Seasonal changes in oestrus activity and ovulation rate in Rasa Aragonesa ewes maintained at two different body condition levels

Differential effect of melatonin on ram spermatozoa depending on the allelic variant of the RsaI polymorphism of the MTR1A gene, incubation medium and season

Context The Rsa I polymorphism of the melatonin receptor MTNR1A gene affects seasonal reproduction in sheep, but its effect on ram spermatozoa and their response to melatonin is unknown. Aims This study aims to evaluate whether Rsa I polymorphism of the MTNR1A gene influences the response of ram spermatozoa to in vitro added melatonin. Methods Spermatozoa from rams carrying different Rsa I allelic variants were incubated with melatonin in a TALP medium or a capacitation-triggering medium during the reproductive and non-reproductive seasons. After incubation, sperm motility, membrane integrity, mitochondria activity, oxidative damage, apoptotic markers and capacitation status were assessed. Key results In the reproductive season, the T/T genotype was related to some adverse effects of melatonin when spermatozoa were incubated in TALP medium, whereas the C/C genotype was linked with adverse effects when the hormone was added in a capacitation-triggering medium. The decapacitating effect of melatonin on spermatozoa was also different depending on genotype. Conclusions The melatonin effect on spermatozoa from rams carrying different Rsa I genotypes differed depending on the season and the medium. Implications The knowledge of the Rsa I allelic variant of the MTNR1A gene of rams could be helpful when carrying out in vitro reproductive techniques in the ovine species.

Genotyping of rams based on melatonin receptor 1A gene polymorphisms: a tool in sire selection?

Context Several polymorphisms in the melatonin receptor 1A gene (MTNR1A ) have been related to reproductive performance in ovine. Aims To investigate the effect of the Rsa I and Mnl I polymorphisms on ram seminal quality. Methods Eighteen Rasa Aragonesa rams were genotyped for the Rsa I (C/C, C/T, T/T) and Mnl I (G/G, G/A, A/A) allelic variants of the MTNR1A gene. Individual ejaculates were analysed once a month throughout the whole year. Sperm motility, morphology, membrane integrity, levels of reactive oxygen species (ROS), phosphatidylserine (PS) inversion, DNA fragmentation and capacitation status were assessed. The effect of the season and polymorphisms on seminal quality was evaluated by mixed ANOVA. Key results Both polymorphisms had an effect on membrane integrity and viable spermatozoa with low levels of ROS and without PS translocation, and Rsa I also on motile and DNA-intact spermatozoa. An interaction between both polymorphisms was found, pointing to a negative effect on seminal quality of carrying the T or A allele in homozygosity. Differences were higher in the reproductive than in the non-reproductive season. Conclusions Mutations substituting C by T and G by A at Rsa I and Mnl I polymorphic sites, respectively, in the MTNR1A gene in rams could decrease the seminal quality. Implications Genotyping of rams based on melatonin receptor 1A could be a powerful tool in sire selection.

Genome-wide analysis reveals that the cytochrome P450 family 7 subfamily B member 1 gene is implicated in growth traits in Rasa Aragonesa ewes

Sheep are very well adapted to changing environments and are able to produce and reproduce with low inputs in feed and water better than other domestic ruminants. Indeed, the ewe body condition score (BCS) and live weight (LW) play a significant role in productive and reproductive performance. This work conducts a genome-wide association study (GWAS) to detect genetic variants associated with growth traits in 225 adult ewes of the Rasa Aragonesa breed by using the genotypes from 50 k and HD Illumina Ovine BeadChip. These ewes were measured for LW, BCS and growth rate (GR) for 2 years, from January to September. Corrected phenotypes for BCS, LW and GR were estimated and used as input for the GWAS. Only one single nucleotide polymorphism (SNP) rs425509273 in chromosome 9 (OAR9), associated with the GR, overcame the genome-wise significance level. One, three and nine SNPs were associated at the chromosome-wise level (FDR 10%) for traits BCS, LW and GR, respectively. The cytochrome P450 family 7 subfamily B member 1 (CYP7B1) candidate gene, located 83 kb upstream from SNP rs425509273 in OAR9, was partially isolated and Sanger-sequenced. Fifteen polymorphisms comprising 12 SNPs, two indels and one polyC, were detected in promoter, exon 1, 3, 5, and intron 1-3 region. The SNP association analysis of the polymorphisms located close to the transcription start site (TSS) showed that a 22 bp insertion located at -58 nucleotides from the TSS (indel (-58)), a polyC (-25), and two A/G SNPs (SNP3 (-114) and SNP5 (-63)) were associated with the GR trait, whereas only the indel (-58) was associated with the BCS trait. The haplotype analysis confirmed these results. The functional characterisation of the polymorphisms at CYP7B1 gene in liver by real-time quantitative PCR analysis confirmed that the mutations in the promoter region affected CYP7B1 gene expression. Our results demonstrated the involvement of the CYP7B1 gene promoter on GR and BCS traits in Rasa Aragonesa. These findings suggest that variations in ovine CYP7B1 may serve as potential genetic markers to be used in breeding programmes to improve growth characteristics that could influence reproductive traits.

Early Dalmatian farmers specialized in sheep husbandry

The spread of farming in the central and western Mediterranean took place rapidly, linked to the Impressa Ware. The Impressa Ware originated somewhere in the southern Adriatic and spread westwards across the Mediterranean. These early farmers had an economy based on cereal agriculture and caprine husbandry, but there is still little information on how this agropastoral system functioned. This study aims to unravel the farming practices of the early Dalmatian farmers linked to the Impressa culture by using an integrated analysis, combining archaeozoology, palaeoproteomics and stable isotopes, applied to the faunal assemblages of Tinj-Podlivade and Crno Vrilo. The results show: (1) the composition of the flocks was overwhelmingly sheep; (2) sheep exploitation at both sites was similar, focusing on milk and meat; (3) sheep reproduction was concentrated at the beginning of winter, with no reproduction in autumn as in later sites in the western Mediterranean. We conclude that a common animal economy existed at both sites, which could be related to the mobility practiced by these early farming societies throughout the Mediterranean.

Exposure of rams in sexual rest to sexually activated males in spring increases plasma LH and testosterone concentrations

Eight stimulating rams, and twelve stimulated rams, were used to determine whether a similar endocrine response to the introduction of sexually active males in spring in a flock of ewes is observed in a flock of rams. The stimulating rams (n = 4) were induced into a sexually active state by exposure to 2 months of long days (16 h light/d) (15 December-15 February). At the end of the long-day period, rams were returned to the natural photoperiod. Control-stimulating rams (n = 4) were kept under the natural photoperiod. On April 20, stimulated rams were divided into 2 groups, and joined with activated (ACT; n = 6) or control stimulating rams (C; n = 6). On the day of ram introduction, stimulated rams were blood sampled for 8 h at 20-min intervals, from 4 h before to 4 h after ram introduction, and next day from 24 to 28 h after ram introduction, and analyzed for plasma LH concentrations, and 10, 20 and 30 days after ram introduction to measure plasma testosterone levels. Mean (±SEM) plasma LH concentrations (ng/ml) of stimulated rams were similar during the 4 h before stimulating-ram introduction (ACT: 0.59 ± 0.03; C: 0.53 ± 0.04; P > 0.05). The introduction of the photoperiod-treated stimulating rams increased LH concentrations of stimulated rams during the 4 h after their introduction (1.14 ± 0.37) compared with the C group (0.51 ± 0.03; P < 0.05), especially during the first hour (ACT: 0.93 ± 0.16; C: 0.49 ± 0.03; P < 0.05), and during the blood sampling period 24-28 h after ram introduction (0.75 ± 0.07 vs. 0.58 ± 0.04; P < 0.05). Before the introduction of stimulating rams, the LH pulse frequencies and amplitudes did not differ between groups; however, LH pulsatility was higher at 4 h (0.58 ± 0.11 pulses/h; P < 0.05), and had trend to be higher 24 h (0.50 ± 0.06) (P = 0.10) after the introduction of the photoperiod-treated stimulating rams compared with the control-stimulating rams (0.29 ± 0.08 and 0.29 ± 0.10, respectively). As for LH pulses, there was an effect of group (P < 0.05) on LH amplitude, which presented a trend to be higher in ACT rams 4 h after ram introduction (1.68 ± 0.30; P < 0.10) and higher 24 h (1.07 ± 0.08; P < 0.05) after ram introduction, compared with LH amplitudes of C rams (0.71 ± 0.06 and 0.82 ± 0.07, respectively). Plasma testosterone concentrations of rams exposed to photoperiod-treated activated rams were higher than those of rams exposed to control-stimulating rams, at 4 h, 20 and 30 days after ram introduction (P < 0.05). In conclusion, sexually active rams in spring are able to stimulate LH and testosterone secretion of other rams in sexual rest, a phenomenon we called "ram-to-ram effect".

