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The potential effect of intravenous administration of glutamate on the ovarian activity and the LH secretion pattern, considering the anestrous yearling goat as an animal model, were assessed. In late April, yearling goats (n = 20) were randomly assigned to either (1) Glutamate supplemented (GLUT; n = 10, Live Weight (LW) = 29.6 ± 1.02 kg, Body Condition (BCS) = 3.4 ± 0.2 units; i.v. supplemented with 7 mg GLUT kg−1 LW) or (2) Non-supplemented (CONT; n = 10; LW = 29.2 ± 1.07 kg, BCS = 3.5 ± 0.2 units; i.v. saline). The oats were estrus-synchronized; blood sampling (6 h × 15 min) was carried out for LH quantification. Response variables included pulsatility (PULSE), time to first pulse (TTFP), amplitude (AMPL), nadir (NAD), and area under the curve (AUC) of LH. Ovaries were ultra-sonographically scanned to assess ovulation rate (OR), number of antral follicles (AF), and total ovarian activity (TOA = OR + AF). LH-PULSE was quantified with the Munro algorithm; significant treatment x time interactions were evaluated across time. The variables LW and BCS did not differ (p > 0.05) between the experimental groups. Nevertheless, OR (1.77 vs. 0.87 ± 0.20 units), TOA (4.11 vs. 1.87 ± 0.47 units) and LH-PULSE (5.0 vs. 2.2 pulses 6 h-1) favored (p < 0.05) to the GLUT group. Our results reveal that targeted glutamate supplementation, the main central nervous system neurotransmitter, arose as an interesting strategy to enhance the hypothalamic−hypophyseal−ovarian response considering the anestrous-yearling goat as an animal model, with thought-provoking while promising translational applications.

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The last third of gestation is a period of high energy and protein demand for the dam to support fetal growth and the following onset of lactation. Methionine is an essential amino acid that contributes to protein formation, fetal development, and milk synthesis; thus, is likely to have positive effects on the weight and size of the newborn and, afterward, milk yield and milk composition, which may improve growth patterns of the progeny. To test these hypotheses, we used 60 pregnant multiparous Alpine goats with similar live weights and gestational ages (~Day 100 of pregnancy; Mean ± SD; 1410 ± 14 days old and 50.4 ± 6.6 kg) and were separated into two groups: control and supplemented with the delivery. Treatments were T-MET (n = 30; received 1% herbal methionine Optimethione® dry matter based on from Day 100 of the pregnancy to delivery) or T-CTL (n = 30; served as the control and did not receive methionine). The methionine powder provided individual supplementation and was adjusted every week as the live weight and dry matter intake changed. At birth, the weight, body mass index (BMI), birth type, and sex of the kids were determined. Subsequently, the progeny was weighed weekly up to weaning. Two weeks after parturition, the milk composition was recorded weekly, and the milk yield was recorded monthly. The maternal live weight at the start (Mean ± SEM; T-CTL: 50.5 ± 1.1 vs. T-MET: 50.3 ± 1.3 kg) and end (T-CTL: 54.2 ± 1.3 vs. T-MET: 52.8 ± 1.4 kg) of the experiment did not differ statistically among treatments (p > 0.05); however, daily live weight changes tended to differ between groups (T-CTL: 73 ± 10 vs. T-MET: 51 ± 7 g day−1; p = 0.06). The birth weight (T-CTL: 3.1 ± 0.1 vs. T-MET: 3.5 ± 0.1 kg; p < 0.001), daily live weight change (T-CTL: 121 ± 6 vs. T-MET: 141 ± 6 g day−1; p < 0.01), and weaning weight (T-CTL: 8.3 ± 0.2 vs. T-MET: 9.3 ± 0.3 kg; p < 0.01) differed between treatments. The BMI at birth (T-CTL: 0.28 ± 0.01 vs. T-MET: 0.3 ± 0.01 units kg m−2; p < 0.01) and at weaning (T-CTL: 0.85 ± 0.1 kg vs. T-MET: 1.00 ± 0.06 units kg m−2; p < 0.05) differed between treatments. Milk components (protein, fat, lactose, and solids non-fat) and milk yield were similar between treatments (p > 0.05). It is concluded that the inclusion of methionine in the maternal goat diet during the last third of gestation increases the birth and growth variables of the progeny but without significant influence on the milk yield and composition.

