Progesterone administration reduces the behavioural and physiological responses of ewes to abrupt weaning of lambs

Temporary sensory separation of lamb groups from ewes affects behaviors and serum levels of stress-related indicators of small-tailed Han lambs

Under the current meat sheep breeding system, newborn lambs usually live with their mothers until weaning, and in daily management, they often need to be separated from their ewes for a short period due to dehorning, disease treatment, etc. Such short-term separation was considered to be a high-intensity stress for the lambs. This study aimed to explore the effects of 1 h sensory separations on behaviors and the concentration of stress-related indicators of small-tailed Han lambs. Lambs were assigned to four groups: auditory, visual, and tactile separation (AVT) group; visual and tactile separation (VT) group; tactile separation (T) group; and control (C) group. Then they were separated from their mothers for one hour on postnatal days 14, 21, 28, 35 and 42. Results showed the separated lambs (AVT, VT, and T groups) spent less time lying down relaxing and more time looking around, exploring, vocalizing, and attempting to escape (P < 0.05). Lambs separated by lack of tactile contact only exhibited the most escaping and moving behavior. Twin-born lambs showed less moving, escaping, and vocalizing than single-born lambs (P < 0.05). The separation also led to a rise in serum globulin levels and a decrease in tetraiodothyronine. In conclusion, this study showed that temporary 1 h ewe-lamb separations could affect behaviors and the serum levels of stress indicators of lambs. The behavioral responses were more obvious when lambs were separated by lack of tactile contact only, and in single-born lambs. It can conclude that indicated that when lambs need to be temporarily separated from ewes in daily management production, it would be better to let them stay together with their littermates, and make them avoid hearing or seeing the ewes, such management may partially reduce the separation stress, thereby improving the welfare and breeding efficiency of sheep.

Review of yeast culture concerning the interactions between gut microbiota and young ruminant animals

Microorganisms inhabit the gastrointestinal tract of ruminants and regulate body metabolism by maintaining intestinal health. The state of gastrointestinal health is influenced not only by the macro-level factors of optimal development and the physiological structure integrity but also by the delicate equilibrium between the intestinal flora and immune status at the micro-level. Abrupt weaning in young ruminants causes incomplete development of the intestinal tract resulting in an unstable and unformed microbiota. Abrupt weaning also induced damages to the microecological homeostasis of the intestinal tract, resulting in the intestinal infections and diseases, such as diarrhea. Recently, nutritional and functional yeast culture has been researched to tackle these problems. Herein, we summarized current known interactions between intestinal microorganisms and the body of young ruminants, then we discussed the regulatory effects of using yeast culture as a feed supplement. Yeast culture is a microecological preparation that contains yeast, enriched with yeast metabolites and other nutrient-active components, including β-glucan, mannan, digestive enzymes, amino acids, minerals, vitamins, and some other unknown growth factors. It stimulates the proliferation of intestinal mucosal epithelial cells and the reproduction of intestinal microorganisms by providing special nutrient substrates to support the intestinal function. Additionally, the β-glucan and mannan effectively stimulate intestinal mucosal immunity, promote immune response, activate macrophages, and increase acid phosphatase levels, thereby improving the body's resistance to several disease. The incorporation of yeast culture into young ruminants' diet significantly alleviated the damage caused by weaning stress to the gastrointestinal tract which also acts an effective strategy to promote the balance of intestinal flora, development of intestinal tissue, and establishment of mucosal immune system. Our review provides a theoretical basis for the application of yeast culture in the diet of young ruminants.

Social Stress during the Estrus or Luteal Phase in Sheep

In mammals, progesterone and estrogens affect the stress response. The study aimed to compare the physiological and behavioral responses to the social isolation of ewes during the estrus or luteal phase. Estrous and diestrous ewes (n = 10 and 8 respectively) were individually isolated in a novel place for 10 min. Ewes' behavior was recorded during the test. Cortisol, blood proteins and glucose concentrations, and the skin surface temperature were determined before and after the test. Cortisol increased immediately after the test ended (P = 0.02). Serum total protein (P = 0.02), globulin (P < 0.0001), and plasma glucose (P = 0.006) concentrations were greater in estrus than in the luteal phase. The abdominal skin surface temperature was greater during estrus than during the luteal phase (P = 0.02). Ewes in estrus spent more time standing up immobile than ewes in the luteal phase (P = 0.05). In conclusion, the physiological and behavioral responses changed according to the phase of the estrous cycle. These results highlight the need for future studies focusing on how reproductive status influences the stress response to different management practices in sheep.