High body condition score combined with a reduced lambing to ram introduction interval improves the short-term ovarian response of milking Lacaune ewes to the male effect

The male effect is an effective natural technique to induce off-season ovulation and ultimately mating or artificial insemination in small ruminants. It constitutes an alternative to hormonal treatments in conventional breeding systems and, to shift and organise the yearly production cycle, is currently the only solution complying with European organic standards. However, its associated performances are still heterogeneous, both in terms of the global response and the extent of reproductive synchronisation of the females, due to complex interactions with environmental factors that limit its use on commercial farms. This study was carried out on a French organic farm under commercial conditions to investigate, in the field and across five consecutive years, the main parameters affecting the early ovarian response to a ram effect on Lacaune dairy ewes. While the within-year binary logistic regressions yielded contrasting results, the cross-year mixed-effect binary logistic regression models clearly showed that parameters associated with the nutritional state of the animals have a profound influence on the ovarian response of the ewes. Indeed, the probabilities of a spontaneous resumption of ovarian activity before the ram effect and of an early ovarian response to the ram effect were positively associated with the body condition score, total milk production and the age of the animals, while being negatively associated with the milk production level at the 3rd milk recording. The probabilities of a spontaneous resumption of ovarian activity before the ram effect were positively associated with the interval between lambing and the introduction of the rams. Altogether, these results indicate that the ovarian performances in response to a male effect follow a bell-curve pattern with optimal performances depending upon a complex combination between photoperiodic and nutritional cues. Regarding these latter, this study highlights the major contribution of body reserves and energy balance dynamics.

Effect of Body Condition Score, Treatment Period and Month of the Previous Lambing on the Reproductive Resumption of Melatonin-Treated Sarda Breed Sheep during Spring

Simple Summary

Improving reproductive efficiency in sheep farms is a crucial task for researchers. Therefore, the present research considers the conditions commonly found in Sarda sheep farms and evaluates the effects on reproductive activity via the following factors: exogenous melatonin treatment through subcutaneous implants, different periods of melatonin treatment, varying body condition scores (BCS) and the previous lambing of the treated ewes. The results of the present research suggest that melatonin treatment is able to reliably enhance reproductive efficiency. Furthermore, the findings indicate that optimal reproductive efficiency can be achieved by ensuring that melatonin is administered in April to ewes that have a BCS of >2.5 and have passed their third month of lactation.

Abstract

Stakeholders place great emphasis upon rationalizing the management and rearing techniques which are utilized within sheep farms. The present study aimed to investigate factors which may improve the reproductive performance of melatonin-treated Sardinian sheep via a series of three trials. The first trial (n = 100) investigated the effect of melatonin treatment alongside body condition score (BCS), the second trial (n = 150) investigated the effect of treatment alongside the date of treatment (treatment period) and the third trial (n = 150) investigated the effect of treatment alongside the previous lambing of the ewes. The findings indicated that melatonin is an effective tool for anticipating and improving the reproductive activity of in Sarda breed sheep during the springtime. Furthermore, to obtain optional results, melatonin implantation should be conducted in April, in ewes that have a BCS of >2.5 and that have passed their third month of lactation.

Semen Quality of Rasa Aragonesa Rams Carrying the FecXR Allele of the BMP15 Gene

The FecXR mutation is a variant of the ovine gene BMP15 in the Rasa Aragonesa breed. Information on the physiological importance of carrying the FecX polymorphism in rams is limited. The aim of this study was to compare semen quality, testicle characteristics, and fertility rate of rams that carry the FecXR allele. Rams (n = 15) were either FecXR allele carriers (n = 10) or non-carriers, wild type (++) (n = 5). FecXR rams exhibited higher mass motility (p < 0.05), proportion of rapid sperm (p < 0.05), and a lower proportion of slow sperm (p < 0.0001) than did ++ rams. The presence of the FecXR allele was not associated with mean scrotal circumference or testicular length and diameter, although season had a significant (p < 0.05) effect on these traits. Genotype (p < 0.05) and season (p < 0.01) had a significant effect on mean fertility rate, FecXR rams had a higher proportion of pregnant ewes than did ++ rams (p < 0.05). In conclusion, the FecXR allele produced high-quality semen throughout the year, and corresponded with an improvement in some sperm parameters, particularly, mass motility and the proportion of rapid sperm.

Commercial equine production in New Zealand. 1. Reproduction and breeding

The Thoroughbred and Standardbred studbooks are the largest in New Zealand, where the production of horses is pasture based. Each racing studbook is closed, and both have well structured systems in place for recording breeding data. There are significant pressures on the Thoroughbred and Standardbred breeding industries with declining broodmare numbers, and increasingly large book sizes for popular stallions. The breeding season for Thoroughbreds is very short, with disparity between the official breeding season and the physiologic breeding season for mares. These issues are confounded by variable gestation lengths of mares, making it difficult for mares to maintain yearly foaling patterns. However, the reproductive efficiency of Thoroughbred mares is improving, mainly due to veterinary and stud management practices such as those to ensure that dry mares are cycling at the start of the breeding season, foaling mares are bred on foal heat, and that mares are kept in good body condition at breeding. There is also a bias towards breeding younger mares with high fertility in preference to older mares, unless they have desired genetics or successful offspring. Careful management of popular Thoroughbred stallions ensures that large books of mares can be covered by natural service. In contrast, Standardbred stallions are collected every-other-day using an artificial vagina, allowing the breeding of mares at distant locations by artificial insemination, using chilled or frozen semen. Breeding horses kept at pasture under New Zealand conditions requires excellent stud management and veterinary management to achieve good outcomes.