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The traditional goat production systems on arid and semi-arid rangelands of northern Mexico are characterized by minimum external inputs; therefore, little is known about goat response to technological improvements. This observational study aimed to ascertain the effect of using improved goat production technologies and breed on milk yield and reproductive performance of goats on rangeland. The study was conducted from January 2017 to June 2018. Thirty-seven goat herds comprising 6393 animals were used. Goats supplemented with 250 g of concentrate (S-goats; 14% crude protein) 30 days before breeding produced significantly more daily milk yield (218 ± 61 vs. 200 ± 60 g) than the unsupplemented (UNS-goats) goats. Milk production per lactation was 12 percentage points greater in goats with access to plain salt throughout the year than those without salt access. The absence of deworming significantly depressed daily milk yield (189 ± 55 vs. 221 ± 61 for non-treated and treated goats). In 5 months, the lowest total milk yield was for Boer goats (26.9 ± 8.3 kg) and the highest for Nubian goats (36.1 ± 9.2 kg). The kidding rate was significantly higher in the S-goats than in the UNS-goats group (66.9 vs. 62.8%). Salt-supplemented goats had a significantly greater kidding rate than goats not receiving salt (68.5 vs. 61.2%). The lowest kidding rate was for Saanen goats and the highest for Nubian goats (66.2%). These findings indicate that milk yield and reproductive performance were primarily influenced by supplementing grazing goats with concentrates and salt in this semi-arid rangeland.

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Tillandsia recurvata is an epiphyte that grows on the canopy of many trees in tropical and subtropical areas of America. The objective of this study was to evaluate the effect of partial or complete substitution of sorghum stubble with T. recurvata on liveweight change, metabolic profile, and complete blood count of goats fed increasing levels (0, 30, and 60%, dry matter basis) of T. recurvata. Thirty non-pregnant three-year-old, non-lactating, healthy mixed-breed goats, ten animals per treatment (T0, T30, and T60), were adapted to diets and facilities for 14 days (d-14). Blood samples were collected at d-15, 28, and 56. At the last phase of the trial (from days 67 on), control goats tended to gain more (p = 0.09) weight than their counterparts consuming T. recurvata. Plasma protein, glucose, triglycerides, calcium, and phosphorus concentrations did not differ among dietary treatments (p > 0.05). Dietary treatment influenced red blood cells (higher for T60; p < 0.01), white blood cells (higher for T30; p < 0.05), mean corpuscular volume (higher for T0; p < 0.001), and mean corpuscular hemoglobin concentration (higher for T0; p < 0.01), although not the rest of the blood variables (p > 0.05). The hematocrit percentage tended to be higher (p = 0.06) in T30 than T0 and T60. It was concluded that replacing sorghum stubble with T. recurvata did not modify the metabolic status and maintained live weight of goats. Nevertheless, the use of T. recurvata as feed for goats would improve the nutrition of these animals in the dry season compared to the current diet obtained from an arid rangeland, reducing production costs, and would alleviate the damage caused by this aggressive epiphyte to host trees.

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We tested whether the milk yield capacity of mixed-breed goats on a Chihuahuan desert rangeland in northern Mexico during the dry season affects milk composition, body weight gain, and weaning weight of their progeny. Milk yield and composition, and progeny postnatal growth performance, were recorded weekly. One week after kidding, mixed-breed goats (a mixture of Criollo × dairy breeds; n = 40) were allotted into medium (MP) or low (LP) milk yielding groups (20 goats per group). Mean 105-d total milk yield for MP and LP goats was 45.2 ± 12.5 and 20.7 ± 5.2 L, respectively. Milk lactose (4.3 vs. 4.2%) and solids-non-fat (SNF; 8.2 vs. 8.0) differed (p < 0.05) between MP and LP goats; milk protein content tended to differ (p = 0.08) between MP and LP goats with no difference for milk fat content (p > 0.05). Maternal body weight was positively associated with milk yield, milk lactose, and SNF content (p < 0.05 to p < 0.001). Goats giving birth to males produce more milk than goats giving birth to females, but milk fat percentage was higher in goats bearing females (p < 0.001). Milk yield and composition throughout lactation did not influence body weight gain (47.8 vs. 48.7 g/day for kids from MP and LP goats) and weaning weight (6.7 vs. 6.7 kg from MP and LP goats) of the offspring (p > 0.05). Birth weight and weaning weight of the progeny were positively related to maternal body weight (p ≤ 0.05). The postnatal growth of the kids was reduced, extending the time to reach market weight. Nevertheless, non-supplemented mixed-breed goats reared on semi-arid rangeland of northern Mexico have the potential for moderate milk production. Therefore, due to the limited nutrients ingested by grazing goats during the dry season, a nutritional supplement is necessary to keep up milk production and adequate growth of kids.

