Epigenetics and developmental programming of welfare and production traits in farm animals.

The concept that postnatal health and development can be influenced by events that occur in utero originated from epidemiological studies in humans supported by numerous mechanistic (including epigenetic) studies in a variety of model species. Referred to as the 'developmental origins of health and disease' or 'DOHaD' hypothesis, the primary focus of large-animal studies until quite recently had been biomedical. Attention has since turned towards traits of commercial importance in farm animals. Herein we review the evidence that prenatal risk factors, including suboptimal parental nutrition, gestational stress, exposure to environmental chemicals and advanced breeding technologies, can determine traits such as postnatal growth, feed efficiency, milk yield, carcass composition, animal welfare and reproductive potential. We consider the role of epigenetic and cytoplasmic mechanisms of inheritance, and discuss implications for livestock production and future research endeavours. We conclude that although the concept is proven for several traits, issues relating to effect size, and hence commercial importance, remain. Studies have also invariably been conducted under controlled experimental conditions, frequently assessing single risk factors, thereby limiting their translational value for livestock production. We propose concerted international research efforts that consider multiple, concurrent stressors to better represent effects of contemporary animal production systems.

Genetic analysis of a maternal assistance score in sheep.

Maternal behaviour is important for lamb survival, as ewes perform many behaviours that affect the chances of a lamb surviving. Collecting maternal behaviour data directly at lambing is time-consuming and not considered suitable for acquiring the large volumes of data that would be required for using as selection criteria within commercial breeding flocks. The aim of this study was to investigate if a simple scoring system is heritable and assesses the expression of behaviours that reduce the probability of lamb mortality. Ewe behaviour was scored on a 3-point Maternal Assistance Score (MAS): (1) the ewe shows a high level of maternal interest (assumed if no intervention required); (2) the ewe shows limited interest in her lamb; and (3) the ewe shows no interest in her lamb. A total of 19 453 MAS were collected over 12 years, across 24 farms (including both indoor and outdoor lambing systems) and 12 different breed lines that make up the Innovis breeding programme. Ewe parity, breed, number of lambs carried, flock, lambing batch, lambing day within flock and pre-mating weight all had a significant effect on MAS (P < 0.05). The maternal assistance score was shown to be heritable (h2 = 0.05) and repeatable (0.10), positively genetically correlated to lambing difficulty (rg = 0.29) and amount of assistance the lamb required to suckle from the ewe (rg = 0.88), and negatively genetically correlated with the number of lambs successfully reared (rg = 0.49). This study shows that an easy-to-measure score can be used by shepherds with large breeding flocks, based on whether the ewe requires further assistance to support her lamb rearing. The score could be used in breeding programmes to select for lamb rearing ability in the future and potentially lead to an improvement in lamb welfare through a reduction in mortality.

Review: Exploring the use of precision livestock farming for small ruminant welfare management.

Small ruminant (sheep and goat) production of meat and milk is undertaken in diverse topographical and climatic environments and the systems range from extensive to intensive. This could lead to different types of welfare compromise, which need to be managed. Implementing Precision Livestock Farming (PLF) and other new or innovative technologies could help to manage or monitor animal welfare. This paper explores such opportunities, seeking to identify promising aspects of PLF that may allow improved management of welfare for small ruminants using literature search (two reviews), workshops in nine countries (France, Greece, Ireland, Israel, Italy, Norway, Romania, Spain, and the United Kingdom) with 254 stakeholders, and panels with 52 experts. An investigation of the main welfare challenges that may affect sheep and goats across the different management systems in Europe was undertaken, followed by a prioritisation of animal welfare issues obtained in the nine countries. This suggested that disease and health issues, feed access and undernutrition/malnutrition, maternal behaviour/offspring losses, environmental stressors and issues with agonistic behavioural interactions were important welfare concerns. These welfare issues and their indicators (37 for sheep, 25 for goats) were categorised into four broad welfare indicator categories: weight loss or change in body state (BWC), behavioural change (BC), milk yield and quality (MY), and environmental indicators (Evt). In parallel, 24 potential PLF and innovative technologies (8 for BWC; 10 for BC; 4 for MY; 6 for Evt) that could be relevant to monitor these broad welfare indicator categories and provide novel approaches to manage and monitor welfare have been identified. Some technologies had the capacity to monitor more than one broad indicator. Out of the 24 technologies, only 12 were animal-based sensors, or that could monitor the animal individually. One alternative could be to incorporate a risk management approach to welfare, using aspects of environmental stress. This could provide an early warning system for the potential risks of animal welfare compromise and alert farmers to the need to implement mitigation actions.