Nutritional status affects the microRNA profile of the hypothalamus of female sheep

Recent studies on the seasonal regulation of the oestrous cycle in sheep have focussed mainly on the responses to photoperiod. However, the brain systems that control reproductive activity also respond to nutritional inputs, although the molecular mechanisms involved are not completely understood. One possibility is that small, non-coding RNAs, such as micro-RNAs (miRNAs), have significant influence. In the present study, the amounts and characteristics of miRNAs in hypothalamus from oestrous and anestrous ewes, fed low- or high-nutrient diets, were compared using Illumina HiSeq sequencing technology. In total, 398 miRNAs, including 261 novel miRNAs, were identified in ewes with an enhanced nutritional status (HEN), whereas 384 miRNAs, including 247 novel miRNAs, were identified in the ewes with a lesser nutritional status (HAN). There were eight conserved and 140 novel miRNAs expressed differentially between the two libraries. Based on quantitative real-time polymerase chain reaction, six miRNAs were assessed to verify the accuracy of the library database. Moreover, the correlation between the miRNA target and several upstream and downstream genes in the oestrus-related pathways were also verified in hypothalamus nerve cells. According to the results, nutritional status plays an important role in oestrous regulation in sheep, and the hypothalamic processes and pathways induced by nutritional signals (folic acid and tyrosine) are different from those induced by photoperiodic regulation of oestrus. We have expanded the repertoire of sheep miRNAs that could contribute to the molecular mechanisms that regulate the initiation of oestrous cycles in anestrous ewes in response to the influence of nutritional status.

Light-induced sexually active rams prevent the seasonal inhibition of luteinizing-hormone in ovariectomized estradiol-implanted ewes

The effect of the continuous presence of sexually active Rasa Aragonesa rams on the plasma luteinizing-hormone (LH) concentrations of ewes was studied from November to May. Light-treated rams were rendered sexually active (SA rams) by exposure to 2 months of artificially long days (16 h light/8 h dark) in one of two groups from either 1 November (SAR1, n = 3) or 1 December (SAR2, n = 3). Rams (n = 6) in a Control group were kept under the natural photoperiod. Thirty ewes were ovariectomized in September and implanted with a subcutaneous implant (l = 15 mm) that contained estradiol-17β. One group of ewes (SAR; n = 10) was housed with control rams from 1 October to 15 February before being housed with SAR1 rams from 16 February to 31 March, and with SAR2 rams from 1 April to 31 May. A second group of ewes (C; n = 10) remained with control rams throughout the experiment, and a third group was kept isolated from rams throughout the experiment (ISO; n = 10). Blood samples were collected weekly from November to May, and plasma LH concentrations were measured. In the breeding season (November-February), plasma LH concentrations of ewes did not differ significantly between groups (SAR: 2.00 ± 0.34; C: 1.88 ± 0.16; ISO: 1.67 ± 0.51 ng/ml). From March to May (seasonal anestrus), however, LH plasma concentrations decreased in the C and ISO groups (1.30 ± 0.20 and 0.48 ± 0.04 ng/ml, respectively), but remained at the same level as in the breeding season in the SAR group (2.30 ± 0.17 ng/ml; P < 0.001). Significant differences (P < 0.01) between groups were observed from March onwards: LH concentrations were highest in SAR ewes (P < 0.001) and lowest in the ISO ewes. In conclusion, the continuous presence of sexually active rams prevented the seasonal decrease in plasma LH concentrations, probably by preventing the seasonal negative feedback of estradiol on LH secretion.

Dietary restriction in sheep: Uterine functionality in ewes with different body reserves during early gestation

The aim of this study was to characterize insulin, leptin and IGF-1 profiles after undernutrition in pregnant ewes with different initial body condition (iBCS) and to investigate embryo quality, uterine gene expression and presence and location of proteins during early gestation (day 5). Thirty-six Rasa Aragonesa ewes were divided into 2 groups with different BCS: BCS> 2.75 (high, H, n = 19) and BCS <2.25 (low, L, n = 17) and they were randomly assigned to two nutritional treatments: 1.5 maintenance (M) (control, C) or 0.5 (M) (undernourishment, U) times the daily maintenance requirements establishing four groups: high-iBCS control (HC, n = 9), high-iBCS undernourished (HU, n = 10), low-iBCS control (LC, n = 9) and low-iBCS undernourished (LU, n = 8). High-iBCS ewes presented higher concentration of IGF-1, reflecting a better metabolic status in these animals. There was a greater proportion of high-iBCS ewes presenting more than one CL (P < 0.05), and associated greater P4 plasma concentration, number of recovered embryo and a tendency for higher embryo viability rate (P = 0.13). In uterus, undernourished ewes tended to present lower P4 (P = 0.09) and higher E2 concentration (P = 0.10). Inmunostaining of uterine progesterone and estrogen receptors (PR and ERα) was not affected by iBCS and nutritional treatment. Ewes with low-iBCS tended to have more INSR mRNA, and undernourished ewes tended to have more IGFBP2 mRNA expression (P < 0.08). An interesting finding was that the uterine response to undernutrition was dependent on iBCS: a higher expression of GHR (P < 0.05) and a tendency in IGFBP5 (P = 0.09) mRNA was found in undernourished than control ewes but only in the high-iBCS group. In summary, the present study demonstrates that the endocrine response and the uterine gene expression to undernutrition depend on the initial body energy reserves (iBCS) and appears to be associated with a differential embryo quality.

Influence of season, rainfall and air temperature on the reproductive efficiency in Romanov sheep in Croatia

The aim of this study was to investigate the influence of season, rainfall and air temperature on the reproductive efficiency in the Romanov breed of sheep in continental part of Croatia during five consecutive years (2012-2016). During this period, 5379 matings resulted in 5046 successful conceptions, i.e. lambings at eight medium-scale Romanov breed sheep farms. The conception rate was 93.81%, fecundity was 195% and average preweaning mortality until 90 days of age was 12.41%. The seasonal distribution of lambings was 47.64% for ewes that delivered in winter (n = 2422), 23.37% in spring (n = 1179), 18.82% in summer (n = 950) and 9.81% in autumn (n = 495). Sexual activity was lowest during spring and early summer when air temperatures were above average (very and extremely warm), and sexual activity peaked from August to September, especially during extremely wet and very wet seasons. Litter size was greater during winter than in other seasons (1.70 vs. 1.54) and was significantly different as compared to each of selected years of the study period. There was a statistically significant difference in the number of pregnant ewes between mating seasons. Most female Romanov lambs born during winter and early spring mated in late summer or autumn and delivered at the age of 1 year or earlier. The seasonal distribution of matings and lambing was not uniform throughout the seasons over five consecutive years. Thus, it can be assumed that air temperature and rainfall during different seasons could affect the reproductive efficiency in Romanov breed of sheep in continental part of Croatia.

Analysis of lambing distribution in the Ripollesa sheep breed. II. Environmental and genetic sources of variation

Seasonal reproduction patterns are typically observed in small ruminants and are a major limitation for production efficiency in most meat- and dairy-type production systems. Indeed, selection for reduced seasonality could be an appealing strategy for the small ruminant industry worldwide, although its genetic background has been poorly analyzed. One of the main limitations relied on the availability of appropriate analytical tools to cope with the circular (i.e. year-round) pattern of lambing and kidding data. The recent development of a heteroskedastic circular mixed model provided the statistical tool to go deeply into the knowledge of seasonality in small ruminants. In this study, 26 005 lambing distribution records from 4764 Ripollesa ewes collected in 20 purebred flocks were analyzed. The model accounted for systematic (lambing interval and ewe age), permanent environmental (flock-year-season and ewe) and additive genetic sources of variation influencing both mean and dispersion pattern (i.e. heteroskedasticity). Systematic effects suggested that first-lambing ewes and short lambing intervals delayed lambing date (~30 days) and increased dispersion of the lambing period. Nevertheless, this was partially compensated by ewe age, given that youngest females tended to concentrate the lambing peak. Flock-year-season, permanent ewe and additive genetic sources of variation reached moderate variance components for direct (and residual) effects on lambing distribution, they being 0.119 (0.156), 0.092 (0.132) and 0.195 (0.170) radians2, respectively. Moreover, all 95% credibility intervals were placed far from the null estimate. Covariances between direct and residual effects where high and positive for additive genetic (posterior mean, 0.814) and permanent ewe effects (posterior mean, 0.917), whereas it was not relevant for flock-year-season. Selection for direct additive genetic effects should be able to advance or delay the lambing peak, whereas selection applied on residual additive genetic effects should increase or reduce seasonality (i.e. concentrate or flatten the lambing peak). Moreover, the positive and relevant genetic covariance between direct and residual effects also suggested correlated genetic responses. As example, genetic selection for earlier lambing peaks must also reduce seasonality, whereas selection for narrower lambing seasons may originate a delay in the lambing peak. These results must be viewed as the first attempt to analyze systematic, environmental and genetic sources of variation of lambing distribution within the circular paradigm, they providing a reliable characterization of these effects within the context of an heteroskedastic model.

