A Circular Economy Approach to Integrate Divergent Ruminant Production Systems: Using Dairy Cow Feed Leftovers to Enhance the Out-of-Season Reproductive Performance in Goats

Based on a circular economy approach, we evaluated the possible effect of targeted supplementation with leftover feed from dairy cows (i.e., intensive system) on the reproductive performance of crossbred/rangeland goats (i.e., extensive system) in arid Northern Mexico. During the deep-anestrous season (i.e., March-April, 25° North), multiparous goats (n = 38) with a similar body weight (BW) and body condition score (BCS) were randomly assigned to two groups: (1) supplemented group (SG; n = 19; BCS: 1.76 ± 0.07; BW: 43.7 ± 1.8 kg), receiving 400 g goat d-1 of dairy-cow-feed leftovers prior to grazing; and (2) non-supplemented group (NS; n = 19; BCS: 1.76 ± 0.06; BW: 44.3 ± 2.5 kg). Both groups were directed to the rangeland for a period of ≈8 h. While the experimental period lasted 36 d, the experimental breeding considered 11 d (d0-d10). The anovulatory status of goats was ultrasonographically confirmed on days -20, -10, and -1 prior to male-female interaction. Previously, bucks were separated for 3 weeks from the experimental females and received exogenous testosterone every third day (i.e., 50 mg i.m.) prior to mating. With respect to the response variables, namely BW, BCS, blood glucose levels (BGLs), estrus induction (GIE, %), latency to estrus (LTE, h), estrus duration (ED, h), and luteal tissue volume (LTV, mm), no differences (p > 0.05) occurred between experimental groups. However, the response variables, namely goats ovulating (GO, %; 78.9 vs. 47.3), total number of corpuses luteum (TNCL, n; 27 vs. 13), ovulation rate (OR, n; 1.42 vs. 0.73), multiple ovulation (MO, %; 73.3 vs. 55.5), and pregnancy rate on d 36 (PRd36, %, 68.4 vs. 36.8), favored (p < 0.05) the SG over the NS goats. Our results demonstrate that connecting the circularity of two divergent ruminant production systems (i.e., cow-intensive and goat-extensive) by using dairy cows' feed leftovers as a targeted supplementation strategy in anestrous goats under a marginal-rangeland production system enhanced out-of-season reproductive outcomes (i.e., ovulation rate and pregnancy rate), thus benefiting marginal goat producers and their families.

Targeted Glutamate Supply Boosts Insulin Concentrations, Ovarian Activity, and Ovulation Rate in Yearling Goats during the Anestrous Season

The neuroendocrine regulation of the seasonal reproductive axis requires the integration of internal and external signals to ensure synchronized physiological and behavioral responses. Seasonal reproductive changes contribute to intermittent production, which poses challenges for optimizing goat product yields. Consequently, a significant objective in seasonal reproduction research is to attain continuous reproduction and enhance profitability in goat farming. Glutamate plays a crucial role as a modulator in several reproductive and metabolic processes. Hence, the aim of this study was to evaluate the potential impact of exogenous glutamate administration on serum insulin concentration and ovarian function during the out-of-season period in yearling goats. During the anestrous season, animals were randomly located in individual pens to form two experimental groups: (1) glutamate (n = 10, live weight (LW) = 29.1 ± 1.02 kg, body condition score (BCS) = 3.4 ± 0.2 units) and (2) control (n = 10; LW = 29.2 ± 1.07 kg, BCS = 3.5 ± 0.2), with no differences (p < 0.05) regarding LW and BCS. Then, goats were estrus-synchronized, and blood sampling was carried out for insulin quantification. Ovaries were ultrasonographically scanned to assess ovulation rate (OR), number of antral follicles (AFs), and total ovarian activity (TOA = OR + AF). The research outcomes support our working hypothesis. Certainly, our study confirms that those yearling goats treated with exogenous glutamate displayed the largest (p < 0.05) insulin concentrations across time as well as an augmented (p < 0.05) out-of-season ovarian activity.

Ferulic acid supplementation for 40 days in hair ewe lambs experiencing seasonal heat stress: short-term effects on physiological responses, growth, metabolism, and hematological profile

Free ferulic acid (FA) is a natural compound with antioxidant properties which mitigates the negative effects of cold stress in sheep; however, its impact on thermoregulatory responses in heat-stressed sheep has not been defined. The objective was to evaluate the effects of FA supplementation on physiological responses, serum analyte concentrations, and the hematological profile of heat-stressed hair ewe lambs. Twenty-two Dorper × Katahdin ewe lambs (initial body weight = 23.5 ± 2.8 kg and age = 4 months) were housed in individual pens for 40 days and assigned under a randomized complete block design to the following treatments (n = 11): basal diet with 0 (control) or 250 mg of FA/kg of feed. The FA × sampling day interaction only affected serum concentration of some metabolic hormones; particularly on day 20 of the trial, FA increased (P < 0.01) insulins and the insulin to glucose ratio while decreased (P = 0.05) thyroxine. Overall, supplemental FA did not affect rectal temperature, respiratory rate, most body surface temperatures, feedlot performance, and serum concentrations of metabolites, electrolytes, triiodothyronine, and cortisol. In addition, FA only tended to decrease (P ≥ 0.09) erythrocyte count and plaquetocrit and to increase (P = 0.08) mean corpuscular volume. In conclusion, FA supplementation did not improve the growth nor thermoregulatory capacity of heat-stressed hair ewe lambs. Still, it partially modulated the metabolism to reinforce some energetic adaptive mechanisms when the ambient temperature was ≥ 35 °C.

Multifaceted Interplay among Social Dominance, Body Condition, Appetitive and Consummatory Sexual Behaviors, and Semen Quality in Dorper Rams during Out-Of-Season and Transition Periods

Dorper rams (n = 24) were evaluated during the sexual resting season to determine their social rank (SR), either high (HSR) or low (LSR), under intensive management conditions in northern Mexico (25° N). Aggressive behaviors were quantified during male-to-male interactions, and appetitive and consummatory sexual behaviors during male-to-female interactions. Morphometric, live weight (LW), and body condition score (BCS) were recorded. During the early reproductive season, male-to-female behaviors were newly itemized simultaneously by seminal quality and quantity sampling. Finally, the dependent variables of the hemogram components were also quantified. Neither LW (61.25 ± 2.4 kg) nor morphometric variables differed between SR groups. However, BCS (2.25 vs. 2.66 u), sexual behaviors (i.e., approaches: 59.6 vs. 21.73 n, mating with ejaculation: 77.7 vs. 42.86 %, latency to ejaculation: 16.6 vs. 143.07 s), ejaculate volume (0.57 vs. 0.23 mL), and hemogram components favored the HSR rams (p < 0.05). Moreover, in their first male-to-female interaction, >50% of the LSR rams failed to display any sexual activity. HSR rams displayed a greater number of threatening behaviors, managing to displace LSR rams when exposed to estrus ewes during the male sexual resting season; more sexual behaviors; and an increased seminal volume in a non-live weight-dependent fashion.

