Utilising male stimulus to improve the reproductive efficiency of 8-month-old nulliparous ewes and adult parous ewes

We tested whether utilising the male effect to stimulate ewes before the mating period can reduce the time to conception following the introduction of entire rams, and increase fertility, prolificacy, and reproductive rate (number of fetuses per 100 ewes exposed to fertile rams). A retrospective analysis was used to analyse records from 59,716 ewes collected over 34 years (1986-2020) from seven genotypes: Border Leicester, Composite (crossbred), Dorset, Merino, Dorset x Polypay, Rambouillet, White Suffolk. The dataset also included nulliparous young ewes (mated at age 8 months) and adult parous ewes. Vasectomized rams were used to stimulate 20,632 ewes before a mating period that lasted 2 or 3 estrous cycles, and the outcomes were compared with those from 39,084 ewes that had not been stimulated. Independently of genotype, utilising the male stimulus advanced the average conception date by 8 days for young ewes (P < 0.0001) and by 1 day for adult ewes (P < 0.0001). The male stimulus also increased the proportion of ewes that conceived in their first cycle by 33 % for young ewes and by 6 % for adult ewes (P < 0.0001). For the cycle of conception, there were significant (P < 0.0001) effects of two interactions: male stimulus x age at mating and male stimulus x live weight at mating. The male stimulus improved fertility in both adult ewes (99.8 % vs 89 %; P < 0.001) and young ewes (77.7 % vs 81.3 %; P < 0.001). The male stimulus increased the number of young ewes (41.9 % vs 11.1 %; P < 0.001) and adult ewes (16.6 % vs 2.7 %; P < 0.001) that conceived multiple fetuses in the first 17 days of the mating period. The reproductive rate was improved by the male stimulus in young ewes (129 % vs 135 %; P < 0.001) but not in adult ewes (120 % vs 122 %; P = 0.12). When all animals for all breeds were included in the analyses, there were improvements in fertility, prolificacy, and reproductive rate as age and live weight increased at mating (P < 0.0001). We conclude that, independently of genotype, utilising the male stimulus before the mating period reduces the time to conception and improves reproductive performance in both young and adult ewes.

Perspective: science and the future of livestock industries

Since the 1990s, livestock industries have been forced to respond to major pressures from society, particularly with respect to methane emissions and animal welfare. These challenges are exacerbated by the inevitability of global heating and the effects it will have on livestock productivity. The same challenges also led to questions about the value of animal-sourced foods for feeding the world. The industries and the research communities supporting them are meeting those challenges. For example, we can now envisage solutions to the ruminant methane problem and those solutions will also improve the efficiency of meat and milk production. Animal welfare is a complex mix of health, nutrition and management. With respect to health, the 'One Health' concept is offering better perspectives, and major diseases, such as helminth infection, compounded by resistance against medication, are being resolved through genetic selection. With respect to nutrition and stress, 'fetal programming' and the epigenetic mechanisms involved offer novel possibilities for improving productivity. Stress needs to be minimized, including stress caused by extreme weather events, and solutions are emerging through technology that reveals when animals are stressed, and through an understanding of the genes that control susceptibility to stress. Indeed, discoveries in the molecular biology of physiological processes will greatly accelerate genetic progress by contributing to genomic solutions. Overall, the global context is clear - animal-sourced food is an important contributor to the future of humanity, but the responses of livestock industries must involve local actions that are relevant to geographical and socio-economic constraints.

Frontiers in sheep reproduction - making use of natural responses to environmental challenges to manage productivity