The effects of monthly air temperature and rainfall variations on the reproductive performance and lambing distribution of the Jezersko-Solčava sheep

The aim of this study was to investigate the effects of monthly air temperature and rainfall variations on the reproductive performance and lambing distribution of the Jezersko-Solčava breed in northwestern Croatia during 7 years period from 2010 until 2016. At 11 medium-scale sheep farms, the sheep were kept on a pasture in a semi-intensive environment with access to the stables. The anomalies of rainfall observed on a monthly basis during monitoring were statistically significant. Non-parametric test showed that the percentages of lambing differ among the months during the year (P = 0.0001). By using regression analysis, it was found that the percentages of pregnant sheep were linearly associated with the sequential number of the month. The seasonal distribution of lambings were 53.85% of ewes delivered in winter (n = 1296), 21.13% in spring (n = 509), 8.91% in summer (n = 215) and 16.11% in autumn (n = 387). Sexual activity was lowest during spring and early summer (from March to May) with a peak from the end of July to October. The conception rate during year 2011 was significantly lower (89.74%), and the litter size was the lowest (1.05) than in other years of the observation. Average conception rate was 92.85% and average litter size 1.21. Despite being a seasonally polyoestrous, the distribution of matings and lambings of this breed of sheep was not uniform throughout the seasons. There were established a positive or negative correlations between the air temperature and rainfall precipitation variations with tested reproductive performances of Jezersko-Solčava breed sheep in the Northwestern part of Croatia.

Changes in melatonin concentrations in seminal plasma are not correlated with testosterone or antioxidant enzyme activity when rams are located in areas with an equatorial photoperiod

In temperate climates, photoperiod and melatonin regulate ram reproduction, modulating hormonal secretions, sperm quality, and seminal plasma composition. Information on the effect of an equatorial photoperiod (12L:12D) on ram reproduction, however, is scarce, and no data on hormonal concentrations and antioxidant enzyme activity in seminal plasma have been reported. Thus, the variation was investigated of melatonin and its relationship with testosterone and antioxidant enzyme activity in the seminal plasma of three sheep breeds in Colombia, when there was a consistent photoperiod during two dry and two rainy seasons per year. Semen was collected once a week from 12 mature rams (four of each breed: Colombian Creole, Hampshire, and Romney Marsh). Seminal plasma was obtained by centrifugation. The concentration of melatonin and testosterone were quantified along with the enzymatic activity of glutathione peroxidase (GPx), glutathione reductase (GRD), and catalase (CAT). Correlation analyses between melatonin and testosterone concentrations or enzymatic activity were also performed. Melatonin concentration was affected by season (P < 0.05) but not breed, with lesser concentrations in the first rainy season. Testosterone concentration, however, was affected by breed and season, with greater concentrations (P < 0.01) in the Hampshire and Romney Marsh rams during the second dry season. Regarding antioxidant enzyme activity, there was only seasonal variation in GPx activity (P < 0.05). When correlation analyses were used for data assessments, there was a negative correlation between melatonin and testosterone concentrations in Hampshire rams. In conclusion, melatonin concentrations in seminal plasma of rams that were located in an area with an equatorial photoperiod was affected by the climatological season but there was no positive correlation with testosterone concentration or antioxidant enzyme activity.

Identification and analysis of microRNAs-mRNAs pairs associated with nutritional status in seasonal sheep

Given the important role of nutritional status for reproductive performance, we aimed to explore the potential microRNA (miRNA)-mRNA pairs and their regulatory roles associated with nutritional status in seasonal reproducing sheep. Individual ewes were treated with and without 0.3 kg/day concentrates, and the body condition score, estrus rate, and related miRNAs and target genes were compared. A total of 261 differentially expressed miRNAs were identified, including 148 hypothalamus-expressed miRNAs and 113 ovary-expressed miRNAs, and 349 target genes were predicted to be associated with nutritional status and seasonal reproduction in sheep. Ultimately, the miR-200b-GNAQ pair was screened and validated as differentially expressed, and a dual luciferase reporter assay showed that miR-200b could bind to the 3'-untranslated region of GNAQ to mediate the hypothalamic-pituitary-ovarian axis. Thus, miR-200b and its target gene GNAQ likely represent an important negative feedback loop, providing a link between nutritional status and seasonal reproduction in sheep toward enhancing reproductive performance and productivity.

Seasonality in oestrus and litter size in an assistance dog breeding colony in the United Kingdom

Evidence of seasonality in oestrus in bitches within specialist breeding programmes, such as those for assistance dogs, may support colony management through tailoring the distribution of resources required for breeding throughout the year. However, at present there are conflicting data regarding seasonality in oestrus (and litter size) in domestic dogs. The primary objective of this study was to investigate seasonal variations in oestrus and litter size in a large assistance dog breeding colony in the UK in order to optimise colony management. The authors analysed the annual distribution of 3624 observations of oestrus collected from 568 brood bitches from January 2005 to June 2014. The authors also evaluated the relationship between month and litter size for 1609 litters observed during the same period. There was no evidence of regular seasonal variations in oestrus or litter size by meteorological season or month. The lack of seasonality in oestrus may be a function of dogs in the UK, particularly valuable breeding bitches, being exposed to fairly constant environmental conditions throughout the year as a consequence of artificial light and heating during the winter months. The authors’ findings suggest that special consideration of the annual distribution of oestrus and litter size is unnecessary for the management of assistance dog breeding colonies similar to those in the UK.

Enhancing the growth performance of replacement female breeder goats through modification of feeding program

Aim:

The study was conducted at a smallholder goat farm located in Labu, Negeri Sembilan, Malaysia. The objective of this study was to evaluate the effect of proper feeding program on growth performances of replacement breeder goats.

Materials and Methods:

A total of 30 healthy female boer cross goats at the age of 4 months old with average initial live body weight (BW) of 20.05±0.5 kg were used for on-farm feeding trial to evaluate the growth performance as preparation for breeding purposes. The experimental goats were divided into two groups of 15 animals each labeled as control and treatment groups, which were kept under intensive farming system. Goats in control group were fed with normal routine feeding protocol practiced by the farmer, while goats in the treatment group were fed with new feed formulation. Throughout the experimental period, on-farm monitoring and data collection were carried out. Initial BW and body condition score (BCS) were recorded before the start of the experiment while final BW and BCS were gained after 7 months of the experimental period. Average daily gain (ADG) was calculated after the experiment end. Data on BW, ADG, and BCS were recorded from both groups for every 2 weeks and reported monthly. The feed intake for the control group was 2.8 kg/animal/day which practiced by the farmer and 3.2 kg/animal/day as new feed formulation for the treatment group.