Termorregulación y respuestas reproductivas de carneros bajo estrés por calor. Revisión

Las temperaturas elevadas registradas durante la época de verano en las regiones cálidas comprometen la capacidad reproductiva de los animales domésticos. En carneros, el estrés por calor (EC) causa en el organismo una serie de ajustes fisiológicos, metabólicos, endocrinos y moleculares con el objeto de mantener normotermia y sobrevivir; sin embargo, varios de estos cambios se asocian negativamente con su fertilidad, principalmente los endocrinos. El EC en carneros provoca una disminución en las concentraciones sanguíneas de testosterona a través de diferentes mecanismos, y esto se refleja negativamente en el proceso de espermatogénesis y en la conducta sexual. En consecuencia, los carneros estresados por calor presentan baja calidad seminal y apetito sexual; a nivel de espermatozoides se ha observado daño estructural y en el ADN. Dada esta situación, se recomienda el uso de estrategias de mitigación del EC durante el verano en las explotaciones ovinas de regiones cálidas, tales como el uso de sombras en corrales, la administración de antioxidantes o modificaciones en la alimentación. Por lo tanto, el objetivo de este documento es revisar el conocimiento actual en relación al efecto del EC sobre la capacidad de termorregulación y reproductiva de los carneros, así como la aplicación de estrategias para su mitigación.

n-6 Polyunsaturated fatty acids in the feeding of late gestation hair ewes: the effects on thermoregulation, growth, and metabolism of heat-stressed growing lambs

The objective was to determine the effects of feeding soybean oil (SBO), an ingredient rich in n-6 polyunsaturated fatty acids (PUFA), to late gestation hair ewes on physiological responses, feedlot performance, and serum metabolite and electrolyte concentrations of their growing ewe lambs under outdoor heat stress conditions. Twenty-four Dorper × Pelibuey ewe lambs weaned (body weight = 21.5 ± 0.2 kg, age= 2 months, and multiple birth) born from ewes fed 0, 30, or 60 mg of SBO/kg dry matter (DM) during late gestation were selected (n = 8/treatment) to conduct a 30-day feeding trial during the summer season of a desert region (temperature = 34 °C and temperature-humidity index = 35 units). While rectal temperature was unaffected in any daytime, respiratory rate in the afternoon quadratically increased (P = 0.05) as the SBO levels increased from 0 to 60 mg/kg DM in the maternal diet. Final weight, average daily gain, and feed efficiency linearly increased (P = 0.04) with increasing levels of SBO. Body surface temperatures and serum concentration of glucose, cholesterol, triglyceride, total protein, urea, sodium, potassium, and chlorine did not vary by the SBO inclusion in the maternal diet. In conclusion, feeding late gestation hair ewes with source rich in n-6 PUFA appears to be an effective maternal nutritional strategy to improve post-weaning growth without compromising the thermoregulatory ability of their growing offspring under a heat stress environment.

Growth performance and changes in physiological, metabolic and hematological parameters due to outdoor heat stress in hair breed male lambs finished in feedlot

The aim of this study was to evaluate the effect of seasonal heat stress (HS) on productive performance, physiological responses, metabolism, and hematological profile of hair breed male lambs finished in feedlot. Twenty Dorper × Katahdin male lambs (body weight = 34.6 ± 1.4 kg and age = 4.5 months) were housed in individual pens and exposed to environmental conditions of summer HS (n = 10, temperature = 28.3 ± 4.0 °C and THI = 77.2 ± 5.4 units) or winter thermoneutrality (n = 10, temperature = 19.2 ± 2.6 °C and THI = 64.0 ± 3.0 units). Each season, a 30-day feeding test was conducted to measure study variables. Compared to thermoneutral lambs, heat-stressed lambs had lower (P < 0.01) growth rate and feed efficiency without changing dry matter intake. Heat-stressed lambs presented higher (P < 0.01) rectal temperature and respiratory rate through the daytime than termoneutral lambs. On most sampling days, summer HS caused lower (P < 0.01) serum concentrations of glucose, cholesterol, total protein, urea, potassium, and thyroid hormones, but higher (P < 0.01) serum triglyceride and chlorine values. Overall serum concentrations of cortisol and insulin were unaffected by summer HS. The blood of heat-stressed lambs showed lower (P ≤ 0.03) erythrocyte and platelet counts, hemoglobin, and hematocrit, but higher (P ≤ 0.03) erythrocyte size and leucocyte count than the blood of thermoneutral lambs. In conclusion, hair breed male lambs in response to chronic conditions of summer HS had slow growth but avoided hyperthermia due to the activation of physiological, metabolic and endocrine adjustments.

Effect of Social Rank upon Estrus Induction and Some Reproductive Outcomes in Anestrus Goats Treated With Progesterone + eCG

We evaluated the possible role of the social rank [R] (i.e., low-LSR, middle-MSR, or high-HSR) in anestrus goats exposed to a P4 + eCG [D] (i.e., 100 or 350 IU) estrus induction protocol (EIP). Adult, multiparous (two to three lactations), multiracial, dairy-type goats (Alpine-Saanen-Nubian x Criollo goats (n = 70; 25°51' North) managed under stall-fed conditions were all ultrasound evaluated to confirm anestrus status while the R was determined 30 d prior to the EIP. The variables of estrus induction (EI, %), estrus latency (LAT, h), estrus duration (DUR, h), ovulation (OVU, %), ovulation rate (OR, n), corpus luteum size (CLS, cm), pregnancy (PREG, %), kidding (KIDD, %), and litter size (LS, n) as affected by R, D, and the R × D interaction, were evaluated. While OVU and CLS favored (p < 0.05) HSR (96% and + 1.04 ± 0.07 cm), an increased (p < 0.05) LS occurred in D350 vs. D100 (2.06 ± 0.2 vs. 1.36 ± 0.2); neither R nor D affected (p > 0.05; 38.5%) KIDD. However, EI, LAT, DUR, OR, and PREG were affected by the R × D interaction. The HSR group had the largest (p < 0.05) EI % and DUR h, irrespective of D. The shortest (p < 0.05) LAT occurred in D350, irrespective of R. While the largest (p < 0.05) OR occurred in HSR and MSR within D350, the HSR + D350 group had the largest PREG (p < 0.05). These research outcomes are central to defining out-of-season reproductive strategies designed to attenuate seasonal reproduction in goats.

The Opuntia effect and the Reactivation of Ovarian Function and Blood Metabolite Concentrations of Anestrous Goats Exposed to Active Males

Simple Summary

We evaluated the potential supplementation effect of protein enriched Opuntia cladodes, the flat leaf-like steam of cactus species (PEO), upon changes of blood metabolites, estrus induction, estrus latency, and ovulation rate in anestrous goats exposed to sexually active males. We observed that PEO positively influenced reproductive outcomes without changes in blood metabolites. Our results highlight the importance that bio-fortified Opuntia cladodes supplementation exerts on anestrous goats exposed to the male effect as an option to improve not only the out-of-season reproductive efficiency of goats but to enhance the sustainability of marginal, extensive and semi-arid goat production systems.

Abstract

The effect of protein enriched Opuntia cladodes supplementation upon changes of serum total protein, urea, cholesterol, glucose as related to estrus induction (EI%), estrus latency (EL, h), and ovulation rate (OR, units) in adult anestrous goats exposed to the male effect was evaluated. In late April, anestrus goats (n = 45, 25° N) homogeneous regarding live weight (LE; 43.8 ± 1.6 kg) and body condition score (BCS; 2.3 ± 0.1 units) were randomly assigned to: (1). Protein-enriched Opuntia (PEO; n = 15; 29.8% CP, 2.2 Mcal ME kg⁻¹), (2). Non-enriched Opuntia (NEO; n = 15; 6.4% CP, 2.1 Mcal ME kg⁻¹), and (3). Control (CON; n = 15). NEO and PEO goats were individually supplemented with cladodes (160 g d⁻¹; 0900–1000 h), thereafter all groups grazed in a marginal rangeland (1000–1800 h). Neither LW (p > 0.05) nor BCS (p > 0.05) differed among groups, yet an increased (p < 0.05) EI % (100, 57, 42 ± 0.16%), EL h (62, 60, 32 ± 4.2 h), and OR (1.33, 0.71, 0.43 ± 0.23 units) occurred in PEO and NEO vs. CONT, respectively. However, neither blood metabolites differed among groups nor a treatment x time interaction occurred. Peri-breeding protein enriched Opuntia cladodes supplementation of anestrous goats exposed to active males increased (p < 0.01) reproductive outcomes during the non-breeding season.