Parity and housing effects on the behavioural and hypothalamic-pituitary-adrenal axis responses of pregnant ewes.

It is common in many countries for sheep to be housed during winter from mid-gestation until lambing to protect ewes and lambs from adverse conditions and improve late gestation nutritional management. Keeping ewes indoors, however, has its own challenges as the animals may be mixed with unfamiliar conspecifics, have limited floor and feeding space, experience changes to their diet and increased handling by humans. Therefore, the objective of this study was to investigate the effect of variation in housing management (space allowance and social stability) on the behaviour and hypothalamic-pituitary-adrenal (HPA) axis responses of pregnant ewes from mid-to-late gestation (weeks 11-18 of pregnancy). Seventy-seven ewes (41 primiparous, 36 multiparous) were divided into two groups: 'Control' and 'Restricted space and mixed' (RS-Mix), where RS-Mix ewes were allocated half the amount of space (1.27 vs 2.5 m2 for RS-Mix and Control, respectively) and feedface (concentrate feeder space) allowance (36 vs 71 cm per ewe) given to the Control group and were also subjected to two social mixing events. Aggressive behaviour at the feedface and time spent standing, lying, walking, feeding and ruminating were recorded and faecal samples were collected for assessment of faecal glucocorticoid metabolite (FGM) concentrations. Higher aggression was observed in RS-Mix ewes during the first week of observation (P = 0.044), which gradually declined to the same level as Control ewes by the end of the study (P = 0.045). RS-Mix ewes were significantly less likely to be able to freely join the feedface compared to Controls (P = 0.022). No other significant treatment effects on aggressive behaviour or FGM during gestation were found. RS-Mix ewes displayed significantly higher ruminating behaviour at week 18 of gestation compared to Control ewes (P < 0.001), but no other effects were seen on general pen behaviour. However, the effect of indoor housing had a significant impact on primiparous ewes, who had lower weight gain (P = 0.015) and higher FGM concentrations (P = 0.014) compared to multiparous ewes regardless of treatment group. The data suggest that, although no sustained effects on behaviour or HPA axis responses were seen with the differences in space and feeder allowance or social stability at the levels used in this study, inexperienced (primiparous) ewes may find indoor housing more stressful; and are less able to adapt compared to multiparous ewes. These effects may influence the behaviour of the ewe at lambing time, and her offspring.

Genetic parameters for fitness and neonatal behavior traits in sheep.

Poor neonatal survival constrains productivity and good welfare. The heritability of survival in sheep is very low, suggesting that genetic progress will be slow. Previously we have shown that a difficult birth and low neonatal lamb vigor are important predictors of future survival. In this study we investigated the heritability of these traits, and their relationship to production traits, as an alternative indirect route to improve lamb survival. Neonatal lamb data from 11,092 animals were collected over 2 years from 290 commercial sheep flocks, using previously developed methods to rapidly assess three traits (birth assistance, lamb vigor, sucking ability) on farm. Heritabilities for neonatal traits were moderate: birth assistance (mean ± standard error; 0.26 ± 0.03), lamb vigor (0.40 ± 0.04) and sucking ability (0.32 ± 0.03). Genetic correlations between neonatal traits were moderate to high, and positive. Heritabilities for production traits were also moderate: 8-week weight (0.27 ± 0.06), 20-week weight (0.39 ± 0.07), ultrasound muscle depth (0.37 ± 0.06). Genetic and phenotypic correlations between the neonatal traits and production traits were not significantly different from zero. However, lambs that were scored as of poor vigor at birth were less likely to be recorded at 8 or 20 weeks, indicating that they may have died. The data demonstrate that the neonatal survival traits of birth assistance, lamb vigor and sucking assistance are moderately heritable when treated as a lamb trait, indicating that selection to target these lamb traits would successfully, and efficiently, improve survival without influencing productivity.