Results:

After 7 months of the experimental period, final BW shows an improvement in treatment group (39.1±1.53 kg) compared with control group (32.3±1.23 kg). The ADG in treatment group also gives promising result when comparing with control group. Goats in treatment group significantly attained better ADG than control group which were 126.7 g/day and 83.3 g/day, respectively. For the BCS, goats in the treatment group had shown an improvement where 86.67% (13 out of 15) of the group had BCS ≥3 (1-5 scoring scale) and only 66.67% (10 out of 15) of the control group had BCS ≥3.

Conclusion:

Therefore, it was concluded that implementation of proper feeding program as shown in treatment group give promising result to improve the growth performance of replacement breeder goats which can be adopted by the farmers to improve farm productivity.

Exposure to Photoperiod-Melatonin-Induced, Sexually-Activated Rams after Weaning Advances the Resumption of Sexual Activity in Post-Partum Mediterranean Ewes Lambing in January

This study was aimed to determine whether the presence of sexually stimulated rams by photoperiodic and melatonin treatments can advance the resumption of post-partum sexual activity in Mediterranean ewes lambing in January and weaned at the end of the breeding season at 41°N, in March. Rams were exposed to two months of long days (16 h light/day) and given three melatonin implants at the end of the long days (sexually-activated rams; SAR). Control rams (CR) were exposed to the natural photoperiod. Thirty-six ewes weaned on 25 February were assigned to one of two groups. From 1 March to 30 June, one group was housed with four SAR males (SAR-treated; n = 18), and the other group (CR-treated; n = 18) was housed with four unstimulated rams. Ovulation was assessed once per week based on plasma progesterone concentrations. Estrus was monitored daily by marks left on ewes by rams' harnesses. SAR-treated ewes had a shorter (p < 0.01) weaning-first estrus interval than CR-treated ewes (61 ± 17 days vs. 102 ± 47 days; mean date of first estrus after weaning on April 26 and June 6, respectively). The proportion of the ewes ovulating in April or May was higher (p < 0.05) in the SAR-treated group than in the CR-treated group. SAR-treated ewes resumed estrous activity sooner than CR-treated ewes such that, in April, May, and June, the proportion of females that exhibited estrus was higher (p < 0.01) in the SAR-treated group (72%, 89%, and 100%, respectively) than in the CR-treated group (17%, 44%, and 61%, respectively). In conclusion, the introduction at weaning of sexually activated rams advanced the resumption of estrous activity in ewes in spring. The practical implications of this work could be important in ewes adapted for intensive production and accelerated lambing systems.

Melatonin treatment in spring and reproductive recovery in sheep with different body condition score and age

With the aim to evaluate the effect of melatonin treatment on the advanced reproductive recovery in sheep with different body condition score (BCS) and age, 800 ewes were selected from two farms. These ewes (3-6 years old, multiparous and with BCS 2.5-4.0) were subdivided into two Groups (200 M and 200 C), balanced on their BCS and age. On 20 March, Group M was treated with one melatonin implant (18 mg). Group C was untreated. Males were introduced to the groups 35 days after treatment. Gestation was diagnosed between day 45 and 90 after mating by transabdominal ultrasonography. From day 150 to 190 after rams introduction, lambing date and newborns' number were recorded. The average time in days between male introduction and lambing resulted shorter in treated than in control ewes (166.4 ± 0.48 vs. 172.5 ± 0.50) (P < 0.05). At day 160 and 170 from ram introduction the fertility rate was higher in Group M than in C (P < 0.05). The overall fertility at day 190 from rams introduction showed no differences between Group M and C (337 and 339, respectively). At day 170 from male introduction the number of the 5-6 years-old lambed ewes were 2-fold higher than the youngers (P < 0.05). The animals with a BCS 3.5-4.0 had a faster response to male effect, and a shorter mean distance in days from rams introduction to lambing, compared to those scored 2.5-3.0 (166.1 ± 0.48 vs. 174.8 ± 0.51) (P < 0.05). We concluded that the ewes with BCS 3.5-4.0 and aged 5-6 years showed a better response to melatonin treatment in spring.

The effect of periconceptional undernutrition of sheep on the cognitive/emotional response and oocyte quality of offspring at 30 days of age

Maternal periconceptional undernutrition is associated with altered development and increased risks of adverse outcomes in the offspring. This circumstance is normal in flocks under extensive farming systems, which depend on natural forage resources. The aim of this study was to determine the effect of periconceptional undernutrition in sheep on behavioral and reproductive aspects of the offspring. Eighty ewes were synchronized in estrus and allocated to two groups (n=40) to be fed diets that provided 1.5 (C) or 0.5 (L) times the requirements for maintenance. Ewes were mated and 7 days later fed the control diet until lambing. One month after lambing, 32 lambs were exposed to tests to determine their cognitive and emotional responses. Six ewe lambs were euthanized and in vitro maturation and fertilization procedures were performed. L ewes presented a significant reduction in prolificacy and fecundity (P<0.05) in comparison with C ewes. Mean LW at lambing of L lambs was significantly higher than C lambs (C: 3.80 ± 0.11; L: 4.24 ± 0.15 kg, P<0.05). Lambs born from C ewes spent more time walking than L lambs (P<0.05) in the isolation test, revealing a decrease in the locomotor activity of lambs born from undernourished ewes around conception. Ewe lambs from the undernourished ewes presented a total population of oocytes 2.3 times higher than ovaries from control ewe lambs (60.0 ± 7.8 v. 140.0 ± 18.5 oocytes; P<0.05). In conclusion, periconceptional undernutrition is able to produce an increment in the body weight and the oocyte population, and an alteration of the locomotor activity of the offspring.

Climate factors affecting fertility after cervical insemination during the first months of the breeding season in Rasa Aragonesa ewes

This study was carried out to examine the impact of several climate variables on the pregnancy rate after cervical artificial insemination (AI) of Rasa Aragonesa ewes. Data were derived from 8,977 inseminations in 76 well-managed flocks performed during the first month of the breeding season (July to October). The following data were recorded for each animal: farm, year, month of AI, parity, lambing-treatment interval, inseminating ram, AI technician, and climatic variables such as mean, maximum and minimum temperature, mean and maximum relative humidity, rainfall, and mean and maximum temperature-humidity index (THI) for each day from day 12 before AI to day 14 post-AI. Means were furthermore calculated for the following periods around AI (day 0): -12 to 0, -2 to 0, AI day, 0 to 2, and 0 to 14. Logistic regression analysis indicated that the likelihood of pregnancy decreased when maximum temperature in the 2 days prior to AI was higher than 30 °C (by a factor of 0.81). Fertility was also lower for primiparous ewes and in multiparous ewes with more than five previous parturitions. Other factors with significant impact on fertility were flock, technician, inseminating ram, and a lambing-AI interval longer than 240 days. It was concluded that the 2 days prior to AI seems to be the period when heat stress had the greatest impact on pregnancy rate in Rasa Aragonesa ewes.