Relationships of body surface thermography with core temperature, birth weight and climatic variables in neonatal lambs born during early spring in an arid region

The main cause of death in newborn lambs is hypothermia, so is necessary to identify the factors affecting variations in body surface temperatures of sheep neonates because approximately 60% of their body heat losses occur through the skin. This study aimed to establish relationships among body surface thermography from different regions with rectal temperature (RT), birth weight (BW) and climatic variables in hair breed newborn lambs during early spring in an arid region. Data of body surface temperatures measured by infrared thermography (entire head, eye, muzzle, ear, entire body, shoulder, rump, loin, right flank, belly and leg), RT and BW were collected at 0, 12 and 24 h post-lambing in 85 lambs born in early spring. Relative humidity [RH], temperature [Te] and temperature-humidity index [THI] were also recorded. RT was not correlated with surface temperatures at 0 and 24 h, but it was at 12 h with all of them (0.36 ≤ r ≤ 0.44). BW and some surface temperatures were negatively correlated at 0 and 24 h (-0.24 ≤ r ≤ -0.30), but positively at 12 h (0.25 ≤ r ≤ 0.27). All surface temperatures were positively correlated (0.51 ≤ r ≤ 0.85) with Te and THI in the three sampling times. Principal component (PC) analysis showed that PC1 explained the majority of the variance (71-72%), followed by PC2 (8-9%) at 0, 12 and 24 h. Body surface temperatures increased as Te and THI also increased, but decreased with the increase in HR. In conclusion, under early spring environment (predominantly cold), the variations in body surface temperatures of hair sheep neonates were more closely related to climatic variables than to RT and BW. Thermography proved to be an effective tool to determine body heat loss by radiation in skin of neonate lambs.

Ovarian response is not affected by the stage of seasonal anestrus or breed of goats when using a progesterone injection plus human chorionic gonadotropin-based protocol

The aim of this study was to evaluate the effect of the stage of seasonal anestrus and breed on ovarian response in non-estrous cycling goats using a progesterone (P4) injection plus human chorionic gonadotropin (hCG)-based protocol. In Experiment 1, non-estrous cycling local Mexican goats were treated with 20 mg of P4 plus 100 IU of hCG injections 24 h apart during April (early anestrus, n = 13) or June (late anestrus, n = 12). The estrous response, interval from hCG-to-estrus, and interval to ovulation were not affected by season (P > 0.05). In addition, the size of the follicle from which ovulation occurred and the size of the corpus luteum were not different between the two stages of seasonal anestrus (P > 0.05). In Experiment 2, the estrous response was compared between multiparous non-estrous cycling local Mexican (n = 18) and Alpine (n = 19) goats in which stage of the estrous cycle was synchronized using the same P4+hCG protocol as in Experiment 1. Neither the onset of estrus nor the time of ovulation differed between breeds, and the estrus-to-ovulation interval also was similar for both breeds (P > 0.05). The diameter of the dominant follicle at the time of ovulation was similar between local and Alpine goats (P > 0.05). In addition, the pregnancy rate was not different for both local and Alpine goats (P > 0.05). In conclusion, results of this study indicate that the stage of seasonal anestrus or breed do not modify estrous and ovarian response in non-estrous cyclic goats synchronized with a P4 injection plus hCG-based protocol.

Thermoregulatory response to outdoor heat stress of hair sheep females at different physiological state

Forty Dorper × Pelibuey sheep females were used to evaluate the effects of physiological state on physiological variables and serum concentrations of metabolites, thyroid hormones, and electrolytes under outdoor heat stress conditions. Females were selected as follows (n = 10 per group): weaning ewe lambs (WEL; 3 months old), replacement nulliparous ewes (RNE; 8 months old), non-pregnant and non-lactating multiparous ewes (NME; 3-4 years old) and lactating multiparous ewes (LME; 3-4 years old). While physiological variables were measured both morning and afternoon, blood samples were collected before feeding in the morning to determine all blood components. Three contrasts were constructed: (1) WEL vs. older ewes, (2) RNE vs. multiparous ewes, and (3) NME vs. LME. Compared with older ewes, WEL had higher (P < 0.01) rectal temperature (RT) and hair coat temperatures through the day, and also higher (P < 0.01) respiratory rate (RR) only in the afternoon. Serum levels of glucose and cholesterol were lower (P ≤ 0.02) in WEL than in older ewes. Nulliparous ewes compared with multiparous had always similar RT but higher (P ≤ 0.05) hair coat temperatures in most of the body regions by the morning and higher (P < 0.01) RR, without difference for hair coat temperatures in the afternoon. Only serum glucose (P = 0.07) and urea nitrogen (P < 0.01) levels were affected by parturition number, being lower in multiparous ewes. Regarding the effect of lactation, while RR was unaffected, afternoon RT and hair coat temperatures in most of the body regions through the day were higher (P ≤ 0.03) in lactating ewes. In addition, LME had lower (P < 0.01) serum levels of glucose, cholesterol, and urea nitrogen, but higher (P = 0.02) triiodothyronine levels than NME. In conclusion, ewe lambs and lactating ewes were less tolerant to heat stress, while nulliparous and multiparous ewes showed similar thermoregulatory ability.

The use of female estrogenized goats as sexual stimulator of crossbred dairy males subsequently exposed to acyclic goats during two phases of the anestrous season

This research evaluated the possible influence of exposure of male goats to estrogenized female goats ("female effect") upon males' sexual behavior [appetitive (ASB) & consummatory (CSB)], as well as the induction of reproductive activity of crossbred dairy female goats exposed to such treated males ("male effect") during the early and deep anestrous periods. Crossbred dairy adult male goats (n = 12; 24-48 mo. old) and 80 anovulatory crossbred dairy adult female goats (34-50 mo. old) were used during two experimental periods: March to April and April to May. First, males were separated into four groups (n = 3 each), roughly homogeneous regarding body weight and body condition score and randomly assigned to four experimental groups. The first two groups included males + estrogenized females, then such males were exposed to anestrous females either during March (group 1: three males; 20 females; EFEM-MAR), or during April (group 2: three males; 20 females; EFEM-APR). The second two groups were respective control groups: Males + non-treated-anestrous females, and then such males exposed to acyclic females either during March (group 3: three males; 20 females; CONT-MAR) or April (group 4: three males; 20 females; CONT-APR). Once the male-to-female contact was established, both odor (ODT) and behavior (BEHT) tests (2 d × 2 h) were performed during both anestrous periods. On day 10 after introduction of the males, in both anestrous periods, one ultrasonography scanning ("US") was performed to quantify the presence, number and size of corpus luteum (US-CL) to determine the effectiveness of the "male effect" and indicators of ovarian activity. Then, on day 45 after introduction of the males, a second US was performed to evaluate pregnancy rate (US-PREG). The EFEM-males, regardless of the phase of the anestrous cycle, had an increased (P < 0.05) odor intensity with respect to the control groups. In addition, while an increased (P < 0.05) ASB occurred in the EFEM-males, no CSB differences (P > 0.05) arose when treatments were compared, neither in March-April nor in April-May. The EFEM-males exposed to acyclic goats in March-April (i.e. early anestrous period), promoted not only the largest estrus and ovulatory responses (P < 0.05), but also the largest pregnancy rate (P < 0.05) in these previously anestrus goats, suggesting that in April-May (i.e. profound anestrous), the presence of active males was not enough to completely suppress cyclic reproductive arrest. This study generates interesting out-of-season reproductive outcomes in a goat population with a large proportion of highly seasonal dairy breeds (i.e. Alpine, Saanen and Toggenburg), augmenting the possibility to expand milk production and the economic income of goat producers across the year. Besides, this practice may serve as an interesting reproductive tool to increase the sustainability of marginal goat production systems under semiarid conditions.