This review addresses advances, directions and opportunities for research on sheep reproduction in the context of the global challenges of food security and climate change, and demand for 'clean, green and ethical' (CGE) animal management. The foundation of CGE management is an understanding of the physiological processes through which the reproductive system responds to changes in the animal's environment. These days, to the main environmental factors (photoperiod, nutrition, pheromones), we need to add stress from extreme weather events. With respect to nutrition in rams, we now have a deeper understanding of the responses of the brain centres that control gonadotrophin secretion (the kisspeptin system). At testis level, we have found that nutrition affects non-coding RNAs in Sertoli cells and germ cells, thus affecting the balance between cell proliferation and apoptosis. This proliferation-apoptosis balance is also affected during prenatal development, when undernutrition or stress in pregnant ewes seems to elicit epigenetic changes in developing gonads that could affect offspring fertility in adult life. With respect to nutrition in ewes, metabolic signals act directly on ovarian follicles, and thus change ovulation rate, but the variety of signals now includes the adipokines. An early concern was that nutritional supplements that increase ovulation rate would also increase embryo mortality but we now know that embryo survival is improved under field conditions. Finally, we had always thought that the efficiency gains from early puberty in lambs could only be achieved by accelerating fat accumulation, but we now know that faster muscle growth will achieve the same goal, offering two advantages in meat production systems. With respect to pheromones ('ram effect'), we have a deeper understanding of the brain responses (kisspeptin system) but, most importantly, a realization that the response of ewes to the ram signal involves cell division in memory centres. Many opportunities remain.

A Brief Update on the Challenges and Prospects for Goat Production in Mexico

In Mexico, information on goat production is scarce and documenting goat production challenges and future perspectives could be of great value, not only for Latin America, but also for international players—including those from farms, industry, and academia. Therefore, the objective of this review is to provide current knowledge on goat production systems in Mexico and discuss current challenges and future perspectives for this animal production sector. In Mexico, more than 70% of goats are produced under extensive production systems in arid and semi-arid areas and roughly 25% are produced in intensive or semi-intensive systems. Main breeds are French Alpine, Saanen, Toggenburg, LaMancha, Nubian, Boer, and their crosses. The main challenges are correlated at different levels, where economic, social, and environmental issues are mixed and are closely associated with goat health and welfare. Newly available farming technologies could be an option that should be explored. Mexican goat farming systems will need to look at the animal, social, and environmental factors to promote sustainable production systems.

Interactions between Nutrition and the “Ram Effect” in the Control of Ovarian Function in the Merino Ewe

Simple Summary

Clean, green, and ethical management of sheep flocks involves the use of socio-sexual stimuli (the “ram effect”) to coordinate nutritional inputs into reproductive success. However, the value of the “ram effect” is limited by three factors: (i) the proportion of the ewe flock that ovulates; (ii) ovulation rate in ewes that respond to the ram stimulus; and (iii) luteal failure after the first ram-induced ovulation, leading to short luteal phases. We tested whether these problems could be overcome by using a brief nutritional supplement (500 g lupin grain per head daily for 6 days) to stimulate ovarian activity. Lupin supplementation before ram introduction did not improve the percentage of the ewe flock that ovulates or reduce the frequency of short cycles (so will not improve the synchrony of lambing). However, lupin supplementation after ram introduction should be used to increase prolificacy.

Abstract

We tested whether short-term nutritional supplementation (500 g lupin grain per head daily) would affect the response of ewes to the ram effect. Experiment 1 (end of non-breeding season): ewes were supplemented for either Days −6 to −1 relative to ram introduction (n = 24) or for 12 days after ram introduction (Days 11 to 22 of the ram-induced cycle; n = 29). Controls (n = 30) were not supplemented. Across all groups, 94–100% of ewes ovulated. Supplementation before ram introduction did not affect ovulation rate at the ram-induced ovulation but increased it during the ram-induced cycle (Control 1.37; supplemented 1.66; p < 0.05). Experiment 2 (the middle of non-breeding season): the supplement was fed for Days −5 to −1 relative to ram introduction. Again, supplementation did not increase number ovulating (Control 16/29; Supplemented 10/29) but it did increase ovulation rate at the ram-induced ovulation (Control 1.31; Supplemented 1.68; p < 0.05). In neither experiment did supplementation affect the frequency of short cycles. Supplementation before ram introduction did not improve the percentage of ewes ovulating or reduce the frequency of short cycles (so will not improve the synchrony of lambing). However, supplementation after ram introduction can increase prolificacy.