Undernutrition affects embryo quality of superovulated ewes

To determine the effect of undernutrition on embryo production and quality in superovulated sheep, 45 ewes were allocated into two groups to be fed diets that provided 1.5 (control, C; n = 20) or 0.5 (low nutrition, L; n = 25) times daily requirements for maintenance, from oestrous synchronization with intravaginal sponges to embryo collection. Embryos were collected 7 days after the onset of oestrus (day 0). Low nutrition resulted in lower live weight and body condition at embryo collection (P < 0.05). Diet (P < 0.01) and day of sampling (P < 0.001) significantly affected plasma non-esterified fatty acid (NEFA) and insulin concentrations. Plasma leptin concentrations decreased on day 7 only in L ewes. A significant effect of dietary treatment (P < 0.05) and day (P < 0.0001) was observed on plasma insulin-like growth factor (IGF)-I concentrations. The number of recovered oocytes and embryos did not differ between the groups (L: 15.4 ± 0.4; C: 12.4 ± 0.4). Recovery rate was lower (P < 0.05) in the L (60%) than in the C group (73%). The total number of embryos and number of viable-transferable embryos (5.0 ± 0.3 and 3.4 ± 0.3 embryos, respectively) of the L group were lower (P < 0.1) when compared with controls (8.4 ± 0.4 and 6.2 ± 0.4 embryos, respectively). Undernutrition during the period of superovulation and early embryonic development reduced total and viable number of embryos. These effects might be mediated by disruption of endocrine homeostasis, oviduct environment and/or oocyte quality.

Seasonality of oestrus, ovulation and ovulation rate of Sicilo-Sarde sheep

This study aimed to investigate monthly changes in oestrus and ovulatory activity of Sicilo-Sarde sheep. Experimental animals comprised 25 adult and 10 maiden ewes at the start of the experiment. For 12 consecutive months (September-August), the females were exposed to natural photoperiod and permanently kept in presence of seven aproned rams. Oestrus was checked daily and ovarian activity was monitored by monthly endoscopies during the last week of each month. Ovulation rate for a particular month was assessed as the sum of corpora lutea or corpora albicans present on both ovaries at the time of endoscopy. Proportions of ewes observed in oestrus at least once a month were lowest in March (24.3%) and highest in June and October (100%). They tended (p < 0.06) to be different according to age, dropping during summer from a common value of 100% in June to 85.7% and 90% in July and then to 57.1% and 70% in August for, respectively, the Adults and Maiden females. Overall, the experimental period, 92.5% and 83.8% of Adult and Maiden ewes ovulated at least once per month (p < 0.01) respectively. Least proportions ovulating, attained 60% and 30% in April for, respectively, Adult and Maiden ewes before peaking up at 100% again in May (p < 0.05). Mean (±SD) ovulation rate of Sicilo-Sarde sheep is 1.40 ± 0.503. Adult females had a higher (p < 0.001) ovulation rate than Maiden sheep with respective average values of 1.51 ± 0.516 and 1.16 ± 0.373. It varied little between months and decreased in Adults from a maximum value of 1.95 in October to a minimum value of 1.16 in April. It is concluded that benchmarking seasonal variations of reproductive activity in Sicilo-Sarde breed would be valuable in designing improved management calendars for this breed.

Characterisation of the Melatonin Receptor 1A (MTNR1A) gene in the Rasa Aragonesa sheep breed: association with reproductive seasonality

The ovine Melatonin Receptor 1A (MTNR1A) gene was structurally characterised and association between its variants and the reproductive seasonality was examined in a daughter design comprising three families of Rasa Aragonesa sheep breed. Sequencing of six Rasa Aragonesa ewes with extreme values for seasonality trait revealed 28 polymorphisms: 11 SNPs in the coding region (all in Exon 2), and 17 SNPs in the promoter region MTNR1A. All the substitutions in the coding region were found most likely lacking any phenotypic effect, because they are conservative mutations or were not part of the transmembrane domain. The silent mutations, which had shown association with reproductive seasonality in other breeds, were also found and genotyped in Rasa Aragonesa. The T allele of SNP606/RsaI of MNTR1A gene was associated with a greater percentage of oestrous cyclic ewes in the Rasa Aragonesa breed, indicating that this SNP may be in linkage disequilibrium with a mutation responsible for this trait close to MTNR1A, or in regulatory sequences of the gene. In this sense, several SNPs affecting a binding element for some transcription factors have been identified in the promoter region. The SNPs at 422 and 527 positions could constitute a binding element for some transcription factors (TFs), located in an EF2 and SRY consensus sites in the promoter region, respectively. Haplotype h(5) showed significant differences with the h(2) haplotype (66% compared to 49.2%) on oestrous cyclicity, thus these results are consistent with genotypic associations for each SNP. Haplotype with T, A and T alleles for SNPs 422, 677 (promoter region) and 612 (Exon 2) showed an increase of the percentage of oestrous cyclic ewes. Although some of these mutations have been associated with seasonal reproduction, further studies with a more appropriate animal design as well as functional studies of TF binding activity are needed.

The interaction between photoperiod and nutrition and its effects on seasonal rhythms of reproduction in the ewe

In sheep, the seasonal patterns of reproductive activity are driven primarily by the annual photoperiodic cycle, but can also respond to other environmental factors, such as nutrition, yet little is known about the mechanisms underlying this interaction. This study was designed to define the interaction between photoperiodic and nutritional cues on seasonal patterns of ovarian activity, and to determine if there is a central interaction between these cues. Groups of Ile-de-France ewes were maintained in two nutritional states (restricted and well fed) under a simulated annual photoperiod of 8-16 h of light per day over two breeding seasons. At the end of the first breeding season, half of the animals of each group were ovariectomized (OVX) and fitted subcutaneously with estradiol implants. Low nutritional status shortened the season of ovarian activity, determined from the pattern of progesterone concentrations, by modifying the timing of seasonal transitions between periods of ovarian activity and anestrus. The same results were observed for the seasonal rhythm of neuroendocrine activity, assessed in the OVX ewes, from the pattern of luteinizing hormone concentrations. These results were then confirmed for neuroendocrine activity induced by a photoperiodic treatment. We conclude that nutrition centrally modulates the interpretation of photoperiod to affect seasonal reproductive transitions. The mechanisms of this interaction are discussed in the paper.

Use of laparoscopic intrauterine insemination associated with a simplified superovulation treatment for in vivo embryo production in sheep: a preliminary report

This study evaluated the reproductive performance of sheep that were subjected to superovulatory treatment and intrauterine insemination with two different doses of semen. The main objective was to determine whether intrauterine insemination is associated with higher rates of embryo recovery than existing procedures. In the first experiment 30 Ojalada de Soria ewes were used at the end of their productive life and nine younger ewes of the same breed were used in Experiment 2. Synchronisation of oestrus was conducted with intravaginal sponges and the superovulation treatment consisted of an intramuscular injection of 210 IU pFSH and 500 IU eCG administered 24 h before sponge removal. After 48 h of sponge withdrawal, ewes were inseminated by laparoscopy. They were divided into two groups: low dose group (LD, 25 × 106 sperm; n = 14 Expt 1 and n = 5 Expt 2) and high dose group (HD, 100 × 106 sperm; n = 14 Expt 1 and n = 4 Expt 2). Embryos were recovered 7 days after the onset of oestrus by laparotomy and uterine flushing. Two blood samples were collected in order to analyse cortisol, at sponge insertion and the day the embryos were recovered. The same protocol was repeated twice in Experiment 1, with an interval of 2 months between two consecutive treatments. Results show a significant effect of the number of recovery on ovulation rate (21.7 ± 2.2 v. 11.8 ± 1.1 corpora lutea for first and second recoveries, respectively), and number of structures recovered (11.4 ± 1.6 v. 5.2 ± 1.1, P < 0.01). Differences of embryo performance in the second recovery compared with the first one were more evident in the LD group compared with the HD group. In Experiment 2, results reflected a significant superiority of the HD group compared with the LD group, especially rate of fertilisation, which was 25% higher. Sheep producing non-fertilised embryos had higher cortisol levels at the time of flushing than those with embryos (P < 0.01). It is concluded that the use of simplified and consecutive superovulatory treatments associated with intrauterine insemination is a potential means of obtaining embryos, although the response seems to depend on donor sheep age. The use of a higher number of sperm cells per millilitre results in better outcomes in terms of embryos produced.