Effects of pre-lambing maternal energy supplementation on post-weaning productive performance and thermoregulatory capacity of heat-stressed male lambs

Nutritional requirements of sheep during late gestation increase as a consequence of high fetal growth, mammary tissue development and colostrum synthesis. While prepartum energy supplementation is a nutritional strategy to improve lamb postnatal performance in thermoneutral environments, this has not been studied under heat stress. This study aimed to evaluate effects of maternal energy supplementation during the last third of pregnancy on post-weaning feedlot performance and thermoregulation capacity of heat-stressed male lambs born from multiple births. Twenty Dorper x Pelibuey entire male lambs with initial body weight of 18.2 ± 0.4 kg, aged 2.7 mo (weaned) and born in multiple pregnancies were used in a 32 d feeding study. Treatments were based in the prenatal origin of the lambs: 1) ewes fed 100 (n = 10, Control) and 2) 125% (n = 10, Supplemented) of metabolizable energy requirements from day 100 of gestation to lambing. Lambs were housed outdoor in individual pens under summer environment conditions in an arid region (temperature = 36 ± 4.4 °C and temperature-humidity index = 81 ± 3.9 units). Overall feedlot performance was not affected by pre-partum maternal feeding, although lower (P = 0.04) growth rate and feed efficiency occurred during the last 8 d of the study in lambs born from supplemented ewes. Rectal temperature, respiratory rate and hair coat temperature during daytime were unaffected by prepartum supplementation. Serum concentrations of glucose, cholesterol, urea, total protein and thyroid hormones were similar between lambs born from control and supplemented ewes. It is concluded that, in hair sheep breeds, prepartum energy supplementation did not alter overall post-weaning productive performance and thermoregulation capacity of heat-stressed male lambs that were born in multiple pregnancies.

Influence of sexual behavior of Dorper rams treated with glutamate and/or testosterone on reproductive performance of anovulatory ewes

The aim of this study was to determine if exogenous administration of glutamate and (or) testosterone to male rams during the season of reproductive arrest is able to re-activate male sexual behavior and, later on, to promote through the male effect, both sexual and reproductive competence of anovulatory nulliparous ewes. Therefore, an experiment was performed under long-day photoperiods (spring; photo-reproductive arrest, 26°N). Dorper rams were randomly divided into four homogeneous experimental groups (n = 5 males each) regarding live weight (LW), body condition score (BCS), scrotal circumference (SC) and odor intensity (OI). Then, groups were treated with: i) GG (7 mg kg^-1 LW of glutamate, every 4d × 30d, im.), ii) GGT (7 mg kg^-1 LW of glutamate every 4d × 30d im + 25 mg of testosterone propionate, every 3d × 15d, im.), iii) GT (25 mg of testosterone propionate every 3d × 15d, im, and iv) GC (1 mL of saline, every 4d × 30d, im.). Thereafter, Dorper rams, (n = 4 per group) were selected and exposed to Dorper anovulatory-nulliparous ewes divided in four groups (n = 14 ewes each), and all the appetitive (ASB) and consummatory (CSB) sexual behaviors and indicators of sexual rest (ISR) were registered during the first 48 h of this male-to-females contact. Thereafter, males continued the male-to-female contact for another 8 d, in order to quantify the ewe's sexual and reproductive response through the male effect. During the sexual behavior tests, the GGT rams showed the highest ASB + CSB frequencies (P < 0.05) followed by the GG-rams with the lowest frequencies showed by the GC and GT groups. While the highest ISR behaviors were shown by the GG and GGT groups (P < 0.05) followed by the GC and GT-rams, no differences occurred regarding LW, BCS, and SC along the experimental breeding, with the largest (P < 0.05) OI shown by the GGT-rams and the lowest value observed in the control rams. Regarding the reproductive response of the nulliparous-anovulatory ewes exposed to treated rams, the glutamate + testosterone treated males induced not only an increased (P < 0.05) ovulatory activity and faster (P < 0.05) estrus response but an augmented (P < 0.05) pregnancy rate of the previously anovulatory ewes. To conclude, whereas the GG and GGT treatments generated encouraging sexual and reproductive outcomes, our results are also thought-provoking from a comparative sexual behavior perspective while may embrace potential applications to other animal industries.

Maternal undernutrition during the pre- and post-conception periods in twin-bearing hairsheep ewes: effects on fetal and placental development at mid-gestation

To evaluate the effects of pre- and post-conception undernutrition (UN) on fetal and placental development at mid-gestation, 28 Katahdin × Pelibuey multiparous ewes were blocked by weight and assigned to the following four dietary treatments (n = 7 each): ewes fed 100% (control) or 60% of their nutritional requirements 30 days before mating (UNPre), 50 days after mating (UNPost) or during both periods (UNB). Four twin-bearing ewes were selected per treatment at day 50 post-conception and then slaughtered at day 75 of gestation to analyze their fetuses. Control fetuses were heavier (P < 0.05) than UNPost and UNB fetuses in 14.6 and 9.4%, respectively. Organ weights as percentage of the fetal weight (except for liver) and morphometric measurements (except for abdominal girth) were similar between control and UN fetuses (UNPre, UNPost, and UNB). Placental mass was heavier (P < 0.05) in control ewes than UNB ewes, but not relative to ewes of other treatments. The number of placentomes per ewe and placental efficiency were unaffected by UN treatments. Compared to control, only UNB ewes exhibited variations (P < 0.05) in the proportion of placentomes, specifically for type A (+13.8%) and B (-12.6%). Placentomes of type A and B had lower weight, length, and width of placentas in UNPost and UNB ewes than placentas of control ewes (P < 0.05). Overall results indicate that fetal and placental development of ewes carrying twins is mainly altered when nutritional restriction occurs simultaneously before conception and during the first third of pregnancy.

Appetitive and Consummatory Sexual Behaviors of Rams Treated with Exogenous Testosterone and Exposed to Anestrus Dorper Ewes: Efficacy of the Male Effect

We determine whether Dorper rams treated with testosterone in the sexual resting season trigger both appetitive and consummatory sexual behaviors and sexual and reproductive outcomes in anestrous ewes at 26° North during March-April. Dorper rams (n = 12, 2.5 years) were randomly divided prior to mating in two groups: GT (treated group; n = 6), treated with testosterone propionate (25 mg i.m. every 3 days × 3 weeks) and GC (control group; n = 6), treated with saline. Thereafter, adult anovulatory Dorper ewes (n = 61) were exposed to the GT-rams while the other group (n = 60) was exposed to the GC-rams. Ram's appetitive sexual behavior was similar (50 %) in both groups, yet the GT-rams exerted 100 % of the consummatory sexual behavior. Sexual and reproductive outcomes of the anestrus females exposed to both male groups considered two phases: 0-15 and 16-25 days from exposure to males. Involved variables were: ewes in estrus, ewes ovulating, duration of estrus, pregnant ewes, and lambed ewes. All the average variables favored those ewes exposed to GT-males: ewes in estrus: 85 versus 40 %; ewes ovulating: 80 versus 53 %; duration of estrus: 37 versus 25 h; pregnant ewes: 60 versus 31 %, and lambed ewes: 57 versus 31 %. Results confirm that adult Dorper rams treated with exogenous testosterone had improved consummatory sexual behavior and induced increased ovulation and pregnancy rates when exposed to anestrus ewes. This feasible and inexpensive testosterone-based protocol through the male effect also enhanced both sexual and reproductive outcomes in previously anestrous Dorper ewes during the natural out-of-season. Results are important to speed up reproductive performance of sheep during the natural anestrous season at this latitude, while also they embrace interesting outcomes from a comparative sexual behavior stand point.