Recent Insights Into Processing Approaches and Potential Health Benefits of Goat Milk and Its Products: A Review

Goat milk is considered to be a potential source of various macro- and micro-nutrients. It contains a good proportion of protein, fat, carbohydrates, and other nutritional components which help in promoting nutritional and desirable health benefits. Goat milk is considered to be superior in terms of numerous health benefits, and lower risk of allergy, when compared to the milk of other species. Several processing techniques such as pasteurization, ultrafiltration, microfiltration, and ultrasound have been employed to enhance the quality and shelf life of goat milk and its products. The diverse range of goat milk-based products such as yogurt, cheese, fermented milk, goat milk powder, and others are available in the market and are prepared by the intervention of advanced processing technologies. Goats raised in pasture-based feeding systems are shown to have a better milk nutritional composition than its counterpart. Goat milk contains potential bioactive components, which aids in the maintenance of the proper metabolism and functioning of the human body. This review gives insight into the key nutritional ingredients and bioactive constituents present in goat milk and their potential role in the development of various functional foods using different processing technologies. Goat milk could be considered as a significant option for milk consumption in infants, as compared to other milk available.

Nanotechnology and Reproductive Management of Farm Animals: Challenges and Advances

Reproductive efficiency of farm animals has central consequences on productivity and profitability of livestock farming systems. Optimal reproductive management is based on applying different strategies, including biological, hormonal, nutritional strategies, as well as reproductive disease control. These strategies should not only guarantee sufficient reproductive outcomes but should also comply with practical and ethical aspects. For example, the efficiency of the biological- and hormonal-based reproductive strategies is mainly related to several biological factors and physiological status of animals, and of nutritional strategies, additional factors, such as digestion and absorption, can contribute. In addition, the management of reproductive-related diseases is challenged by the concerns regarding the intensive use of antibiotics and the development of antimicrobial resistant strains. The emergence of nanotechnology applications in livestock farming systems may present innovative and new solutions for overcoming reproductive management challenges. Many drugs (hormones and antibiotics), biological molecules, and nutrients can acquire novel physicochemical properties using nanotechnology; the main ones are improved bioavailability, higher cellular uptake, controlled sustained release, and lower toxicity compared with ordinary forms. In this review, we illustrate advances in the most common reproductive management strategies by applying nanotechnology, considering the current challenges of each strategy.

Towards objective measurement of reproductive performance of traditionally managed goat flocks in the drylands of Ethiopia

Reproductive performance is a key determinant for the efficiency of goat production. Regular monitoring of reproductive efficiency is essential to assess management and to avoid financial losses due to poor performance. To allow more objective measurement and comparisons over time, we propose a novel quantitative approach for defining annual reproductive performance by combining common performance indicators into a goat flock index. Commonly used reproductive performance measures were collected from 242 goat flocks in four districts in dryland of Ethiopia between July 2018 and February 2019. Principal component analysis (PCA) was performed to identify biologically meaningful latent components that explain annual reproductive output (ARO) and annual reproductive wastage (ARW). Together with the remaining annual reproductive performance measures, the ARO and ARW components were included in a PCA to derive an algorithm for a goat annual reproductive performance index (G-ARPI). One component representing variation in kidding interval, PC_ARO1 and PC_ARW1 was extracted and normalized to a 10-scale value. The flocks were classified into good performing (15.63%) with index > 8.5, moderately performing (48.21%) with index values ranging from 6.5 to 8.5 and poor performing (36.16%) with index < 6.5. Good performing flocks have higher scores for reproductive output measures, lower scores for reproductive wastage and lower kidding interval. The proposed G-ARPI can be used as an objective tool to compare reproductive performance between management systems, evaluate the costs of poor reproductive management and will be useful for economic models that aim to identify the most cost-efficient intervention option and monitor the impact of interventions. We present here the index for goat production in dryland systems in Ethiopia; the approach can easily be adapted to other production systems elsewhere.