Short communication: survival, growth to weaning, and subsequent fertility of live-born dairy heifers after a difficult birth.

The experience of a difficult birth (dystocia) is traumatic and has adverse effects on the newborn in various species. Despite affecting up to 1 in 3 births in dairy cattle, studies on calves have been mostly limited to the first day of life. The objective of this study was to investigate the effects of dystocia on the survival to calving, growth to weaning, and subsequent fertility as nulliparous animals. Historical data from live-born Holstein heifer calves born from cows with various birth difficulty scores (no assistance; moderate; high difficulty) were obtained from 2 herds (Edinburgh herd: n=1,237; Crichton Royal Farm herd: n=721). Each herd was analyzed separately for birth weights, weaning weights, growth rate to weaning, number of services to conception, and age at first calving using REML and generalized linear mixed model analyses. Survival analysis (Cox proportional hazards model) was used in the Edinburgh herd to analyze the subsequent survival of live-born heifers, whereas descriptive data are presented for the Crichton Royal Farm herd. A higher mortality risk to weaning and to first service was observed in the live-born heifers that experienced moderate difficulty at birth compared with heifers born naturally. Surviving dystocial heifers had similar growth-to-weaning and fertility performance as heifers born naturally in both herds. It could be that the performance of dystocial heifers that survived to weaning was not affected or that it was compensated for by farm management. This study highlights long-term effects of the early experience of a difficult birth and thereby stresses the importance of preventing dystocia not just from the point of view of the adult cow, but also from the perspective of the calf. This would also improve farm efficiency and calf welfare.

Breed differences in fetal and placental development and feto-maternal amino acid status following nutrient restriction during early and mid pregnancy in Scottish Blackface and Suffolk sheep.

This study assessed the effect of feeding 0.75 energy requirements between Days 1 and 90 of pregnancy on placental development and feto-placental amino acid status on Day 125 of pregnancy in Scottish Blackface and Suffolk ewes carrying a single fetus. Such moderate nutrient restriction did not affect placental size, placentome number or the distribution of placentome types. Although fetal weight was unaffected by maternal nutrition, fetuses carried by nutrient restricted mothers had relatively lighter brains and gastrocnemius muscles. Suffolk fetuses were heavier and longer with a greater abdominal circumference, relatively lighter brains, hearts and kidneys, but heavier spleens, livers and gastrocnemius muscles than Blackface fetuses. Total placentome weight was greater in Suffolk than Blackface ewes. Ewe breed had a greater effect on amino acid concentrations than nutrition. Ratios of maternal to fetal amino acid concentrations were greater in Suffolk ewes than Blackface ewes, particularly for some essential amino acids. The heavier liver and muscles in Suffolk fetuses may suggest increased amino acid transport across the Suffolk placenta in the absence of breed differences in gross placental efficiency. These data provide evidence of differences in nutrient handling and partitioning between the maternal body and the fetus in the two breeds studied.

Invited review: Improving neonatal survival in small ruminants: science into practice.