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We tested whether periconceptional nutrition with cladodes from the cactus, Opuntia ficus-indica, with or without protein-enrichment, improved the metabolomic profile and reproductive outcomes of adult female sheep. Sixty Rambouillet ewes of similar body weight were randomly allocated among three nutritional treatments that were fed during the breeding period (34 days): Control (Control; n = 20), Opuntia (Opuntia; n = 20) and protein-enriched Opuntia (E-Opuntia; n = 20). There were no effects of treatment on body weight but assessment of urine samples indicated that, for 76 metabolites, the Control and Opuntia groups differed completely (P < 0.05), whereas there was overlap between the Control and E-Opuntia groups. It appears that, in Opuntia-fed and Control-fed sheep, different functional groups are activated leading to changes in the metabolism of glucose, tyrosine, methane, and glycerolipids. Fertility and reproductive rate tended to be higher in the Opuntia (70% and 95%) and E-Opuntia (90% and 110%) groups than in the Control (55% and 65%), and an orthogonal contrast revealed the difference between Control and Opuntia to be significant for both reproductive variables (P < 0.05). We conclude that nutritional supplementation with Opuntia cladodes, with or without protein enrichment, increased fertility rate and reproductive rate of female sheep, without any accompanying increases in body weight. Our observations suggest that the reproductive responses to Opuntia do not simply reflect a response to good nutrition, but might be caused by specific metabolites/metabolomic pathways, perhaps by an activation of the metabolism of glucose, methane, tyrosine and glycerolipids. There are few reports relating these metabolomic compounds with the metabolism of the sheep, let alone with reproductive efficiency. The novelty of these discoveries suggests that we need further research into the mechanisms through which nutrition affects the reproductive system.

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We tested whether maternal energy supplementation during the last third of gestation improves birth weight, neonatal wellbeing, and mother-young bonding. Thirty-six pregnant French Alpine goats were randomly allocated among three nutritional treatments for the last third of pregnancy: (i) Control, fed alfalfa (T-0; n = 12); (ii) alfalfa + 150 g/head daily energy concentrate (T-150; n = 12); (iii) alfalfa + 300 g/head daily energy concentrate (T-300; n = 12). At birth, we collected progeny data on birth weight, birth type, sex, rectal temperature, heart rate, respiratory rate, time to standing, time to udder connection, and time to first feeding. For the dams, we collected data on the duration of labor, time to clean the progeny, and time to allow first suckling. At birth, body weight, rectal temperature, heart rate, and the respiratory rate did not differ among treatments (p > 0.05). In the dams, labor duration was not affected by the treatments (p > 0.05). The T-150 dams were faster to clean the newborn and allow first suckling (p < 0.05). The T-150 progeny were faster to stand and the T-300 progeny were faster to connect to the udder (p < 0.05). We conclude that energy supplementation of the dam during the last third of gestation does not affect the birth weight of the progeny, but enhances the mother-young bonding.

