional and socio-sexual cues upon reproductive efficiency of goats exposed to the male effect under extensive conditions

Abstract

This study evaluated the effect of nutritional supplementation and socio-sexual cues upon reproductive efficiency of goats exposed to the male effect under rangeland grazing conditions (22°N). Criollo goats (n = 73) were distributed in four experimental groups: (1) continuous males (CM, n = 19) in which males (n = 2) remained together with females from 7 March to 28 July; (2) supplemented males (SM, n = 16) in which males (n = 2) were kept separately and were individually supplemented with 18% crude protein and 2.77 Mcal ME kg–1 DM, during a 30-day period; (3) supplemented males exposed to the female effect (SM + FE, n = 19), in which supplemented males (n = 2) were maintained with females induced to oestrus before being used for male effect; and (4) supplemented males and supplemented females (SM + SF, n = 19) in which males (n = 2) were supplemented as in group SM, and females received the same supplementation as males 30 days before and 30 days after male introduction. Grazing was performed from 0900 to 1900 hours; liveweight (LW) was registered weekly before grazing and (or) supplementation. Ovarian activity was evaluated (serum P4 concentrations) in the four groups before and after male introduction. At the beginning of the study and supplementation, female LW did not differ among treatments (P > 0.01). However, during the supplementation phase, LW increased in a different fashion among groups (P < 0.002), favouring the SM, SM + FE and SM + SF groups. A positive correlation between female LW at the beginning of the rainy season and the onset of ovulatory activity was observed (r = +0.90; P < 0.01). The average date for the onset of ovarian activity differed (P < 0.001) among groups, being earlier in the SM + SF group (9 May ± 4.3 days), which also depicted the shortest interval between the introduction of males until the onset of ovulatory activity (P < 0.001). Results of the present study indicate that nutritional signalling of the reproductive activity of both female and male Criollo goats reared under marginal conditions surmounts the inhibitory effects of long-day photoperiods during the non-reproductive season. An increased level of nutrition during the anestrous season may be used to increase reproductive function of both male and female goats reared in harsh nutritional conditions and applied as a green, clean, and ethical reproductive tool at these latitudes.

Physicochemical characterization of goat milk produced in the Comarca Lagunera, Mexico

“…The consumption of grasses, herbaceous, and shrub species, without the consumption of concentrates (grains), explains the higher content of FT found in S2. Other studies have found evidence that the seasonal and environmental changes in food availability promote changes in the reproductive annual pattern (Flores‐Najera et al., ; Meza‐Herrera & Tena‐Sempere, ) and in turn in the quality and quantity of goat milk (Paz, Togo, Usandivaras, Castel, & Mena, ). Also, a reduction in the consumption of concentrates (sorghum) by lactating goats and substitution with orange peel, results in higher milk fat (Hernández‐Meléndez et al., ).…”

The use of melatonin and progestagen–eCG to initiate reproductive activity in prepuberal Awassi ewe lambs

“…The reason behind that may be related to body weight, metabolic status, and age. Certainly, both body weight and metabolic status are a crucial signaling cues activating GnRH neurons and promoting the interaction among the hypothalamic-hypophyseal-gonadal components, resulting in the establishment of reproductive function (Flores-Najera et al 2010;Guerra-García et al 2009;Meza-Herrera et al 2010a, b;Urrutia-Morales et al 2009). Kridli et al (2006a) have shown that Awassi ewe lambs reach puberty at around 280 days of age when they reach 36 kg of body weight.…”

Sistemas De Producción De Oveja Awassi Y Rendimiento Reproductivo: Una Experiencia Del Medio Oriente

“…La heredabilidad de la mayoría de las características económicas es muy baja. Los factores ambientales más importantes que afectan el desempeño reproductivo son: (1) el balance de energía y nutrición, (2) el fotoperiodo y la temporada, (3) los factores socio-sexuales, (4) la temperatura, la humedad, y (5) el estrés (Scaramuzzi y Martin, 2008;Urrutia-Morales et al, 2009;Flores-Najera et al, 2010;González-Bulnes et al, 2010;Meza-Herrera et al, 2010;2011). La reducción de energía disponible o la mala condición corporal afecta el estro y la ovulación impidiendo la liberación hipotalámica de la hormona luteinizante (LH) a partir de la glándula pituitaria anterior.…”

“…The heritability of most economic traits is quite low. The major environmental factors affecting reproductive performance include: (1) nutrition and energy balance, (2) photoperiod and seasonality, (3) socio-sexual factors, (4) temperature and humidity, and (5) stress (Scaramuzzi and Martin, 2008;Urrutia-Morales et al, 2009;Flores-Najera et al, 2010;González-Bulnes et al, 2010;2011). Reduced available energy or poor body condition negatively affect estrus and ovulation inhibiting the hypothalamic release of luteinizing hormone (LH) from the anterior pituitary gland.…”