Neonatal mortality in small ruminant livestock has remained stubbornly unchanging over the past 40 years, and represents a significant loss of farm income, contributes to wastage and affects animal welfare. Scientific knowledge about the biology of neonatal adaptation after birth has been accumulating but does not appear to have had an impact in improving survival. In this paper, we ask what might be the reasons for the lack of impact of the scientific studies of lamb and kid mortality, and suggest strategies to move forward. Biologically, it is clear that achieving a good intake of colostrum, as soon as possible after birth, is crucial for neonatal survival. This provides fuel for thermoregulation, passive immunological protection and is involved in the development of attachment between the ewe and lamb. The behaviour of the lamb in finding the udder and sucking rapidly after birth is a key component in ensuring sufficient colostrum is ingested. In experimental studies, the main risk factors for lamb mortality are low birthweight, particularly owing to poor maternal nutrition during gestation, birth difficulty, litter size and genetics, which can all be partly attributed to their effect on the speed with which the lamb reaches the udder and sucks. Similarly, on commercial farms, low birthweight and issues with sucking were identified as important contributors to mortality. In epidemiological studies, management factors such as providing assistance with difficult births, were found to be more important than risk factors associated with housing. Social science studies suggest that farmers generally have a positive attitude to improving neonatal mortality but may differ in beliefs about how this can be achieved, with some farmers believing they had no control over early lamb mortality. Facilitative approaches, where farmers and advisors work together to develop neonatal survival strategies, have been shown to be effective in achieving management goals, such as optimising ewe nutrition, that lead to reductions in lamb mortality. We conclude that scientific research is providing useful information on the biology underpinning neonatal survival, such as optimal birthweights, lamb vigour and understanding the importance of sufficient colostrum intake, but the transfer of that knowledge would benefit from an improved understanding of the psychology of management change on farm. Developing tailored solutions, on the basis of adequate farm records, that make use of the now substantial body of scientific literature on neonatal mortality will help to achieve lower neonatal mortality.

Breed, litter and parity effects on placental weight and placentome number, and consequences for the neonatal behaviour of the lamb.

Lamb survival is impaired in low birth weight lambs, and those that are slow to stand and suck. Many of the factors that influence lamb vigour, such as parity, litter size, and breed, may exert their effects, at least partially, before birth by influencing placenta development. Our hypothesis was that retarded lamb behavioural development was due to differences in placentation in these animals. Data were collected from Blackface and Suffolk lambs in the first 2 h after birth and placentas were collected when delivered. Suffolk lambs, which were behaviourally slower and had lower rectal temperatures than Blackface lambs, were associated with larger but less efficient placentas (placental efficiency defined as foetal weight supported per g placenta) with fewer foetal cotyledons than Blackface placentas. Triplet lambs were significantly slower than twin or single lambs to suck and had lower rectal temperatures. Although placenta efficiency increased with litter size, placenta and cotyledon weight, and cotyledon number increased with twinning but not thereafter. It seemed likely that triplet lambs suffered some placental insufficiency in comparison to other litter sizes. Lambs born to first parity mothers were slower to stand and reach the udder than lambs of more experienced ewes, and first parity ewes also had smaller and less efficient placentas although cotyledon number was not affected. Male lambs tended to be slower than female lambs for most behaviours, although rectal temperatures were not affected. The sire of the lamb also influenced lamb behaviour and rectal temperature. Both lamb sex and lamb sire influenced the average weight of placental cotyledons, thus some of the sire effect on the behaviour and birth weight of his progeny might be mediated through placental development. Lamb neonatal vigour was correlated with placental efficiency suggesting that lamb behaviour immediately after birth is related to placental development and function.

Frequency and cost of human intervention at lambing: an interbreed comparison.

The frequency of human intervention during lambing was assessed for 708 lambs and 162 ewes in up to four deliveries. In total, 21.8 per cent of the lambs born alive required some assistance at birth and 9.4 per cent were delivered manually. Assistance was required less frequently by twin lambs and ewe lambs, and Scottish blackface lambs required assistance less frequently than Suffolk lambs. Approximately one-third of the ewes were assisted in at least one delivery and 10 per cent were assisted in all their deliveries; however, less than 20 per cent of ewes were assisted more than once. A quarter of the lambs needed some human intervention to suck successfully, and Suffolk lambs needed help more frequently. The lambs born to almost half the first-parity ewes needed help to suck, but at later deliveries the lambs born to less than a third of the ewes needed assistance. In blackface flocks the survival of 100 lambs required 4.6 hours of human intervention whereas in Suffolk flocks 28 hours were required.

Pen size and parity effects on maternal behaviour of Small-Tail Han sheep.