Effects of seasonal ambient heat stress (spring vs. summer) on physiological and metabolic variables in hair sheep located in an arid region

Twenty Dorper × Pelibuey primiparous ewes were used to evaluate effects of seasonal ambient heat stress (i.e., spring vs. summer) on physiological and metabolic responses under production conditions in an arid region. Ten ewes experiencing summer heat stress (i.e., temperature = 34.8 ± 4.6 °C; THI = 81.6 ± 3.2 units) and 10 under spring thermoneutral conditions (temperature = 24.2 ± 5.4 °C; THI = 68.0 ± 4.8 units) were corralled together to measure rectal temperature, respiratory frequency, and skin temperatures at 0600, 1200, 1800, and 2400 h on four occasions over 40 days. Blood metabolite and electrolyte concentrations were also measured at 0600 and 1800 hours. Data were analyzed with a completely randomized design using repeated measurements in time. Rectal and skin temperatures, as well as respiratory frequency, were higher (P < 0.01) in summer than spring at all measured days. Blood serum glucose, cholesterol, triglycerides, and chlorine concentrations were lower (P < 0.01) in summer than spring at 0800 and 1800 hours. In contrast, summer heat stress increased (P < 0.01) blood urea and potassium concentrations at 0800 and 1800 hours. Compared with spring thermoneutral conditions, summer heat stress affected the physiological and metabolic status of hair breed ewes in an arid region, which included blood metabolite and electrolyte adjustments to efficiently cope with summer heat stress.

Reproductive outcomes of Alpine goats primed with progesterone and treated with human chorionic gonadotropin during the anestrus-to-estrus transition season

This study aimed to determine the possible effects of a single injection of human chorionic gonadotropin (hCG) as a means for estrus induction in acyclic French-Alpine goats during the reproductive transition period at 25°N, 103°W. The potential effects of hCG upon ovarian function and reproductive performance of goats were also assessed. Multiparous acyclic French-Alpine goats (n = 39; 37.4 ± 8 .5 kg) were primed with 20mg progesterone (P4) 1 day prior to hCG administration. Thereafter, does were treated either with saline (hCG-0; n = 10), 50 (hCG-50; n = 9), 100 (hCG-100; n = 10), or 300 IU of hCG (hCG-300; n = 10). Ovarian structures and pregnancy were monitored by transrectal ultrasonography. In addition, after hCG application, goats were monitored twice daily (0800 and 1800 h) to detect estrus signs, with the use of aproned, sexually active bucks treated with testosterone. Goats were bred 12h after the onset of estrus. Two days after hCG administration, the number of large follicles was higher (P < 0.05) in the hCG-50 and hCG-300 groups (1.7 ± 0.1 and 1.8 ± 0.2, respectively) compared with the hCG-100 and hCG-0 groups (1.4 ± 0.2 and 1.1 ± 0.1, respectively). Although none of the hCG-0-goats depicted estrus, the estrus response from the hCG-50, hCG-100, and hCG-300 groups over the 7-d breeding period was 67%, 100%, and 90%, respectively (P > 0.05), being always accompanied by ovulation. Pregnancy rate (67, 100, and 70%), kidding rate (55%, 80%, and 70%), and litter size (1.6 ± 0.5, 1.5 ± 0.5, and 1.5 ± 0.5) for hCG-50, hCG-100, and hCG-300, respectively, did not differ among the hCG-treated does. Therefore, the combined use of P4-priming plus a 100-IU hCG injection is an effective protocol for inducing estrus in non-cycling Alpine goats during the anestrus-to-estrus transition period, which is of key importance for both goat producers and industrializers.

Effects of free ferulic acid on productive performance, blood metabolites, and carcass characteristics of feedlot finishing ewe lambs

The aim of this study was to evaluate effects of free ferulic acid (FA) supplementation on productive performance, some blood metabolite concentrations, and carcass characteristics of ewe lambs finished in a feedlot. Dorper×Pelibuey ewe lambs (n=20; BW=28.5±0.5 kg; age=5 mo) were individually housed in pens and assigned under a randomized complete block design to the following dietary treatments (n=10): daily feeding without (control) or with 300 mg of FA/animal. The feedlot feeding period lasted 34 d and then all ewe lambs were slaughtered. Free FA did not affect (P≥0.16) BW gain, ADG, DMI, and G:F during the first 17 d, but BW gain (P=0.10) and ADG (P=0.10) tended to decrease for FA from d 17 to 34 and from d 1 to 34 without affecting (P≥0.16) DMI and G:F in ewe lambs. Serum concentrations of glucose, cholesterol, triglyceride, total protein, and urea were not affected (P>0.05) by FA at d 1, 17, and 34 of the feeding period. Carcass characteristics were not affected (P>0.05) by FA. Stomach percentage tended (P=0.08) to decrease and leg yields increased (P=0.02) for FA. Other noncarcass components and wholesale cut yields were not affected (P>0.10) by FA. In conclusion, FA supplementation did not improve productive performance, metabolic status, and carcass characteristics of ewe lambs receiving a feedlot finishing diet.

Glutamate supply positively affects serum cholesterol concentrations without increases in total protein and urea around the onset of puberty in goats

Different neurotransmitter and neuromodulatory systems regulate synthesis and secretion of GnRH. Whereas the endocrine and neural systems are activated in response to the metabolic status and the circulating levels of specific blood metabolites, glutamate receptors have been reported at hepatic level. This study evaluated the possible effect of glutamate supplementation upon changes in serum concentrations across time for total protein (TP), urea (UR) and cholesterol (CL) around the onset of puberty in goats. Prepuberal female goats (n=18) were randomly assigned to: (1) excitatory amino acids group, GLUT, n=10; 16.52±1.04kg live weight (LW), 3.4±0.12 body condition score (BCS) receiving an i.v. infusion of 7mgkg(-1) LW of l-glutamate, and (2) Control group, CONT, n=8; 16.1±1.04kg LW, 3.1±0.12 BCS. General averages for LW (23.2±0.72kg), BCS (3.37±0.10 units), serum TP (65.28±2.46mgdL(-1)), UR (23.42±0.95mgdL(-1)), CL (77.89±1.10mgdL(-1)) as well as the serum levels for TP and UR across time did not differ (P>0.05) between treatments. However, while GLUT positively affected (P<0.05) both the onset (207±9 vs. 225±12 d) and the percentage (70 vs. 25%) of females showing puberty, a treatment×time interaction effect (P<0.05) was observed in the GLUT group, with increases in serum cholesterol, coincident with the onset of puberty. Therefore, in peripuberal glutamate supplemented goats, serum cholesterol profile could act as a metabolic modulator for the establishment of puberty, denoting also a potential role of glutamate as modulator of lipid metabolism.

Short-term beta-carotene-supplementation positively affects ovarian activity and serum insulin concentrations in a goat model

In early October 2010, adult goats (no.=22, 3.5 yr old, 7/8 Sannen-Alpine, 26° N, 103° W, at 1117 m), were randomly assigned to: i) beta-carotene group (BC) [no.=10; live weight (LW)=45.9±1.97 kg, body condition score (BCS) =3.04±0.08; orally supplemented with 50 mg of BC per goat per day]; ii) control group (CONT) (no.=12; LW=46.2±2.04 kg, BCS=3.0±0.08). Animals received a basal diet of alfalfa hay, corn silage, and corn grain, having free access to water, shade, and mineral salts. During the second half of October, estrus was synchronized by using intravaginal sponges. Thereafter, by mid-follicular phase, an intensive blood sampling (6 h × 60 min) was performed to evaluate serum insulin concentrations (INS) by radioimmunoassay. By the end of the luteal phase, an ultrasonographic scanning was performed to evaluate total ovarian activity (TOA) [TOA=total follicles (TF) + total corpus luteum (TCL)]. The whole experimental period consisted of 34 days pre- and 17 days post-ovulation, for a total of 52 days. Average LW and BCS did not differ (p>0.05) during the experimental period. Nonetheless, increases in TF no. (5.0 vs 3.4±0.6 units; p=0.05), TCL no. (3.4 vs 2.8±0.2 units; p=0.05), TOA (8.1 vs 6.2±0.6 units; p=0.05) and INS (4.6 vs 3.9±0.4 ng ml-1; p=0.05) favored to the BC-supplemented group. A positive correlation between LW (r(2)=0.42; p=0.04) and BCS (r(2)=0.47; p=0.02) with respect to ovulation rate, was detected. BC-supplementation increased ovarian activity in the female goat while positively affected the release pattern of insulin, suggesting a potential role of BC as a central and/or pancreas-activating molecule in adult goats; such results may hold not only physiologic but also clinical significance.