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The present study tested whether feeding ewes during the last third of pregnancy with cladodes of Opuntia (untreated or protein-enriched), as an alternative to alfalfa hay, would improve milk yield as well as the pre- and post-natal growth of their lambs. Sixty mature Rambouillet ewes and their progeny were randomly allocated among three nutritional treatments: (i) Control, fed alfalfa; (ii) Opuntia, fed untreated cladodes; (iii) E-Opuntia, fed protein-enriched cladodes (pre-treated with urea and ammonium sulphate). Birth weight did not differ among treatments (p > 0.05) but Control ewes produced more milk than both groups of Opuntia-fed ewes (p < 0.05). However, milk yield was not related to the growth of the progeny (p > 0.05) because lambs from E-Opuntia-fed ewes grew faster (p < 0.01) and were heavier at weaning (p < 0.05) than lambs from the other two groups. We conclude that Opuntia (with or without protein enrichment) can be used as an alternative to alfalfa hay for feeding ewes during the last third of pregnancy and therefore reduce production costs under extensive conditions in arid and semiarid regions. Moreover, protein-enriched Opuntia appears to improve postnatal lamb growth.

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The possible out-of-season effect of beta-carotene supplementation on ovulation rate (OR), antral follicles (AFN), and total ovarian activity (TOA = OR + AFN) as related to the LH release pattern in yearling anestrous goats was evaluated. In late April, Alpine-Saanen-Nubian x Criollo goats (n = 22, 26 N) were randomly allotted to: (1) Beta-carotene (BETA; n = 10, orally supplemented with 50 mg/goat/d; 36.4 ± 1.07 kg live weight (LW), 3.5 ± 0.20 units, body condition score (BCS) or (2) Non-supplemented (CONT; n = 12, 35.2 ± 1.07 kg LW, 3.4 ± 0.2 units BCS). Upon estrus synchronization, an intensive blood sampling (6 h × 15 min) was accomplished in May for LH quantifications; response variables included (pulsatility-PULSE, time to first pulse-TTFP, amplitude-AMPL, nadir-NAD and area under the curve-AUC). Thereafter, an ultrasonography scanning was completed to assess OR and AFN. The Munro algorithm was used to quantify LH pulsatility; if significant effects of time, treatment or interaction were identified, data were compared across time. Neither LW nor BCS (p > 0.05) or even the LH (p > 0.05); PULSE (4.1 ± 0.9 pulses/6 h), NAD (0.47 ± 0.13 ng) and AUC (51.7 ± 18.6 units) differed between treatments. Nonetheless, OR (1.57 vs. 0.87 ± 0.18 units) and TOA (3.44 vs. 1.87 ± 0.45 units) escorted by a reduced TTFP (33 vs. 126 ± 31.9 min) and an increased AMPL (0.55 vs. 0.24 ± 0.9 ng), favored to the BETA supplemented group (p < 0.05), possibly through a GnRH-LH enhanced pathway and(or) a direct effect at ovarian level. Results are relevant to speed-up the out-of-season reproductive outcomes in goats while may embrace translational applications.

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The aim of the present study was to develop and evaluate an equation to predict body weight (BW) using hip width (HW) in Pelibuey ewe lambs and ewes. Five hundred seventy-seven 2-month-old to 3-year-old, non-pregnant, non-lactating, clinically healthy ewe lambs and adult ewes with a mean BW of 34.7 ± 12.4 kg and HW of 15.6 ± 3.4 cm were considered. Three equations were evaluated: BW (kg): - 19.17 + 3.46 × HW (Eq. 1), BW (kg): - 17.79 + 3.25 × HW + 0.007 × HW2 (Eq. 2) and BW (kg): 0.39 × HW1.63 (Eq. 3). Independent data from 80 animals with similar characteristics (BW of 23.4 ± 10.9 kg and HW of 12 ± 3.1 cm) were also considered to evaluate the developed equations. The evaluation was based on the relationship between the observed and predicted values of BW analysed using a linear regression, the mean squared error of prediction (MSEP), the root MSEP (RMSEP) and the concordance correlation coefficients (CCCs). Additionally, cross-validation analyses were performed using the k-folds validation (k = 10) procedure. The correlation coefficient (r) between BW and HW was 0.94 (P < 0.001). The parameters for precision and accuracy showed that the proposed equations had high precision (R2 > 0.95%), accuracy (Cb > 0.98) and reproducibility (CCC > 0.96) in predicting the BW of ewe lambs and adult ewes. Equation (1) accurately predicted observed BW, with a bias (observed - predicted) of 4.3 kg and RMSEP of 9.68% with respect to the observed BW (random error of 84.23%); it also generated the best prediction according to the residual mean squared prediction error, coefficient of determination and mean absolute error. In conclusion, the highly correlated relationship between BW and HW in Pelibuey ewe lambs and adult ewes under humid tropic conditions enabled the development of mathematical models herein to estimate BW with an adequate goodness of fit. The linear model showed the best performance according to the goodness-of-fit evaluation and internal and external validation; hence, this model is proposed for use in both the experimental and commercial farms.