The aim of this experiment was to study the effects of pen size and parity on maternal behaviour of twin-bearing Small-Tail Han ewes. A total of 24 ewes were allocated to a 2×2 design (six per pen), with parity (primiparous or multiparous) and pen size (large: 6.0×3.0 m; small: 6.0×1.5 m) as main effects at Linyi University, Shandong Province, China. Behaviour was observed from after parturition until weaning. All ewes were observed for 6 h every 5 days from 0700 to1000 h and from 1400 to 1700 h. Continuous focal animal sampling was used to quantify the duration of maternal behaviours: sucking, grooming and following as well as the frequency of udder accepting, udder refusing and low-pitched bleating. Oestradiol and cortisol concentrations in the faeces (collected in the morning every 5 days) were detected using EIA kits. All lambs were weighed 24 h after parturition and again at weaning at 35 days of age. The small pen size significantly reduced following (P<0.005), grooming (P<0.001) and suckling durations (P<0.05), as well as the frequency of udder refusals (P<0.001). However, there was a significant interaction with ewe parity, with decreased grooming and suckling in the small pen largely seen in the multiparous ewes (P<0.001). Independent of pen size, multiparous ewes accepted more sucking attempts by their lambs (P<0.05) and made more low-pitched bleats than primiparous ewes (P<0.001). Multiparous ewes had higher faecal oestradiol concentrations than primiparous ewes (P<0.001), and ewes in small pens had higher faecal cortisol levels compared with ewes in larger pens (P<0.001). As lambs increased in age, the duration of maternal grooming, following and suckling as well as frequency of udder acceptance and low-pitched bleating all declined, and the frequency of udder refusing increased (P<0.001 for all). Ewe parity, but not pen size, affected lamb weight gain during the period of observation (P<0.001). This is the first study to show that pen size, interacting with parity, can affect the expression of maternal behaviour in sheep during lactation. The study is also the first to report on the maternal behaviour of Chinese native sheep breeds (Small-Tail Han sheep), with implications for the production of sheep in China.

Interleukin-12 antagonist activity of mouse interleukin-12 p40 homodimer in vitro and in vivo.

Mo(p40)2 is a potent IL-12 antagonist that interacts strongly with the beta 1 subunit of the IL-12R to block binding of moIL-12 to the high-affinity mouse IL-12R. Mo(p40)2, alone or in synergy with the 2B5 mAb specific for the moIL-12 heterodimer, blocked IL-12-induced responses in vitro, Mo(p40)2 was thus used alone or with 2B5 mAb to examine the role of IL-12 in vivo, Mo(p40)2 caused a dose-dependent inhibition of both the rise in serum IFN-gamma levels in mice injected with endotoxin and the Th1-like response to immunization with KLH. Treatment with mo(p40)2 plus 2B5 anti-moIL-12 mAb also suppressed DTH responses to methylated bovine serum albumin but not specific allogeneic CTL responses in vivo. In each of these models, responses seen in mice treated with mo(p40)2 +/- 2B5 anti-moIL-12 mAb were similar to those observed in IL-12 knockout mice. Thus, mo(p40)2 can act as a potent IL-12 antagonist in vivo, as well as in vitro, and is currently being used to investigate the role of IL-12 in the pathogenesis of some Th1-associated autoimmune disorders in mice.

Physiological correlates of maternal-offspring behaviour in sheep: a factor analysis.

The onset of maternal behaviour in sheep is controlled by levels of oestrogen and progesterone in gestation and the release of oxytocin during delivery. Factor analysis was used to investigate the relationships between maternal behaviour, offspring behaviour, and maternal ovarian hormone levels during gestation in sheep. Ewes gave birth to lambs following embryo transfer between two breeds (Suffolk and Scottish Blackface), which differ in their expression of maternal behaviour. Plasma oestradiol-17beta concentration was significantly higher in Blackface ewes in the last 6 weeks of pregnancy, whereas plasma progesterone was higher in Suffolk ewes in early and mid gestation. Factor analysis revealed three factors that accounted for 50% of the total variation between variables. Factor 1 described lamb activity and had positive loadings for lamb behavioural latencies immediately postpartum, and negative loadings for sucking frequency. Factor 2 described some aspects of ewe maternal behaviour, and had positive loadings for ewe-lamb separation and lamb vocalisation, and negative loadings for ewe grooming behaviour and plasma oestradiol concentration. Factor 3 described ewe and lamb-sucking interactions, and had positive loadings for ewe moving as the lamb made sucking attempts, and negative loadings for ewe and lamb vocalisation. Factor 1 scores were significantly affected by lamb breed: Suffolk lambs received positive scores, indicating a longer latency to right and stand, whereas Blackface lambs had negative scores. Maternal progesterone concentration was significantly correlated with Factor 1 scores. Factor 2 and 3 scores were significantly affected by ewe breed. This study has shown that there are two behavioural axes to maternal behaviour in sheep, and that maternal oestradiol concentration is related to affiliative behaviours (e.g., grooming) but only weakly to ewe responsiveness to lamb-sucking attempts.