Betacarotene supplementation increases ovulation rate without an increment in LH secretion in cyclic goats

This study aimed to evaluate the effects of betacarotene (BC) supplementation on ovulation rate (OR) and luteinizing hormone (LH) secretion in adult goats during the breeding season. Additionally, total ovarian activity (TOA) comprising the total number of ultrasonographically detectable antral follicles (AF) and corpora lutea (OR) was also assessed. In early October, adult goats [n=22, 3.5 years of age, 7/8 Sannen-Alpine; 26°N, 103°W at 1117m.a.s.l.] were randomly assigned to: (i) BC group (BCG), orally supplemented with 50mg of BC/goat/day [n=10; live weight (LW)=45.9±2.0kg, body condition score (BCS; range: 0-emaciated to 5-obese)=3.0±0.1], and (ii) control group (CONT) [n=12; LW=46.2±2.0kg, BCS=3.0±0.1]. All animals received a basal diet of alfalfa hay, corn silage and corn grain, with free access to water and mineral salts. The whole experimental period spanned 34 days before and 17 days after ovulation. On day 23 of the experiment, estrus was synchronized with progestin-releasing intravaginal sponges; 36h prior to estrus, an intensive blood sampling (every 15min for 6h) was performed to determine mean LH concentrations, pulsatility (LH-PULSE) and area under the curve (LH-AUC) for serial LH concentrations. Afterwards, by the end of the luteal phase (i.e., 17 days after the onset of estrus), an ultrasonographic scanning was performed to evaluate OR and TOA [AF+OR]. The average LW and BCS did not differ (p>0.05) during the experimental period. BC-supplemented goats showed an increase in OR (3.4±0.2 versus 2.8±0.2; p<0.05) and exhibited lower (p<0.05) serum LH concentrations, LH-AUC and LH-PULSE compared to CONT. A positive correlation was recorded between OR and LW (r(2)=0.42, p<0.05) and BCS (r(2)=0.47, p<0.05). In addition, AF (5.0±0.6 versus 3.4±0.6) and TOA (8.4±0.6 versus 6.2±0.6) were greater (p<0.05) in the BC-supplemented group than CONT. Supplementation with BC enhanced ovarian follicular development and ovulation rate in adult female goats under decreased photoperiods through LHRH-independant pathways or direct effects of BC on ovarian function.

Long-term betacarotene-supplementation enhances serum insulin concentrations without effect on the onset of puberty in the female goat

The effect of betacarotene (BC) supplementation on the onset of puberty and serum insulin levels in goats was evaluated in the study. In June, prepuberal goats (n=17; 3 months old; 7/8 Saanen-Alpine; 26° NL) were randomly assigned to one of two groups: 1/ betacarotene group supplemented daily with 50 mg of BC (n=9; live weight [LW]: 17.3±1.0 kg; body condition score [BCS]: 3.34±0.12) or 2/ control group (CONT; n=8; LW:16.1±1.0 kg; BCS=3.17±0.12). From June to November, an intermittent blood sampling was performed twice per week in both groups to evaluate serum progesterone (P(4)), while monthly samples were intended for insulin (INS) determination. Initial mean LW (16.7±1.0 kg) and BCS (3.31±0.12) were similar (p>0.05) in both groups. Mean serum insulin (1.37 vs. 1.18±0.09 ng/ml), age of puberty (215.7 vs. 226.5±6.6 days) and the percentage of goats reaching puberty (44.4 vs. 25.0±17.0%) did not differ (p>0.05) between BC and CONT group, respectively. However, increase in serum insulin during the second half of the experiment was observed in BC group (p<0.05) which was positively correlated with LW (r=0.95; p<0.05). In addition, as LW (r=-0.89) and serum insulin (r=-0.76) levels increased, the natural photoperiod decreased, revealing negative correlations (p<0.05) between the respective variables. In this study, BC supplementation did not promote precocious puberty and did not affect the percentage of goats reaching activation of the hypothalamic-hypophyseal-gonadal axis during the establishment of puberty. Nonetheless, BC supplementation positively affected the release pattern of insulin suggesting a potential role of BC as pancreas-activating molecule.

Effect of nutritional supplementation upon pregnancy rates of goats under semiarid rangelands and exposed to the male effect

The aim of this study was to evaluate possible effects of improved protein and energy diet upon reproductive outcomes of adult goats under marginal rangeland grazing conditions and exposed to the male effect during the anoestrous-dry season. Adult goats (Nubian × Criollo, nonpregnant, nonlactating, n = 160, 22° 50' N, 100° 59' W, 1,653 m) were randomly divided in two experimental groups: Control (CG; n = 80) and Supplemented (SG; n = 80). Both CG and SG goats were kept together during the day for ranging a semiarid rangeland while separated accordingly at night. SG goats were individually supplemented [400 g kg(-1) day(-1); 14% CP and 2.92 Mcal DE kg(-1)] during a 30-day period. Thereafter, both the CG [35.5 ± 0.94 kg LW, 1.95 ± 0.06 U, body condition score (BCS)] and the SG [39.5 ± 0.94 kg LW, 2.29 ± 0.06 BCS] were exposed to adult males (Nubian, n = 4, two per group) of proven libido and fertility and kept together at night (1700-0900) during a 42-day experimental breeding period. At the beginning of the breeding period, both LW (P < 0.001) and BCS (P < 0.001) were higher in the SG, which was also reflected in higher pregnancy rate (92.5 vs. 76.3%, P < 0.01). Nonetheless, both CG and SG depicted an increased abortion rate (52.5 vs. 41.9% P > 0.05), respectively. Results suggest that nutritional supplementation and the male effect were able to successfully invoke neurophysiological pathways to increase ovarian activity and to promote a uterine milieu prone to the establishment of pregnancy during the anoestrus season. However, the increased abortion rates observed in the study occurred irrespective of the nutritional regime offered during the premating stage. Therefore, there is a need to align the last third of gestation to the onset of the grazing season in order to increase reproductive and economic efficiency in those rangeland-based marginal goat production systems.

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

This experiment was conducted to evaluate the effect of administering hormonal treatments (melatonin and progestagen/equine chronic gonadotropin (eCG)) on advancing puberty in Awassi ewe lambs. Fifty-one 6-month-old ewe lambs of similar body weights (around 28 kg) were randomly assigned into four treatment groups; control (CON; n = 14), melatonin (MEL; n = 13), melatonin plus progestagen-eCG (MELPP; n = 11), and progestagen-eCG (PP; n = 13). Ewe lambs in the PP and MELPP groups were fitted with intravaginal progestagen sponges containing 60 mg medroxyprogesterone acetate for 14 days; 400 IU eCG were administered to each of these ewe lambs on the day of sponge removal. Ewe lambs in the MEL and MELPP groups received subcutaneous melatonin implants (Regulin®, 18 mg melatonin) 36 days before sponge insertion. Hormonal treatment had no effect on ewe lamb body weight change. Estrous behavior was greater (p < 0.001) in the PP and MELPP groups than in the CON and MEL ewe lambs. The duration from ram introduction to onset of estrus was shorter (p < 0.05) in the CON, PP, and MELPP than in the MEL ewe lambs. The number of ewe lambs showing luteal activity was greater (p < 0.001) in the MELPP and PP than in the CON and MEL groups. Lambing rate from mating during the first cycle following ram introduction differed significantly (p < 0.01) among treatments being greater in the MELPP and PP than in the CON and MEL groups. Based on these results, it can be concluded that progestagen-eCG appears to be more effective than melatonin in inducing reproductive activity. However, the majority of ewe lambs in the current study either failed to cycle or stopped cycling following the induced estrus. Such failure in advancing puberty may be related to body weight of ewe lambs at the time of mating.