The effect of an intracerebroventricular injection of metformin or AICAR on the plasma concentrations of melatonin in the ewe: potential involvement of AMPK?

Background

It is now widely accepted that AMP-activated protein kinase (AMPK) is a critical regulator of energy homeostasis. Recently, it has been shown to regulate circadian clocks. In seasonal breeding species such as sheep, the circadian clock controls the secretion of an endogenous rhythm of melatonin and, as a consequence, is probably involved in the generation of seasonal rhythms of reproduction. Considering this, we identified the presence of the subunits of AMPK in different hypothalamic nuclei involved in the pre- and post-pineal pathways that control seasonality of reproduction in the ewe and we investigated if the intracerebroventricular (i.c.v.) injection of two activators of AMPK, metformin and AICAR, affected the circadian rhythm of melatonin in ewes that were housed in constant darkness. In parallel the secretion of insulin was monitored as a peripheral metabolic marker. We also investigated the effects of i.c.v. AICAR on the phosphorylation of AMPK and acetyl-CoA carboxylase (ACC), a downstream target of AMPK, in brain structures along the photoneuroendocrine pathway to the pineal gland.

Results

All the subunits of AMPK that we studied were identified in all brain areas that were dissected but with some differences in their level of expression among structures. Metformin and AICAR both reduced (p < 0.001 and p < 0.01 respectively) the amplitude of the circadian rhythm of melatonin secretion independently of insulin secretion. The i.c.v. injection of AICAR only tended (p = 0.1) to increase the levels of phosphorylated AMPK in the paraventricular nucleus but significantly increased the levels of phosphorylated ACC in the paraventricular nucleus (p < 0.001) and in the pineal gland (p < 0.05).

Conclusions

Taken together, these results suggest a potential role for AMPK on the secretion of melatonin probably acting trough the paraventricular nucleus and/or directly in the pineal gland. We conclude that AMPK may act as a metabolic cue to modulate the rhythm of melatonin secretion.

Effect of body condition score at mating on the reproductive performance of Kivircik sheep under an extensive production system

The aim of this study was to determine the effects of the body condition score (BCS) of ewes before and during the mating season on their reproductive performance under an extensive production system. In this study, 240 Kivircik sheep from the flocks of two breeders were used for over a 2-year period. The flocks were fed under extensive conditions on natural pastures throughout the year. The ewes were synchronized in two different periods, one of which was 45 days before the other. Before the introduction of rams to the ewes, the ewes were weighed after measuring their BCS. Detailed records were kept for every flock in each year. We found significant effects of BCS on pregnancy rate, lambing rate (P < 0.05) and fecundity (P < 0.05). The BCS for the highest pregnancy, lambing rate, and fecundity was determined between 2.01 and 3.00, while the lowest rates for these traits were ≤ 1.50. The highest rates of the pregnancy rate, lambing rate, and fecundity and gestation productivity were 75.9%, 70.9%, 1.11 and 3.34 kg, respectively.

Nutritional and metabolic modulation of the male effect on the resumption of ovulatory activity in goats

The present study evaluated possible modulation of the buck effect by nutritional and metabolic cues during the transition to the breeding season in adult goats with divergent bodyweight (BW) and body condition (BCS) at 27°N. In mid-February, goats (Boer × Spanish, n = 32) were assigned to receive one of the following two experimental diets to fulfill different allowances of nutritional requirements: (1) 100% (n = 16; BW = 52.3 ± 1.5 kg, BCS = 1.6 ± 0.1 units; T-100) or (2) 150% (n = 16; BW = 60.9 ± 2.4 kg, BCS = 1.6 ± 0.1 units; T-150) from February to August. Blood samples were collected to analyse thyroxine (T4), triiodothyronine (T3), non-esterified fatty acids (NEFA), triglycerides (Tg) and progesterone (P4). Final BW and BCS favoured (P < 0.001) the T-150 group (74.9 ± 2.8 v. 56.3 ± 1.4 kg, and 4.4 ± 0.2 v. 1.9 ± 0.1 units, respectively). However, mean values for NEFA, Tg, T3 and T4 did not differ (P > 0.05) between the experimental groups. Thereafter, in early August, half of the does in each diet treatment were randomly selected for determining the response to the ‘male effect’ (WM), forming the following two treatment groups: (1) T-100-WM (n = 8), or (2) T-150-WM (n = 8); the remaining does formed two groups without male exposure (WOM), as follows: (3) T-100-WOM (n = 8) and (4) T-150-WOM (n = 8). To evaluate ovarian activity, blood samples were collected from all does on Days 2–4 during the 14-day period after the male exposure. On Day 12, all does exposed to males (16/16), irrespective of the nutritional treatment, depicted ovulatory activity, whereas only 3/16 (18.75%) T-WOM does did, indicating a significant (P < 0.001) difference between these treatment groups. The increased nutritional level of the T-150 group during the anoestrous season did not result in an early onset of ovulatory activity. Does demonstrated similar metabolic hormones and concentrations of blood metabolites between the two nutritional treatments (100 v. 150% of the nutritional requirements), suggesting a high physiological plasticity between the groups, stabilising their metabolism according to the nutritional history female goats faced, and generating similar reproductive outcomes. The male effect seems to be enough to induce oestrus during the late anoestrous season, irrespective of BCS and BW.

A within farm clinical trial to compare two treatments (parenteral antibacterials and hoof trimming) for sheep lame with footrot

From observational studies, farmers who use parenteral antibacterials to promptly treat all sheep with footrot (FR) or interdigital dermatitis (ID) have a prevalence of lameness of < 2% compared with a prevalence of 9% lameness reported by farmers who treat lame sheep by trimming affected feet. We tested the hypothesis that prompt treatment of sheep lame with naturally developing FR or ID with parenteral and topical antibacterials reduces the prevalence and incidence of lameness with these conditions compared with less frequent treatment with trimming of hoof horn and applying topical antibacterials.A further hypothesis was that reduction of ID and FR would improve productivity. A lowland sheep flock with 700 ewes was used to test these hypotheses in an 18-month within farm clinical trial with four groups of ewes: two intervention and two control. The duration and severity of lameness was used to categorise sheep into three weighted scores of lameness (WLS): never lame (WLS0), mildly lame/lame for < 6 days (WLS1) and severely or chronically lame (WLS2). The intervention reduced the prevalence of lameness due to FR and ID in ewes and lambs and the incidence of lameness in ewes. The WLS was also significantly lower in sheep in the intervention groups. Ewes with a higher WLS were subsequently significantly more likely to have a body condition score < 2.5 and to have lame lambs. Significantly more ewes lambed and successfully reared more lambs that were ready for slaughter at a younger age in the intervention versus control groups. There was an increase in the gross margin of Pound630/100 ewes mated in the intervention group, including the cost of treatment of Pound150/100 ewes mated. We conclude that prompt parenteral and topical antibacterial treatment of sheep lame with ID and FR reduced the prevalence and incidence of these infectious conditions and led to improved health, welfare and productivity.