Effect of ewe and lamb genotype on gestation length, lambing ease and neonatal behaviour of lambs.

To distinguish between ewe and lamb breed effects on prenatal growth, ease of parturition and early lamb behaviour, an embryo-transfer study was carried out using a hill breed (Scottish Blackface; liveweight: 54.25 +/- 1.03 kg, mean +/- s.e.m.) and a lowland breed (Suffolk; 80.33 +/- 1.52 kg) to obtain the four possible combinations of ewe and lamb. Data were collected from 38 Blackface ewes (18 with Blackface lambs and 20 with Suffolk lambs) and 41 Suffolk ewes (20 with Blackface lambs and 21 with Suffolk lambs); all ewes were given single embryos. Suffolk lambs had a significantly longer gestation than Blackface lambs (1.5 days, P < 0.01), regardless of ewe breed. Suffolk lambs also had a longer labour (20 min, P < 0.05) and were significantly more likely to require birth assistance (17/21, 81% of all assisted deliveries; P < 0.001), as were male lambs (19/21, 90%; P < 0.01). These variables were independent of ewe breed. Blackface lambs were significantly more active than Suffolk lambs in the first 2 h after birth; ewe breed had little effect on lamb behaviour. Blackface lambs stood twice as quickly as Suffolk lambs after birth (13 min v. 24 min; P < 0.001), and were significantly more likely to suckle within the first 2 h after birth (92% v. 66%; P < 0.05). The behavioural retardation of Suffolk lambs may be a consequence of their birth difficulty which increases their likelihood of suffering birth trauma and hypoxia at parturition. Together, these factors may increase the probability of neonatal death in these lambs.

Effect of maternal undernutrition in early gestation on the development of fetal myofibres in the guinea-pig.

A 40% restriction in maternal feed intake throughout gestation in the guinea-pig results in a 35% reduction in fetal body weight at term and a 20-25% reduction in muscle fibre number. To investigate the effect of maternal undernutrition in early gestation, four nutritional treatments were used: controls-pregnant females fed ad libitum throughout gestation; TR-fed 60% ad libitum intake throughout gestation; ER-fed 60% ad libitum for the first third of gestation (until Day 25), then ad libitum to term; LR-fed ad libitum for the first 25 days, then 60% of ad libitum to term. The LR group were complicated by a high degree of fetal resorption and early littering of viable litters. The biceps brachii and soleus muscles were removed from neonates and total muscle fibre numbers determined. In a second experiment a further 8 pregnant guinea-pigs were fed 60% ad libitum until Day 15 of gestation only, and then rehabilitated onto an ad libitum diet (VER). Of these, 5 guinea-pigs were killed at term and the remaining 3 at 45 days gestation. Fetuses and placentae were obtained from all VER animals and compared with TR and controls of a similar age. Body weights were reduced in all restricted groups at term when compared with controls (P < 0.05) by 12, 40 and 50% for VER = ER, TR and LR groups, respectively. Biceps fibre number was reduced (P < 0.05) in ER, TR and LR groups by 28, 20 and 25%, respectively, but was not affected in the VER group. Soleus fibre number was not significantly affected by any nutritional treatment. Restriction for 15 days in early gestation caused a significant 20% increase in fetal weight at 45 days' gestation compared with controls, but muscle and placental weights were not affected. Analysis of placental components at Days 45 and 65 suggested that underfeeding in early gestation and subsequent refeeding caused some placental adaptations to increase the exchange-surface area. A short period of maternal undernutrition in the first third of gestation alone (ER), therefore, resulted in a biceps brachii fibre number deficit similar to that caused by restriction throughout gestation only if the period of restriction extended as far as Day 25. Furthermore, fetal weight at term was impaired by short-term nutritional restriction in early gestation. Restriction in the last two-thirds of gestation, following an ad libitum diet in the first third, caused a reduction in biceps fibre number and had a severe effect on the maintenance of pregnancy. It is probable that undernutrition in early gestation had an indirect effect on muscle fibre number by affecting the development of the placenta. This could be avoided by nutritional rehabilitation before Day 25 of gestation, but appeared to be permanent thereafter. Undernutrition after Day 25 may have had a direct effect on the development of secondary fibres.