The effect of flushing and stimulus of estrogenized does on reproductive performance of anovulatory-range goats

This study was conducted to determine whether flushing or the stimulus of estrogenized goats is necessary to achieve a high reproductive response in anestrous goats on rangeland. Does were feed-supplemented on rangeland (flushed, n = 20). Other group was exposed to estrogenized does during the mating period (stimulated, n = 20). A third group was both supplemented and stimulated (stimulated-flushed, n = 20) and other group grazed on rangeland only (control, n = 18). More goats in the stimulated and stimulated-flushed groups showed estrus during the first 5 days of joining (45% and 60%, respectively) than the control and flushed groups (11% and 5%, respectively; P < 0.05). Flushing did not improve prolificacy and reduced (P < 0.05) kidding rates (40% and 35% for the flushed and stimulated-flushed groups, respectively) compared to 67% and 55% for the control and stimulated groups, respectively. This experiment demonstrates potential shortcomings of use of flushing in range goats with inadequate nutrition during gestation.

Glutamate supply positively affects serum release of triiodothyronine and insulin across time without increases of glucose during the onset of puberty in female goats

The current study evaluated the effect of glutamate supply on the onset of puberty and possible links to changes in serum concentrations of insulin [INS], glucose [GLU] and triiodothyronine [T(3)]. The study was conducted from June to November in prepuberal female goats (n=18; 3 mo. old, 7/8 Saanen-Alpine, 1/8 Criollo, 26° north) randomly assigned to two experimental groups: (i) excitatory amino acids group (group AA, n=10; 16.52±1.04 kg LW, 3.4±0.12 body condition score [BCS], receiving an intravenous infusion of 7 mg kg(-1) live weight [LW] of l-glutamate, twice a week, and (ii) control group (group CC, n=8; 16.1±1.04 kg LW, 3.1±0.12 BCS) receiving saline. Blood samples were obtained twice a week, for assessing progesterone [P(4)], as well as in a monthly basis to evaluate INS and T(3) by RIA. Mean final LW and BCS were 23.2±0.72 kg, 3.53±0.10 units, without differences between groups. The AA group depicted an earlier onset of puberty (6.9±0.3 compared to 7.5±0.4 mo.; P<0.05) and an increased ovarian activity (70±0.28% compared to 25±0.26%; P<0.05). Neither serum INS concentrations nor serum glucose concentrations differed between treatments (1.2±0.06 ng mL(-1) and 89.6±1.8 mg 100 mL(-1); P>0.05, respectively). Serum T(3) concentrations, however, were greater in AA goats (1.55±0.03 compared to 1.39±0.04 ng mL(-1)). In addition, a treatment x time interaction occurred (P<0.05) across the experimental period for both T(3) and INS, with increases by the last third of the experimental period, time at which the onset of puberty occurred in both experimental groups. No differences (P>0.05) for glucose concentrations across time occurred between treatments. Results indicate that, in prepuberal goats, glutamate acts as a cue for sexual maturation in a glucose-independent pathway, while both T(3) and INS seem to act as metabolic modulators for the establishment of puberty in goats. Actions of INS and T(3) are mediated directly on hypothalamic centers regulating the pulsatile release of GnRH or indirectly by peripheral cues reflecting INS-T(3) actions on somatic development remains to be determined.

Relationship between litter birthweight and litter size in five goat genotypes

The aim of the present study was to use a non-linear regression approach to investigate the relationship between litter birthweight and litter size of five breeds of goat under intensive conditions in a hot arid environment. Litter-size and litter-weight data on 20 117 kids from 13 685 litters representing five breeds, namely Saanen, Toggenburg, French Alpine, Anglo-Nubian and Granadina, were compared to evaluate this relationship. Regardless of breed, birthweight for kids born as twins, triplets and quadruplets was, on average, 92%, 87% and 83%, respectively, of that of singleton kids; litter size accounted for 81% of the variation in litter weight. The coefficient of the power regression differed (P < 0.01) among breeds, with similar slopes for French Alpine, Toggenburg and Saanen goats and a smaller litter-weight increase for every additional fetus in Anglo-Nubian and Granadina goats than in other breeds of goat. These results support the hypothesis that, regardless of parity, litter weight in dairy and Granadina goats increases at a reduced rate with increases in litter size, although the rate of change with the increasing number of fetuses was moderate, as indicated by a power regression of the form y = axb between these variables across age categories and breeds of goat.

Erratum to: Relationship between litter birthweight and litter size in five goat genotypes

The aim of the present study was to use a non-linear regression approach to investigate the relationship between litter birthweight and litter size of five breeds of goat under intensive conditions in a hot arid environment. Litter-size and litter-weight data on 20�117 kids from 13�685 litters representing five breeds, namely Saanen, Toggenburg, French Alpine, Anglo-Nubian and Granadina, were compared to evaluate this relationship. Regardless of breed, birthweight for kids born as twins, triplets and quadruplets was, on average, 92%, 87% and 83%, respectively, of that of singleton kids; litter size accounted for 81% of the variation in litter weight. The coefficient of the power regression differed (P < 0.01) among breeds, with similar slopes for French Alpine, Toggenburg and Saanen goats and a smaller litter-weight increase for every additional fetus in Anglo-Nubian and Granadina goats than in other breeds of goat. These results support the hypothesis that, regardless of parity, litter weight in dairy and Granadina goats increases at a reduced rate with increases in litter size, although the rate of change with the increasing number of fetuses was moderate, as indicated by a power regression of the form y = axb between these variables across age categories and breeds of goat.

Relative roles of photoperiodic and nutritional cues in modulating ovarian activity in goats

The objective of the current study was to evaluate the influence of nutrition and its interaction with the photoperiod on the ovarian activity of Criollo goats. In early February (22 degrees NL, anestrous season) goats were randomly assigned to the two experimental groups: high (HN; n=10) and low (LN; n=10) nutrition goats. The HN group was fed in mixed prairies with grass and clover (17.3-/+7.5% of crude protein, CP; 66.3-/+5.7% dry organic matter, DOM) and received 150 g of concentrate (12% CP) per goat and day. The LN group received only corn stubble (6.2-/+0.7% CP, 53.7-/+1.9% DOM). Serum progesterone (P(4)) and triiodothyronine (T(3)) concentrations were measured (RIA) at three selected periods of seasonal anestrous: early (8-24(th) March), mid (13(th) April - 3(rd) May) and late (26(th) May - 14(th) June) anestrous. Body weight, body condition and body condition index were determined at the beginning of the study and every 14 days. Body weight was positively correlated with serum T(3) (r=0.704; p<0.05). The percentage of cycling does during the three examined periods was higher (p<0.05) in the HN group than in the LN group (80 vs. 30%, 80 vs. 20%, and 60 vs. 10%, respectively). The high nutrition level increased reproductive activity of Criollo goats during all three periods of the anestrous season including deep anestrous.