'Rotatinuous' stocking as a climate-smart grazing management strategy for sheep production

We aimed to evaluate the effect of different grazing management strategies on carcass characteristics traits, meat quality and CH₄ intensity and yield of lambs grazing Italian ryegrass pastures in Southern Brazil. A grazing trial was performed (2014 and 2015) in a randomized complete block design with two grazing management targets and four replicates. Treatments were traditional rotational stocking (RT), with pre- and post-grazing sward heights of 25 and 5 cm, respectively, and 'Rotatinuous' stocking (RN), with pre- and post-grazing sward heights of 18 and 11 cm, respectively. Castrated crossbred Texel and Polwarth lambs were used. Results indicated that diet cost per kg of dry matter (p = 0.001) and per hectare (p < 0.001) were lower for RN than for RT treatment. Final live weight (p = 0.022) and hot and cold carcass weight (p = 0.006) were greater for the RN treatment. All commercial cuts were greater for RN than for RT treatment. The RN treatment presented greater (p < 0.001) production of carcass, edible food and crude protein. Feed efficiency and feed cost conversion were better for RN than for RT treatment. CH₄ intensity per kg of carcass, edible food and crude protein gain were 2.6, 2.7 and 2.1 times lower (p < 0.001) for RN. Moreover, CH₄ yield was lower (p = 0.014) for RN than for RT treatment, with an average of 7.6 and 8.3% of the gross energy intake, respectively. We conclude that the 'Rotatinuous' stocking results in a greater carcass production, carcass quality and lower diet cost, and CH₄ intensity and yield of grazing lambs. Adopting this grazing management strategy could enhance both lamb production and mitigation of CH₄ intensity and yield in grazing ecosystems, which could be considered a good example of climate-smart livestock production.

Nutritional supplementation improves the sexual response of bucks exposed to long days in semi-extensive management and their ability to stimulate reproduction in goats

In confined management systems, well-nourished bucks rendered sexually active by exposure to long days are efficient in fertilizing out-of-season goats. However, underfeeding is common in semi-extensive management systems and may reduce the reproductive efficiency of bucks. The objective of the present study was to determine whether nutritional supplementation improved the sexual activity of bucks submitted to long days in semi-extensive management systems and their ability to stimulate the reproduction of goats in semi-extensive or confined conditions. In experiment 1, three groups of bucks were placed in different flocks and grazed daily with females for 7 h. Each day after grazing, males were separated from females and moved into open pens. One group did not receive any treatment (control group; n = 6). Two other groups were submitted to artificially long days from 15 November to 15 January. From 16 January, one group did not receive nutritional supplementation (long-day group; n = 5), whereas bucks from the other group each received 600 g of a commercial concentrate (long-day+supplementation group; n = 5). The fourth group was kept in confined conditions, exposed to long days and fed alfalfa hay (long-day confined group; n = 6). On 26 March, anovulatory goats from other flocks were assigned to four groups (n = 27 each) and confined separately in open pens. Three bucks of each group were housed with the females. Pregnancy rates were greater in the goats housed with the long-day group than those housed with the control group (P < 0.01). However, pregnancy rates did not differ between the long-day confined group (89%) and long-day+supplementation group (70%; P = 0.09), but these rates were greater than those from the long-day (37%) and control groups (0%; P < 0.05). In experiment 2, two groups of males (n = 3 each) were incorporated into two flocks under semi-extensive management and grazed daily with females for 7 h. One group of males did not receive any treatment (control group). The other group was submitted to long days and nutritional supplementation as in experiment 1 (long-day+supplementation group). Males remained with females during the whole study. The pregnancy rate was greater in the goats joined by males of the long-day+supplementation group (78%) than in those from the control group (0%; P < 0.001). We conclude that long days and nutritional supplementation improve the ability of bucks kept in semi-extensive management to stimulate reproduction of out-of-season goats in confined or semi-extensive management systems.