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The possible effect of glutamate supplementation upon ovarian reactivation and serum concentrations of insulin (INS) and triiodothyronine (T3) in anestrous yearling goats was evaluated. Goats (n = 32, 12 mo., 26° North, 1117 m) with a similar live weight (LW) and body condition score (BCS) were blood sampled twice per week for two weeks (2 × 1 week × 2 weeks) to confirm the anestrus status (<1 ng P4/mL; RIA). Thereafter, goats were randomly assigned to either 1) Glutamate (GLUT; n = 16, LW = 27.1 ± 1.09 kg, 3.5 ± 0.18 units, IV-supplemented with 7 mg of glutamate kg-1 LW), or 2) Control (CONT; n = 16; LW = 29.2 ± 1.09 kg; BCS = 3.5 ± 0.18, IV saline). During the treatment period, 16 goats (eight/group) were blood sampled twice per week for six weeks. Such serum samples (2 × 1 week × 6 weeks) were quantified by their P4 content to evaluate the ovarian-luteal activity, whereas a sample subset (1 × 1 week × 6 weeks) was used to quantify their INS & T3 content to evaluate their metabolic status. Neither LW (28.19 kg; p > 0.05) nor BCS (3.51 units; p > 0.05) differed between treatments. Goats depicting ovarian reactivation favored the GLUT group (50 vs. 12.5%; p < 0.05). Neither INS (1.72 ± 0.15 ng mL-1) nor T3 (2.32 ± 0.11 ng mL-1) differed between treatments, yet a treatment x time interaction regarding INS & T3 concentration across time favored (p < 0.05) the GLUT group. The results unveil exogenous glutamate as an interesting modulator not only of ovarian reactivation, but of metabolic hormone synthesis.

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Two experiments (Australia and Mexico) tested whether feed intake (FI) and wool production (WP) are affected by pregnancy (PRG), litter size (LZ), or lamb sex (LS) in Merino-type ewes. In Experiment-1, ewes were either not pregnant (NPR; n = 6), or carrying 1 (PR1; n = 7) or 3 (PR3; n = 11) fetuses, were studied in individual pens. NPR ewes had lower (p < 0.02) FI throughout PRG and lactation (LAC), except around lambing (p < 0.001). Following lambing, FI increased in PRG ewes (p < 0.001) to double the values in NPR ewes. PRG reduced WP (p < 0.001); in PR3, WP was lower than for both PR1 and NPR (p < 0.001). WP decreased during LAC and was lower in ewes rearing lambs than in NPR ewes (p < 0.001). Experiment-2 used 48 pregnant ewes (28 bearing singles and 20 bearing twins). Dam and lamb live weights (LW) and body condition (BC) were recorded from birth to weaning at 60 d, and dam fleece weight (DFW) was measured at weaning (12 months growth). WP was higher in ewes bearing and rearing single lambs than in ewes bearing twins (p < 0.001). DFW was positively (p < 0.01) related to LZ, dam LW, and BC, but not to changes in dam LW during LAC, or to lamb weight at birth or weaning, or LW gain, or LS. In conclusion, FI was affected during PRG and by LZ during LAC, whereas WP was influenced by LZ, but not LS, only during pregnancy.