A note on the effect of level of nutrition after weaning on the resumption of reproductive activity by ewes of two Spanish breeds lambing in spring

Two experiments were carried out from April to September 1990 at Zaragoza, Spain. Fifty-three Rasa Aragonesa (RA) ewes, weaned in April, were studied in experiment 1, whilst 33 Salz (Sz) ewes, weaned in June, were studied in experiment 2. From weaning onwards, the animals were allocated to two groups receiving two planes of nutrition: high (H) and low (L). Mean time between weaning and the first detected oestrus was 113 (s.e. 2·7) and 52 (s.e. 3·0) days for RA and Sz ewes, without any significant effect of the plane of nutrition. Ewes of the H group showed a constantly higher ovulation rate than those of the L group with a significant effect of the plane of nutrition in the second fortnight of August (P < 0·05) and of September (P < 0·001) in RA ewes (1·68 v. 1·29 and 1·89 v. 1·38 corpora lutea for H and L groups, respectively) and in September (P < 0·01) in Sz ewes (2·53 v. 2·00 corpora lutea for H and L groups).

In conclusion, a slightly higher plane of nutrition after weaning in these sheep breeds, lambing in spring, cannot advance either the reproductive resumption or increase the ovulation rate of the first cycle. The high plane of nutrition after weaning exerts a significant effect on the ovulation rate in the medium term, in the early breeding season.

Control of luteinizing hormone secretion in ewes by endogenous opioids and the dopaminergic system during short seasonal anoestrus: rôle of plane of nutrition

The role of endogenous opioids and the dopaminergic system on the inhibition of luteinizing hormone (LH) secretion during early and late anoestrus, together with its modulation by the plane of nutrition were investigated in ewes with a short anoestrous season. In early anoestrus (22 March; day 0), two groups of ovariectomized, oestradiol-treated adult Rasa Aragonesa ewes, maintained under natural photoperiod at 41°N, were given enough food to provide 1·4 × (high; H; no. = 6) or 0·5 × (low; L; no. = 6) energy requirements for maintenance. The effects of administration of the opiate receptor antagonist naloxone (1 mg/kg at four 1-h intervals) (day 15) and of the dopaminergic2 receptor antagonist pimozide (0·08 mg/kg) (day 21) on LH secretion were assessed. A second experiment was carried out in late anoestrus (21 June) using the same protocol. A significant increase in LH pulse frequency after naloxone treatment for both H and L groups was detected in late anoestrus. Number ofLH pulses after naloxone injections in early anoestrus also increased in H (P < 0·05) and L ewes (P = 0·08). The effect of pimozide injection on mean LH pulse frequency was greater in early than in late anoestrus, especially in ewes receiving a high plane of nutrition (P < 0·05 and P = 0·07 for H and L ewes, respectively in April and P = 0·07 for H ewes in July). A significant increase of LH pulse amplitude was also detected in early anoestrus in H ewes (P < 0·01). These results provide evidence that endogenous opioid mechanisms are involved in the inhibition ofLH pulsatile release both in early and late anoestrus in ewes with a short seasonal anoestrus. The ability of pimozide to increase LH pulse frequency in early anoestrus could be enhanced by a high plane of nutrition in the breed studied.

Effects of exogenous melatonin on in vivo embryo viability and oocyte competence of undernourished ewes after weaning during the seasonal anestrus

This study investigated the effects of exogenous melatonin on embryo viability and oocyte competence in post-partum undernourished ewes during the seasonal anestrus. At parturition (mid-Feb), 36 adult Rasa Aragonesa ewes were assigned to one of two groups: treated (+MEL) or not treated (-MEL) with a subcutaneous implant of melatonin (Melovine(R), CEVA) on the day of lambing. After 45 d of suckling, lambs were weaned, ewes were synchronized using intravaginal pessaries, and fed to provide 1.5x (Control, C) or 0.5x (Low, L) times daily maintenance requirements. Thus, ewes were divided into four groups: C-MEL, C+MEL, L-MEL, and L+MEL. At estrus (Day=0), ewes were mated. At Day 5 after estrus, embryos were recovered by mid-ventral laparotomy and classified based on their developmental stage and morphology. After embryo collection, ovaries were recovered and oocytes were classified and selected for use in in vitro fertilization (IVF). Neither diet nor melatonin treatment had a significant effect on ovulation rate and on the number of ova recovered per ewe. Melatonin treatment significantly improved the number of fertilized embryos/corpus luteum (CL) (-MEL: 0.35 +/- 0.1, +MEL: 0.62 +/- 0.1; P = 0.08), number of viable embryos/CL (-MEL: 0.23 +/- 0.1, +MEL: 0.62 +/- 0.1; P < 0.01), viability rate (-MEL: 46.6%, +MEL: 83.9%; P < 0.05), and pregnancy rate (-MEL: 26.3%, +MEL: 76.5%; P < 0.05). In particular, exogenous melatonin improved embryo viability in undernourished ewes (L-MEL: 40%, L+MEL: 100%, P < 0.01). Neither nutrition nor exogenous melatonin treatments significantly influenced the competence of oocytes during IVF. Treatment groups did not differ significantly in the number of healthy oocytes used for IVF, number of cleaved embryos, or number of blastocysts and, consequently, the groups had similar cleavage and blastocyst rates. In conclusion, melatonin treatments improved ovine embryo viability during anestrus, particularly in undernourished post-partum ewes, although the effects of melatonin did not appear to be mediated at the oocyte competence level.

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.

Proportion of rams and the condition of ewe lambs at joining influences their breeding performance

The aim of the present study was to examine the effects of ram : ewe lamb ratio and condition score on the reproductive performance of ewe lambs. In the 2007 study, ewe lambs were bred with rams, at ram : ewe lamb ratios of 1 : 30, 1 : 50, 1 : 75 or 1 : 100. In the 2008 study, ewe lambs were bred at ratios of 1 : 31, 1 : 50, 1 : 75 or 1 : 100. Ewe lambs were bred over two 17-day periods. In both studies, ewe lambs bred in the first 17 days of breeding only were heavier (P < 0.05) than those bred in the second 17-day period only, and those ewe lambs diagnosed as twin-bearing were heavier (P < 0.05) than their single-bearing counterparts. Ewe lambs with a condition score of 2.5 or greater were more likely (P < 0.05) to be bred, and be pregnant, in the first 17 days of breeding than those of condition score 1.5 or 2.0. Over the entire 34-day breeding period, ewe lambs with a condition score of 2.5 or greater had higher (P < 0.05) pregnancy rates than those with a condition score of 2.0, which in turn had higher rates than those of 1.5. In the 2007 study, after 34 days of breeding, there were no differences (P > 0.05) in pregnancy rates among the different ram : ewe lamb ratios. While in the 2008 study, pregnancy rates after 34 days were greater (P < 0.05) in the 1 : 50 compared with both the 1 : 75 and 1 : 100 treatments. Pregnancy rates of 1 : 31 ewe lambs were greater (P < 0.05) than those of 1 : 75 ewe lambs. In the 2007 study, pregnancy rates of ewe lambs to the first 17 days of breeding were greater (P < 0.05) for those bred at a ratio of 1 : 75 than for those bred at 1 : 50, and tended to be greater (P = 0.08) than for those bred at 1 : 100. In addition, those bred at a ratio of 1 : 30 tended to have higher pregnancy rates (P = 0.07) than those bred at 1 : 50. While in the 2008 study, pregnancy rates to the first 17 days of breeding were greatest (P < 0.05) in the 1 : 31 and 1 : 50 treatments groups. In conclusion, the results of the present study indicate that achieving greater liveweights and higher condition scores of ewe lambs at breeding will increase the proportion pregnant, especially early in the breeding period. The data also suggest, in combination with the results of previous research, that farmers should consider utilising ram : ewe lamb ratios lower than 1 : 100, although further studies are warranted.