Reproductive performance of goats treated with free gonadorelin or nanoconjugated gonadorelin at estrus

The reproductive performance of goats that received a GnRH analog (gonadorelin) fabricated with or without chitosan-sodium tripolyphosphate (TPP) nanoparticles on the day of estrus (day 0) was evaluated. The chitosan-TPP polymer was conjugated with gonadorelin using an ionic gelation method. Thirty-three multiparous Zaraiebi goats were synchronized for estrus with 2 intramuscular (im) injections of 125 μg prostaglandin F_2α 14 d apart. Goats showing signs of estrus were divided equally into 3 experimental groups and received a single im injection of 1 mL physiological saline (placebo; control), 50 μg/mL gonadorelin (GnRH), or 12.5 μg (quarter of GnRH dose)/mL chitosan-TPP-conjugated gonadorelin nanoparticles (NGnRH). Each goat underwent ultrasound imaging of their ovaries at day 0 and at day 10 after mating, and pregnancy was diagnosed 28 and 45 d after mating. The concentrations of estradiol (E₂) and progesterone (P₄) were determined at day 0 and at days 7, 14, 21, and 42 after mating. NGnRH size, polydispersity, and zeta potential were 93.91 nm, 0.302, and 11.6 mV, respectively. Chitosan-TPP nanoparticles showed 91.2% entrapment efficiency for GnRH. No differences in estrus rate, interval to estrus, or ovarian structure at day 0 were observed among the experimental groups, but the GnRH and NGnRH treatments significantly decreased the duration of estrus compared with the control. At day 10 after mating, both GnRH and NGnRH increased (P = 0.011) the number of corpora lutea compared with the control. Treatment with GnRH increased (P = 0.023) serum E₂ concentrations from day 7 to 42 after mating compared with NGnRH and control treatments. The highest (P = 0.043) serum P₄ concentration was observed in the GnRH group, followed by the NGnRH and control groups. The increase in serum P₄ concentration started earlier a on day 7 in the GnRH group but later on day 14 in the NGnRH group. Compared with the control, GnRH resulted in a higher (P = 0.041) P₄-to-E₂ ratio, followed by NGnRH. Both gonadorelin treatments significantly increased the twinning rate, the number of embryos at days 28 and 42, and prolificacy and decreased pregnancy losses compared with the control. In conclusion, the administration of GnRH at the time of estrus improved the prolificacy of goats by increasing both the ovulation rate and the number of embryos. In addition, the nanoformulation developed in this study allowed a 75% reduction in the conventional dose of gonadorelin without affecting the fertility and prolificacy of goats, indicating the bioavailability of the reduced GnRH dose after conjugation with developed nanoformula.

Male effect using photostimulated bucks and nutritional supplementation advance puberty in goats under semi-extensive management

Well-nourished spring-born female goats reach puberty in the autumn of the same year. Contrastingly, undernourished spring-born females reach puberty in the autumn of the following year. Therefore, in this study, we reared female goats (undernourished) under semi-extensive management and determined whether the introduction of photostimulated, sexually active males, advances puberty in these females, and whether nutritional supplementation increases the proportion of kidding females. Goats were born on March 30 and weaned at 2 months of age. Then, they grazed natural vegetation from 10:00 to 18:00 each day. Starting in December, two groups did not receive feed supplementation after grazing, whereas two other groups received 600 g daily supplements of a commercial concentrate. In April, one non-supplemented (n = 10) and other supplemented groups (n = 11) were moved indoors and kept in separate pens, where they were joined with sexually active bucks (n = 1 per group). Males were rotated daily between groups for 7 days. Other non-supplemented (n = 8) and supplemented groups (n = 11) were not joined with males. Most of the female goats under study reached puberty (70-100%). However, in supplemented and non-supplemented groups joined with males, puberty commenced much earlier (April) than in those non-exposed to males (September) (P < 0.001). The proportion of pregnant goats did not differ between groups joined with males (P > 0.05), but the proportion of goats that kidded was higher in supplemented (7/11) than in non-supplemented goats (2/10) (P < 0.05). In conclusion, in spring-born goats, the male effect using sexually active males advanced puberty, and nutritional supplementation increased the proportion of kidding goats in females reared under semi-extensive management.