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ABSTRACT Objective. The present study consisted in characterizing the dual-purpose cattle system and the factors that limit the productivity of this system in northern Sinaloa, Mexico. Material and Methods. We applied a survey to 214 producers and we analyzed the data with analyses of factors and conglomerate. Results. The analysis of factors identified five components: resources level, productivity, technological level, livestock management and socioeconomic aspects and these components explain 70.5% of the total cumulative variance. The conglomerate analysis identified three clusters: cluster 1 (52.5%, 105 producers) defined as a system focused on milk production. Cluster 2 (41.5%, 83 producers) defined as traditional farms of meat and milk production and Cluster 3 (6%; 12 producers) defined as farms focused on meat production. The three clusters present similar livestock management (p>0.05). The producers base their feeding strategies on grazing rangeland with seasonal supplementation of silage and commercial concentrate; however, each cluster differed (p<0.05) in the level of use of these resources. Conclusion. The present study identifies, in the dual-purpose cattle system in northern Sinaloa, low milk yield and limit forage resources as main problems that results in multiple strategies that the producers follow to solve it. The social aspects and the level of resources (land, animals, machinery and equipment and infrastructure) play an important role therefore they must be considered independently to help to define differentiated technological strategies.

RESUMEN Objetivo. El estudio consistió en realizar una caracterización del sistema bovinos de doble propósito y los factores que limitan la productividad de este sistema en el norte de Sinaloa, México. Materiales y Métodos. Se aplicó una encuesta a 214 productores y la información se analizó mediante un análisis de factores y de conglomerados. Resultados. El análisis de factores identificó cinco componentes; nivel de recursos, productividad, nivel tecnológico, manejo del ganado y aspectos socioeconómicos. Estos cinco factores explican el 70.5% del total de la varianza acumulada. El análisis de conglomerados identificó tres clústers o grupos: Clúster 1 (105 productores, 52.5%) se definió como sistema enfocado a la producción de leche, Clúster 2 (83 productores, 41.5%) definido como explotaciones tradicionales productoras de carne y leche y Clúster 3 (12 productores, 6%) definido como explotaciones enfocadas la producción de carne. Los tres clústers presentan un manejo similar del ganado (p>0.05). Los productores de los clústers basan sus estrategias de alimentación del ganado en el pastoreo con suplementación estacional de ensilaje y concentrado comercial, no obstante, cada clúster tiene diferentes (p<0.05) niveles de uso de recursos. Conclusiones. El presente estudio identifico, en los sistemas bovino de doble propósito del norte de Sinaloa, como problemas principales una baja producción de leche y escasez de forraje que se manifiesta en múltiples estrategias que siguen los productores para resolverla. Los aspectos sociales y el nivel de recursos (tierra, animales, maquinaria, equipo e infraestructura) juegan un papel importante por lo que deben de ser considerados de manera independiente para la definición de estrategias tecnológicas diferenciadas.

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The possible influence of the "male effect" upon reproductive outcomes of adult anestrous goats under marginal rangeland conditions and supplemented with protein-enriched Opuntia megacantha Salm-Dyck was evaluated. Reproductive variables included: estrus percentage (EST, %), estrus latency (ESL, hours), ovulation percentage (OP, %), ovulation rate (OR, units), average largest follicle at ovulation (LFO, mm), largest corpus luteum (LCL, mm), embryo number (EBN, units), and embryo implantation percentage (EIP, %). During early May, anestrous mix-breed adult goats (Criollo x Alpine-Saanen-Nubian; n = 38, 26° N) were randomly distributed to (1) Control (CC; n = 12), (2), Non-enriched Opuntia (NEO; n = 14), and (3) Protein-enriched Opuntia (PEO; n = 12). Neither LW (P > 0.05) nor BCS (P > 0.05) or any of the evaluated ovarian variables differed (P > 0.05) among treatments; EST = 89.66%, ESL = 53.66 h, OP = 70.33%, OR = 1.07 units, LFO = 4.5 mm, LCL = 9.6 mm, EBN = 0.94 embryos, and EIP = 48.66%. Irrespective of nutritional supplementation regime, all goats denoted an increased response to the male effect just in the middle of the anestrous season and managed under marginal grazing conditions during the dry season (May to June; 26° N). The use of the male effect successfully invoked neurophysiological pathways to re-activate ovarian follicular and luteal pathways during the natural anestrous season in the female goat. Yet, such successful physiological scenario was not equally exerted to promote an increased embryo implantation rate; this issue claims further consideration. Therefore, it is essential to align not only the peri-conceptional but also the peri-implantation stages to the best suited environmental conditions in the rangeland, in order to increase both reproductive and economic efficiency while promoting sustainability in those rangeland-based marginal goat production systems.

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