Behavioural development in the neonatal lamb: effect of maternal and birth-related factors.

The survival of the neonate relies on the integrated expression of appropriate behaviours from both the mother and young. In precocious species, like the sheep, the speed with which the lamb stands and seeks the udder is related to lamb survival. In this study the effects of birth difficulty, lamb birth weight, ewe loss or gain in backfat from conception to delivery, ewe parity, litter size, and lamb sex on neonatal lamb behavioural development were investigated in over 500 lambs of two breeds (Scottish Blackface and Suffolk). Lambs that required assistance to be delivered were significantly slower to perform all neonatal behaviours than unassisted lambs (P<0.001), and were less active over the first 3 days after delivery (P<0.05). There were no effects of lamb birthweight that were not accounted for by the increased likelihood of requiring assistance in heavier birth weight lambs. Ewes that mobilised less body fat during their pregnancy produced lambs that stood and sucked quickly (P<0.001), and were more active over the first 3 days of life. Lambs born to first parity ewes were slower to stand and suck than lambs born to experienced ewes (P<0.001). There was an improvement in time taken by lambs to stand, seek the udder and to suck with each increase in ewe parity. Litter size had an additional retarding influence on the behaviour of multiple-born lambs that could not be accounted for by birthweight. In the Suffolk breed male lambs were slower to stand and suck than female lambs, this effect was not seen in Blackface lambs. These data demonstrate that lambs that require assistance at birth, even if they survive the birth process, lambs born to ewes that lose a lot of condition over pregnancy or first parity ewes, triplet lambs and, at least in some breeds, male lambs are slower to progress through the sequence of neonatal behaviours. These lambs are, therefore, at greater risk of not surviving to weaning.

The influence of maternal nutrition on muscle fiber number development in the porcine fetus and on subsequent postnatal growth.

In the pig, undernutrition in utero causes low birth weight, a decrease in muscle fiber number, and a reduction in postnatal growth rate. The effect on fiber number is mediated via a reduced secondary fiber population. Within a litter of pigs, lighter-weight pigs have probably suffered some deficit in muscle fiber number. In an attempt to improve the number of fibers in the lighter-weight pig fetuses, four maternal feeding regimens were used, one serving as the control. Maternal feed intake was doubled for one of three time periods during pregnancy: 1) d 25 to 50 (HE) immediately before fiber hyperplasia; 2) d 50 to 80 (HL) during fiber hyperplasia; or 3) d 25 to 80 (HT) covering both developmental events. Controls were fed at levels routinely used for pregnant sows on the farm. Sows farrowed normally and pig birth weights were recorded. Estimates were made of total myofiber number, total primary fiber number, and mean secondary:primary fiber number ratio (S:P) for the semitendinosus of each pig at 5 wk postnatal or 80 kg (HT and two control litters only). The progeny of all supplemented sows had a significantly greater mean S:P ratio (P < .05), and the HE pigs tended to have a greater number of muscle fibers than control pigs (403,840 +/- 8,197 vs 370,970 +/- 12,720). Postnatal growth rate to 80 kg was also investigated for the HT group of pigs.(ABSTRACT TRUNCATED AT 250 WORDS)

Muscle cellularity and postnatal growth in the pig.