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

The purpose of this study was to determine goat milk physicochemical parameters during the feed scarcity season. An evaluation was made for 398 milk samples from 80 multiparous goats belonging to three different production systems: (S1) mechanized milking grazing pasture and harvested residue (alfalfa) and grain supplemented; (S2) system grazing native pasture; and (S3) system grazing native pasture and grain supplemented. The general averages were: fat (FT) 4.0 ± 0.20%, protein (PR) 3.3 ± 0.05%, lactose (LC) 4.9 ± 0.09%, nonfat solids (NFS) 8.9 ± 0.13%, total solids (TS) 14.5 ± 0.20%, temperature (TM) 24.6 ± 1.06°C, and acidity (pH) 6.7 ± 0.049. Most of the physicochemical components of milk were affected (p < 0.0001) by the production system × month interaction and production system × group × month interaction. The FT content was higher (p < 0.05) in S2 (4.56 ± 0.18) than in S1 (3.64 ± 0.20) and S3 (3.50 ± 0.20). LC differed (p < 0.05) in S2 (5.07 ± 0.08) than in S1 (4.77 ± 0.09) and S3 (4.70 ± 0.09). No differences were observed for the rest of the variables (p < 0.05) among the production systems. The study unveiled a higher content of FT, LC, NFS, PR, and TS for S2 than for S1 and S3. This higher content may be explained because S2 only grazed on herbs and shrubs, in contrast to S1 and S3 which were additionally supplemented with grain concentrates.

Subtropical goats ovulate in response to the male effect after a prolonged treatment of artificial long days to stimulate their milk yield

The objectives of this study were to determine (i) if in subtropical goats that gave birth during mid-December, the exposition to an artificial long-day photoperiod consisting in only 14 hr of light per day can increase the milk yield and (ii) to test whether these females can respond to the male effect at the end of the prolonged photoperiodic treatment. In experiment 1, 17 lactating goats were maintained under natural short days (control group), while another 22 goats were maintained under artificial long days (treated group) consisting in 14 hr light and 10 hr darkness starting at day 10 of lactation. The continuous exposition to an artificial long-day photoperiod produced an increase in the milk yield level during the first 110 days of lactation (time × treatment interaction; p = .01), while none of the milk components were modified due to the photoperiodic treatment (p > .05). In experiment 2, all control and treated anovulatory goats were submitted to the male effect using photostimulated males. All females showed oestrous behaviour within the first 10 days that were in contact with males (100% in both groups; p > .05). Thus, the latency to onset of oestrus did not differ between females from control (58.2 ± 3.0 hr) and treated (62 ± 4.6 hr) groups. Male exposition provoked ovulation independently if females were previously under long days or natural photoperiod (96 vs 100%, respectively; p = .79). It was concluded that exposure to 14 hr of light per day in subtropical goats that gave birth in late autumn stimulates milk yield without preventing the ovulation in response to the male effect at the end of the prolonged photoperiodic treatment.

Proficiency Testing of Feed Constituents: A Comparative Evaluation of European and Developing Country Laboratories and Its Implications for Animal Production

Proficiency tests, with two feed samples each year, for various constituents (proximate, macro- and microminerals, feed additives, and amino acids) were conducted in 2014 and 2015. A total of 40 and 50 European and 73 and 63 developing country feed analysis laboratories participated in the study in 2014 and 2015, respectively. The data obtained from these two sets of laboratories in each year enabled a comparison of the performance of the European and developing country laboratories. Higher standard deviation and several-fold higher coefficients of variation were obtained for the developing country laboratories. The coefficients of variation for chemical composition parameters, macrominerals, microminerals, and amino acids were higher by up to 9-fold, 14-fold, 10-fold, and 14-fold, respectively, for the developing country laboratories compared with the European laboratories in 2014, while the corresponding values for 2015 were 4.6-fold, 4.4-fold, 9-fold, and 14-fold higher for developing county laboratories. Also, higher numbers of outliers were observed for developing countries (2014, 7.6-8.7% vs 2.9-3.0%; 2015, 7.7-9.5% vs 4.2-7.0%). The results suggest higher need for developing country feed analysis laboratories to improve the quality of data being generated. The likely impact of higher variability of the data generated in developing countries toward safe and quality preparation of animal diets, their impact on animal productivity, and possible ways to improve the quality of data from developing countries are discussed.