Cathy M. Dwyer

Ewe–lamb bonding behaviours at birth are affected by maternal undernutrition in pregnancy

Maternal undernutrition in pregnancy results in low birth-weights and impaired postnatal survival in sheep. Largely anecdotal evidence suggests that the expression of appropriate maternal and neonate behaviours may also be disrupted by undernutrition. In the present study, we investigated the effect of a moderate (35 %) reduction in ewe nutritional intake in pregnancy on the expression of ewe-lamb bonding behaviours in primiparous Scottish Blackface ewes. Low-intake (L) ewes had significantly higher plasma progesterone than high-intake (H) ewes from mid-gestation onwards (e.g. plasma progesterone at 20 weeks (ng/ml): H 15.72, L 22.38, sed 1.80, P<0.001), and a lower oestradiol: progesterone value than H ewes at delivery (H 0.46, L 0.35, sed 0.05, P<0.05). Lamb birth-weight was reduced in the L lambs compared with H lambs (mean body weight (kg): H 3.31, L 3.00, sed 0.14, P<0.05), but the incidence of malpresentation at delivery was greater in L lambs. L ewes spent significantly less time licking their lambs than H ewes after delivery (time grooming in 2 h after birth (%): H 56.12, L 48.17, sed 2.639, P<0.01) and were more aggressive towards the lambs. Lamb behaviours were not directly affected by maternal nutritional treatment, but lamb birth-weight had a significant effect on neonatal developmental progress. Low-birth-weight lambs were slower than heavier lambs to stand and sucked less frequently. In tests of maternal attachment to the lamb, H ewes received higher scores than L ewes at both 24 h after birth (ewes receiving high scores (%): H 41.3, L 21.4, P<0.05) and at 3 d postnatal. We conclude that even a moderate level of undernutrition impairs the attachment between ewes and lambs by affecting maternal behaviours expressed at birth. In addition, the results suggest that levels of nutrition resulting in a decrease in birth weight will affect neonatal lamb behavioural progress.

Variability in the expression of maternal behaviour in primiparous sheep: Effects of genotype and litter size

Abstract The effects of ewe genotype and litter size on the expression of maternal behaviour in primiparous sheep were investigated using a lowland breed selected for growth (Suffolk) and a less-selected hill breed of sheep (Scottish Blackface). Focal animal observations were carried out on 58 Blackface (37 singles and 21 twins) and 57 Suffolk ewes (20 singles and 37 twins) during the 2 h after the birth of each lamb. Overall labour was shorter for Blackface ewes compared to Suffolk ewes (62 vs. 84 min, respectively, P P =0.05) and more by single lambs than twins. Although some aspects of negative maternal behaviour were shown by both breeds of primiparous ewe, Suffolk ewes were more likely to abandon a lamb ( P =0.063), and were significantly more likely to be aggressive towards their lamb ( P P P P P P P

Ewe-ewe and ewe-lamb behaviour in a hill and a lowland breed of sheep: a study using embryo transfer.