Fast-growing strains of pigs and of other animals tend to have more muscle fibers than do slow-growing strains. The relationship between fiber number and growth rate was extended by examining pigs within the same strain. Seven litters of pigs (n = 66) were weighted at monthly intervals from birth to approximately 80 kg. The semitendinosus muscle was removed and an estimation of total fiber number, total primary fiber number, and mean secondary:primary fiber number (S:P) ratio was made for each animal. Pig growth was divided into three approximately linear phases: birth to 6 kg, 6 to 25 kg, and 25 kg to slaughter weight. Average daily gain in the first two phases was correlated with birth weight (r = .3614, P < .05 and r = .5873, P < .001, respectively) but was not correlated with total muscle fiber number. In the third growth phase ADG was correlated with muscle fiber number (r = .4149, P < .001) and was not correlated with birth weight. The gain:feed ratio was also calculated for each pig during the third growth phase and was found to be correlated with fiber number (r = .4191, P < .001). These results suggest that muscle fiber number is an important determinant of postnatal growth such that pig littermates with a high fiber number tend to grow faster and more efficiently than littermates with a lower fiber number.

Maternal behaviour and lamb survival: from neuroendocrinology to practical application.

Parental care promotes offspring survival and, for livestock species, this care is provided solely by the mother. Maternal behaviour in the sheep has been exceptionally well-studied compared with other species and many of the underpinning biological processes leading to the expression of maternal care are known. In this review the current state of play with regard to the biology of maternal care will be reviewed, and its application to provide practical solutions to reduce lamb mortality considered. For maternal care to be elicited at birth the ewe requires elevated circulating oestradiol in late gestation, which stimulates the expression of oxytocin receptors in both peripheral and central areas (particularly the hypothalamic and limbic areas of the brain). At birth stretching of the vaginocervical canal elicits a spinal reflex which triggers the release of oxytocin primarily from neurones within the paraventricular nucleus of the hypothalamus. Oxytocin release causes an increase in the neurotransmitters noradrenaline, acetylcholine, glutamate and γ-aminobutyric acid (GABA) in the olfactory bulb, and other brain regions important for maternal behaviour. Finally, sensory cues provided by the lamb, in particular the amniotic fluids surrounding it, lead to the expression of maternal behaviours (licking, low-pitched bleats, acceptance of the lamb at the udder and suckling). This allows the expression of the two facets of maternal behaviour in the ewe: nurturance of the young and maternal selectivity, whereby a specific olfactory memory for the ewes own lamb is formed and the expression of maternal care is restricted to this lamb. Variation in the expression of maternal care has been demonstrated in primiparous ewes compared with multiparous, in different sheep genotypes, with undernutrition, stress in pregnancy, following a difficult delivery, and may occur with variation in ewe temperament. An understanding of the importance of the timing of various events in late pregnancy and during parturition, as well as the factors that can disrupt these events, can help to design management activities to minimise risks to the successful onset of maternal behaviour. Management practices that work with the biology of the ewe will be the most successful in ensuring that maternal care is expressed, so improving the welfare of the ewe and lamb, and the profitability of the farm.

Stillbirth in dairy calves is influenced independently by dystocia and body shape.

The objectives of this study were to determine (1) if stillborn calves born following dystocia present with specific injuries/pathological changes compared to stillborns delivered without difficulty, and (2) whether such stillborns differ in conformation from dystocic calves that survive. Post-mortem examinations were carried out on 20 stillborns that were either unassisted (N) or were 'farm-staff'-assisted/normally presented (FN) at birth. Evidence of greater trauma and bruising was observed in the FN calves and parameters such as body length, birth-weight and thyroid:body weight were similar. In a second part of the study birth-weight, body length and height, girth length, body mass (BMI), and ponderal (PI) indices were assessed in 490 calves. Regardless of the severity of dystocia, stillborns had greater body lengths and lower BMIs and PIs than calves born alive (P<0.05), suggesting prenatal factors contribute to their post-natal survival. FN calves were heavier than N calves (P<0.05), and both FN and farm-staff-assisted/malpresented calves had lower PIs than N calves (P<0.05). The study found that criteria such as grossly visible carcass haemorrhage, bruising, and brain congestion were not reliable in terms of identifying calves that had experienced dystocia. Half of the stillborns had breathed indicating they were alive and possibly had experienced pain/distress at time of delivery. Body conformation was related to stillbirth independently of dystocia, a finding likely reflecting inadequate prenatal development.