High periconceptional protein intake modifies uterine and embryonic relationships increasing early pregnancy losses and embryo growth retardation in sheep

The effects of supplemented protein level (PL) during the periconceptional period and their interaction with body condition were evaluated in sheep. Multiparous Rambouillet ewes (n = 12) received two PL of rumen undegradable protein (UIP) during a 30-day pre-mating and 15-day post-mating period: low [LPL, 24% crude protein (CP), 14 g UIP and 36 g/CP animal/day] and high [HPL, 44% CP, 30 g UIP and 50 g/CP animal/day]. While ovulation rate (OR) did not differ between treatments (1.6 +/- 0.5, mean +/- SEM), a lower fertility rate, a decreased embryo number and a reduced uterine pH (UpH) was observed in the HPL group (p < 0.05), irrespective of BC. Luteal tissue weight, volume and progesterone secretion did not differ among treatments. Sheep with lower UpH also had lower conceptus weight (Cwt; p < 0.05, r = 0.65) and conceptuses with lower mass tended to secrete less INF-tau and IGF-1, and the correspondent endometrial explants had a higher basal PGF(2alpha) release. Current study indicates that high protein diets during the periconceptional period in sheep modify uterine and embryonic relationships, increasing early pregnancy losses and inducing embryo growth retardation. Surviving embryos were affected by weight reductions, which could compromise later foetal growth and birth weight. Results evidence the key role of a balanced diet in reproductive success and indicate that the quality and nutrient composition of the maternal diet are essential for an adequate establishment of pregnancy, having paramount effects on the interplay of the embryo and the uterus.

Short-term intake of beta-carotene-supplemented diets enhances ovarian function and progesterone synthesis in goats

The effect of beta-carotene supplementation upon luteal activity, measured as number (CLT) and volume (VLT) of corpus luteum, and P4 synthesis in goats, was evaluated. Goats (n = 22, 34 months) were randomly assigned to one of two experimental groups: (i) beta-carotene [Beta, n = 10; body weight (BW = 44.8 +/- 1.45 kg), body condition score (BCS = 3.25 +/- 0.07)], and (ii) Control (Control, n = 12; BW = 45.30 +/- 1.32 kg, BCS = 3.33 +/- 0.06). Upon oestrus synchronization, the Beta group received 50 mg of beta-carotene per day during 35 days pre- and 17 days post-ovulation. The day 4, 8, 12 and 16 post-ovulation, blood samples were collected for quantification of serum P4 concentrations by radioimmmunoassay, and transrectal ultrasonographic scanning was performed at day 18 for evaluating CLT and VLT. Overall, CLT and VLT mean were 3.10 and 2211.1 mm(3) respectively. The Beta-goats depicted both the largest values for CLT (p = 0.07) and serum P4 levels (p = 0.05), with no differences (p = 0.53) for VLT between treatments. Results suggest a higher efficiency within the cellular-enzymatic groups defining the steroidogenic pathways in the beta-carotene-supplemented goats, generating a larger P4 synthesis. The last is essential for ovulation of healthy oocytes, maintenance of uterine quiescence, nourishment and survival of the embryo around implantation; all of them of paramount significance during the maternal recognition of pregnancy process.

Effects of body condition and protein supplementation on LH secretion and luteal function in sheep

In ruminants, nutrition is one of the exogenous inputs affecting reproductive function at different levels of the hypothalamic-hypophyseal-gonadal axis. However, the exact mechanisms or even the identification of the signalling metabolic compounds by which nutrition affects reproductive function still need further clarification. The role of static body condition (BC) and its interaction with a short-term protein supplementation (PL), on secretion of metabolic hormones [growth hormone (GH), insulin and insulin-like growth factor-1 (IGF-1)], as well as on secretion of LH and progesterone (P4) was evaluated in sheep. Twenty-four Rambouillet ewes divided into two groups, with lower (LBC) and higher body condition (HBC), were randomly assigned within BC to one of two PL levels: low (LPL, 24% of crude protein; 14 g/animal/day), and high (HPL, 44% of crude protein; 30 g/animal/day). The secretion of GH, insulin, IGF-1 and LH was evaluated on day 10 of the oestrous cycle; appearance and timing of oestrous behaviour were previously detected using rams. Progesterone secretion was evaluated on day 13 of the same cycle. No differences were found (p > 0.05) between PL groups on serum GH concentrations during the sampling period (overall mean of 4.0 +/- 0.3 ng/ml), but a trend for lower values in HBC sheep was found (3.6 +/- 0.4 vs 4.4 +/- 0.4 ng/ml, p = 0.06). A BC effect was observed (p < 0.05) on serum IGF-1 level, with higher values in HBC sheep (p < 0.05). Neither BC nor PL affected (p > 0.05) secretion of LH and the number of corpora lutea, nor serum P4 and insulin concentrations. Results indicate a predominance of the static component of nutrition on sheep metabolic hormone responses, GH and IGF-1, with no effect of short-term PL on secretion of pituitary and ovarian hormones as well as luteal number and activity.

Body condition and protein supplementation positively affect periovulatory ovarian activity by non LH-mediated pathways in goats

Effects of rumen undegradable intake protein (UIP) supplementation on ovarian activity and serum insulin, GH, and LH were evaluated in goats having low or high body condition (BC). Goats with either low BC (n=16, 28.7+/-0.8 kg BW, BC=2.1+/-0.3) or high BC (n=16, 38.4+/-0.8 kg, BC=3.2+/-0.3) received, during 40-days, one of the two protein supplementation levels: without UIP or with UIP (120 g goat(-1)d(-1)). Oestrus was synchronized with two i.m. doses of PGF(2alpha), and jugular blood samples were collected from 36 to 42 h after the second prostaglandin injection at 15 min intervals. Serum concentrations of insulin, LH, and GH were measured The number of preovulatory follicles and the number of corpora lutea (CL) were evaluated by transrectal ultrasonography at 1 and 4 days after the second prostaglandin dose, respectively. Does with higher BC had more CL than those in the lower condition group (2.8+/-0.2 versus 1.8+/-0.2, P<0.05). Similarly, goats receiving UIP supplementation had more follicles (2.6+/-0.2 versus 1.9+/-0.2, P<0.05) and tended to have more CL (2.6+/-0.2 versus 2.0+/-0.2, P=0.05) than does not receiving UIP. Neither BCS nor UIP supplementation affected serum GH or LH concentrations, pulsatility, or area under the curve. High BC does produced more insulin (1.92+/-0.17 versus 0.81+/-0.17 ng/mL, P<0.01 ng/mL) than lower BC goats; the same for UIP-supplemented (1.69+/-0.18 versus 1.04+/-0.18, P<0.05). Results suggest that the increased ovarian activity observed in both UIP-supplemented and higher BC goats was not the result of changes in LH or GH, suggesting effects at a local level, through changes in insulin in a non-GnRH-gonadotrophin dependent manner.

Interactions between metabolic status, pre-breeding protein supplementation, uterine pH, and embrionic mortality in ewes: preliminary observations

The effect of prebreeding short-term protein supplementation level (PL) and body condition (BC) on fertility rate (FERT,%), uterine pH and embryonic mortality (EMORT,%) in sheep, was evaluated. Multiparous Rambouillet ewes at low BC (LC; n = 6, 62.7+/-1.7 kg) or high BC (HC; n = 6, 71.9 +/-1.7 kg), received, within BC, one of two levels of ruminally undegradable protein: low (LP, 14 g/ewe per day) and high (HP, 30 g/ewe per day). Once the animals were euthanized, corpus luteum number (CLN), as an indicator of ovulation rate, was registered and uterine horns were irrigated to recover embryonic tissue plus associated membranes as well as to measure uterine pH (UpH). While EMORT- 1 considered a nonadjusted relationship between the number of embryos and CLN, EMORT-2 considered an analysis of covariance using CLN as the covariate. The HP-supplemented ewes had the lowest FERT (p = 0.06; 100% vs 50%) and the highest EMORT (EMORT-1, 16.6% vs 53.8%, p = 0.08; EMORT-2, 52.0% vs 14.5%, p = 0.07) when compared to the LP-supplemented ewes. Neither BC nor PL affected CLN, CL weight or P4 release (p > 0.10). While the lowest UpH (p = 0.04) was observed in the HP-supplemented ewes, this group also showed the lowest fertility and the highest embryonic mortality.