Domestic sheep have a strong social tendency. The nature of this gregariousness, however, varies with season, breed, sex and age. In this study the social behaviour of two breeds of ewe (Suffolk and Scottish Blackface) was investigated over two years in two different environments. In addition, to examine whether lamb behaviour would affect the behaviour of the ewe, an embryo transfer study was carried out between the two breeds resulting in four combinations of ewe and lamb (Blackface ewe with Blackface lamb, n=25; Blackface ewe with Suffolk lamb, n=24; Suffolk ewe with Suffolk lamb, n=25; Suffolk ewe with Suffolk lamb, n=25). All ewes and lambs grazed together in Field 1 (year 1) and Field 2 (year 2). Field 1 was 9 ha and rather uniform; Field 2 was 21.4 ha and had two distinct regions: an upland and a lowland area. Blackface ewes preferentially associated with their own lamb whereas Suffolk ewes associated equally with their own lamb or another Suffolk ewe, there was no effect of lamb breed (percent observations with own lamb as nearest neighbour, Field 1: Blackface ewes=50.2%, Suffolk ewes=43.5%, P<0.05; Field 2: Blackface ewes=73.1%, Suffolk ewes=43.5%, P<0.001). Blackface ewes were also significantly closer to their lambs than Suffolk ewes, regardless of year or lamb breed (Blackface ewes=6.10 m, Suffolk ewes=11.54 m, P<0.001). When own lamb was not the nearest neighbour ewes associated with other ewes of the same breed as themselves (With same-breed ewe=88.4% of observations, with other-breed ewe=11.6%, P<0.001). In Field 1 the distribution of both breeds in the field was similar to one another but ewes maintained subgroups composed predominantly of their own breed (P<0.001). The mean distance between ewes was the same for both breeds, however subgroups were significantly smaller for Blackface ewes (7.53 and 9.26 ewes for Blackface and Suffolk respectively, P<0.001). In Field 2 Blackface ewes were found mainly in the upland region of the field whereas Suffolk ewes were almost exclusively in the lowland areas. Mean distance between ewes increased markedly for Blackface ewes when compared to ewe–ewe distance in Field 1 but was unchanged for Suffolks (11.29 vs. 4.36 m for Blackface and Suffolk ewes respectively, P<0.001). Subgroup size also declined for Blackface ewes in comparison to Field 1 but increased for Suffolks (Blackface=3.10, Suffolk=11.31 ewes, P<0.001). Lamb breed had no effect on the social behaviour of either breed of ewe. The two breeds had differing behaviour in their relationship to their own lamb. Their relationship to other ewes, however, was significantly modified by the environment although the Blackface breed was less gregarious than the Suffolk under both conditions.

Effect of a difficult calving on the vigour of the calf, the onset of maternal behaviour, and some behavioural indicators of pain in the dam

The neonates development and survival is dependent upon being vigorous at birth and receiving appropriate maternal care. However, difficulty at delivery can result in less vigorous offspring and maternal care can be altered, probably as a consequence of exhaustion, pain and human intervention. The first 3h after expulsion of the calf were observed continuously from videos following twelve natural calvings and sixteen calvings assisted by farm staff (including four malpresentations) from Holstein cows. Calvings were balanced within groups for parity of the dam, genetic group, sex and birth weight of the calf, calving pen and calving season. Assisted calves were less vigorous with higher latencies to attempt to stand, achieve standing, walk and reach the udder than unassisted calves (P<0.05). Furthermore, assisted calves also tended to be less likely to stand and walk within the first 3h after birth (P<0.1), spent more time lying on their flank (P=0.019) and had more frequent bouts of this behaviour (P=0.033). Assisted dams did not take longer to lick the calf and performed as much licking as unassisted dams (P>0.05), indicating no delayed onset or impaired expression of maternal behaviour in dams given assistance at delivery. Study of potential pain-related behaviours revealed that assisted dams spent less time self-grooming (P=0.033) than dams delivering naturally, which could suggest greater pain. However, there were no significant differences in any of the other pain-related behaviours. Our results suggest that, although maternal behaviour was unaffected by a difficult delivery, dairy calves born following difficult calvings have lower vigour in the first 3h after birth than unassisted calves. This might have longer-term effects on the health and survival of the calves.

Prepartum plasma estradiol and postpartum cortisol, but not oxytocin, are associated with interindividual and breed differences in the expression of maternal behaviour in sheep

Consistent, individual differences in the expression of maternal behaviour have been described in several species including the sheep. The neuroendocrine mechanisms underlying the onset of maternal behaviour in the sheep have been described, although the relationship between hormonal events and individual differences in behaviour has yet to be determined. In this study, we examined whether the individual differences in plasma estradiol, progesterone, oxytocin and cortisol concentrations were related to observed individual and breed differences in maternal behaviours in two breeds of sheep (Scottish Blackface and Suffolk) known to differ in maternal behavioural expression. Maternal estradiol concentration increased rapidly before parturition and was higher in Blackface ewes than Suffolk ewes. Plasma progesterone declined before parturition and was higher in Suffolk than Blackface ewes. Prepartum estradiol, but not progesterone, was related to individual differences in maternal grooming of the lamb. Plasma oxytocin did not differ between breeds in late gestation. There was a tendency for oxytocin to be higher in Blackface than Suffolk ewes immediately after birth. However, there were no significant relationships between prepartum or postpartum oxytocin and any maternal behaviours. Plasma cortisol was higher in Blackface than Suffolk ewes in the last days of pregnancy but rose in both breeds over the last 24 h before parturition and did not differ at delivery. Cortisol peripartum was negatively related to individual differences in maternal affiliative behaviours. These data suggest that estradiol, and potentially cortisol, may mediate individual differences in maternal behaviour in sheep.

Genetic selection for extensive conditions

Abstract Humans have selected animals which are more suited for food production or other purposes, since the process of domestication of livestock began, whether this selection was done knowingly or unknowingly. The deliberate selection of improved breeds and strains has been a particularly important feature of agriculture in the last couple of centuries, especially in the industrialised countries. For most of this period, selection has been based on subjective assessment of the merits of animals, but objective tools for selection (e.g. performance recording and statistical methods for evaluation of genetic merit) have become widely used in the last few decades. These tools have been used to a large extent in pig, poultry and dairy cattle breeding, but to a much lesser extent in the beef cattle and sheep breeds common in extensive production systems. However, these extensive systems themselves have changed to a much lesser extent than those in which pigs and poultry are kept. Hence there have been opportunities for natural selection for traits conferring better adaptation to these environments. Additionally there has been some subjective selection for traits thought to confer better adaptation. There is considerable scope for wider uptake of existing objective methods of genetic improvement in the harsher areas of the UK, and elsewhere. However, these methods are likely to be more effective if the genetics of traits conferring adaptation to harsh environments are better understood, and if the most important of these traits are included in the breeding goal. Traits conferring better adaptation may include physical attributes such as litter size, fleece type and the ability to store body fat, some aspects of behaviour, especially maternal and grazing behaviour, and disease resistance. A better understanding of the relationships between production traits and these adaptation traits will also be critical for the development of appropriate, sustainable breeding programmes. This approach should reduce the risk of there being detrimental correlated effects of selection, and may provide opportunities to improve animal welfare.

The impact of dystocia on dairy calf health, welfare, performance and survival

Up to one-third of dairy calves are born after dystocia and this is a major cause of calf mortality. This study investigated the neonatal physiology, survival, health and subsequent growth of dairy calves following dystocia and is the first longitudinal study to analyse multiple effects and to look beyond the perinatal period. A total of 455 live born Holstein calves (N: No assistance, n=360; FN: Farmer assistance but normally presented calf, n=82; FM: Farmer assistance of malpresented calf, n=13) were followed from birth to first service (heifers) or until leaving the farm (bulls). Compared to N calves, FN and FM animals had higher salivary cortisol concentrations at day 1 (P<0.001) and FN calves had lower passive immune transfer (P=0.03). Dystocia had no biologically significant impact on rectal temperature throughout the first 4 days (P>0.05). During the first 60 days, FM calves had a higher proportion of days with non-routine health treatments (P<0.05) and, by the time of weaning, mortality in FN and FM heifers was higher than in N calves (2.8×; P<0.01). However, in surviving calves, growth to first service was not affected by dystocia category (P>0.05). Calves which survive dystocia experience lower passive immunity transfer, higher mortality and higher indicators of physiological stress. Such calves have poorer welfare in the neonatal period and possibly beyond. Strategies need to be implemented to improve the subsequent health and welfare of such calves and to lower the incidence of dystocia.

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.

Factors affecting dystocia and offspring vigour in different sheep genotypes

Birth difficulty and poor lamb vigour are significant causes of perinatal lamb mortality. In this study we investigated whether sheep breeds differing in appearance, muscularity and selection history also had differences in dystocia and lamb vigour, and considered some of the factors that may contribute to the variation in these traits. Data were collected at birth from a total of 3252 lambs of two terminal sire breeds selected for lean growth (Suffolk [S], n=500 and Texel [T], n=1207), from a Hill breed (Scottish Blackface [B], n=610), which has been mainly selected for hardiness, and a crossbred (Mule×T [M], n=935) representing a maternal line. For each lamb the degree of assistance at delivery, lamb presentation, amount of assistance to achieve successful sucking, sex, litter size and birth weight were recorded. T lambs required the most, and B and M lambs the least assistance at birth, S lambs were intermediate (% lambs assisted: T=55.7, S=30.7, B=22.7, M=24.9, P<0.001). T and S lambs were equally likely to be malpresented at birth (29% of births) and more likely to be malpresented than B or M lambs (20%; P<0.001). In T and S breeds lambs requiring veterinary assistance at delivery were mainly heavy and singleton lambs, whereas in B and M breeds these were exclusively low birth weight lambs in multiple litters. Although heavier lambs needed greater birth assistance, T lambs were lighter than S and M lambs, but heavier than B lambs (birth weight (kg): S=4.66, M=4.56, T=4.32, B=3.67, P<0.001). S lambs were more likely to require assistance with sucking than other breeds, and T lambs also required more assistance than B or M lambs (% lambs assisted to suck: S=56.0, T=31.6, M=19.8, B=18.4, P<0.001). Heavier lambs were more likely to suck unaided than lighter lambs (P<0.001). The data suggest that the two terminal sire breeds, selected narrowly for greater productivity (muscle growth and conformation), are more likely to experience birth difficulty and poorer lamb vigour than the breed selected for hardiness, or the cross breed. Whether these effects arise as a consequence of genetic selection (e.g. for specific lamb conformation), or as a result of management practices to achieve selection goals (e.g. increased intervention at lambing) is unknown. Specific actions to improve birth difficulty and lamb vigour, such as including these traits in the selection index, would be beneficial in improving the welfare of ewes and lambs of the terminal sire breeds.

Interactions between profit and welfare on extensive sheep farms

Extensive sheep farming systems make an important contribution to socio-economic well-being and the ‘ecosystem services’ that flow from large areas of the UK and elsewhere. They are therefore subject to much policy intervention. However, the animal welfare implications of such interventions and their economic drivers are rarely considered. Under Defra project AW1024 (a further study to assess the interaction between economics, husbandry and animal welfare in large, extensively managed sheep flocks) we therefore assessed the interaction between profit and animal welfare on extensive sheep farms. A detailed inventory of resources, resource deployment and technical performance was constructed for 20 commercial extensive sheep farms in Great Britain (equal numbers from the Scottish Highlands, Cumbria, Peak District and mid-Wales). Farms were drawn from focus groups in these regions where participative research with farmers added further information. These data were summarised and presented to a panel of 12 experts for welfare assessment. We used two welfare assessment methods one drawn from animal welfare science (‘needs’ based) the other from management science (Service Quality Modelling). The methods gave complementary results. The inventory data were also used to build a linear programme (LP) model of sheep, labour and feed-resource management monthby-month on each farm throughout the farming year. By setting the LP to adjust farm management to maximise gross margin under each farm’s circumstances we had an objective way to explore resource allocations, their constraints and welfare implications under alternative policy response scenarios. Regression of indicators of extensification (labour per ewe, in-bye land per ewe, hill area per ewe and lambs weaned per ewe) on overall welfare score explained 0.66 of variation with labour and lambs weaned per ewe both positive coefficients. Neither gross margin nor flock size were correlated with welfare score. Gross margin was also uncorrelated with these indicators of extensification with the exception of labour/ewe, which was negatively correlated with flock size and hence with gross margin. These results suggest animal welfare is best served by reduced extensification while greater profits are found in flock expansion with reduced labour input per ewe and no increase in other inputs or in productivity. Such potential conflicts should be considered as policy adjusts to meet the requirements for sustainable land use in the hills and uplands.