Administration of a single dose of long-acting injectable progesterone formulation reduces the stress response to weaning in anestrous ewes

High circulating progesterone concentrations decrease the responses to stressful situations in farm ruminants. We hypothesized that administering a single dose of long-acting progesterone formulation reduces the stress response of anestrous ewes to weaning. The aim of this study was to compare the behavioral, cortisol, and blood protein responses to weaning of anestrous ewes treated or not, with a single dose of a long-acting progesterone formulation. A complementary aim was to characterize the bioavailability of progesterone after this treatment. Thirty-six multiparous single-lambing Corriedale ewes and their lambs were used in this study. The lambs were weaned at 6:30 h when they were 65 d old (d0), and were taken to another paddock without chemical, visual or auditory contact with their mothers, while the ewes remained in the same paddock. Immediately before weaning, while 19 ewes received oil based long-acting progesterone formulation, other 17 ewes remained as controls, receiving sunflower oil. Twelve ewes from each group were used for behavioral recordings, the other 5 untreated ewes and 7 treated ewes were used to characterize the cortisol response and the progesterone profile. Behaviors were recorded every 10th min for 3 h in the morning and 3 h in the afternoon on day minus 3, d0 and d2, and expressed as percentage of recordings each animal displayed each behavior on each day. Treated ewes were recorded more times standing up than ewes on the day of weaning (P < 0.05), but the reverse result was found 2 d after (P < 0.01). Treated ewes were recorded more times lying down than control ewes on d2 after weaning (P < 0.0001), when treated ewes were observed fewer times walking than control ewes (P = 0.0004), as also happened the day of weaning (P < 0.0001). On the day of weaning, treated ewes grazed and paced less than control ewes (P = 0.001 and P = 0.009). Treated ewes ruminated more than control ewes on the day of weaning (P = 0.02) and 2 d later (P = 0.0002). Control ewes also secreted more cortisol than progesterone-treated ewes (P = 0.03), with no effect of the treatment on the concentration of total proteins, albumin or globulins. While control ewes never had luteal progesterone concentrations (>0.5 ng/mL), treated ewes achieved luteal progesterone concentrations 2 h after its administration, and remained well above luteal levels until 15 h after administration. The administration of a single dose of long-acting progesterone formulation appears to be a viable choice in reducing the stress to weaning in ewes. Ewes treated with progesterone coped better with weaning, returning to their normal basal behavior earlier than untreated ones, and secreting lower cortisol levels.

Lambs are more stressed at early weaning when housed with their twin

The objective of this study was to compare the behavioural and immunological responses of twin lambs housed together with their siblings or not after weaning. The study was performed with seven multiparous Milchschaf ewes and their twin lambs (n = 14), which were weaned abruptly at 63 days of age and assigned to two experimental groups: (1) lambs that were housed together with their sibling after weaning (group GT, n = 6) and (2) lambs that were separated from their siblings and remained with other lambs from the same flock (group GS, n = 8). Before and after weaning, the distance between twins, the number of times in which the sibling was the closest lamb, the lambs' behaviours, and the average daily gain were recorded. The lambs' immune response was assessed with the phytohemagglutinin skin test after weaning. The closest lamb before weaning was the sibling in all cases (P < 0.0001 for all). The frequency in which GT lambs were observed closest from its twin increased on the day of weaning (P = 0.002). During the day of weaning, GT lambs vocalised and paced more than GS lambs (P = 0.001 and P = 0.01, respectively). Twenty-four h after the phytohemagglutinin injection, the skinfold thickness was greater in GS than GT lambs (P = 0.03). In conclusion, twin lambs housed together with their siblings were more stressed at weaning, displaying more intensive behavioural changes and a poorer immunological status than twin lambs housed separated from their siblings.

What Do We Know and Need to Know About Weaning in Sheep? An Overview of Weaning Practises, Stress and Welfare

Artificial weaning is the separation of the mother and her lamb, involving the forced ending of suckling and milk supply by the ewes to their lambs. Artificial weaning time varies depending on the purpose of each sheep farm and the characteristics of the lambs, including age and weight of the lambs, and their ability to eat solid food. Artificial weaning is performed from 24 h postpartum until around the age of natural weaning (up to 12 mo of age). Artificial weaning results in the breaking of the ewe-lamb bond, the end of suckling and the complete replacement of milk by solid food, frequently added to changes in both the physical and social environment. It triggers behavioural, physiological and immunological changes that generate negative consequences on the health of both ewes and lambs, as well as on the growth of the lambs, rising animal welfare concerns. As artificial weaning is considered one of the most stressful situations in the life of farm mammals, it is important to consider the factors involved in those responses to develop adequate strategies and improve sheep welfare at weaning. The most frequently used method is the abrupt separation of the ewes and their lambs. However, the adaptation of the animals after weaning can be improved by alternative weaning methods (e.g., progressive, two-steps weaning and mixed regimes), hormonal treatments (e.g., administration of progesterone), and pre- and postweaning management (e.g., the use of creeping feeding, and the presence of conspecifics or humans after weaning). This review presents and summarises information on the stress response and animal welfare issues at artificial weaning in sheep and some management practises that can be used to reduce these problems. The major points included are the ewe-lamb bond at birth and during the lactation period; the stress response at weaning; the factors involved in the stress response at weaning; the different types and weaning methods and their repercussions on animal welfare; and some strategies that can be used to improve sheep welfare at weaning. Lastly, we propose directions for research needed to develop practical alternatives to minimise sheep's stress response at weaning.

Regulation of maternal behavior, social isolation responses, and postpartum estrus by steroid hormones and vaginocervical stimulation in sheep

Periparturient ewes display several activities in addition to maternal behavior per se. They isolate themselves from the flock and, contrary to other mammals, do not show postpartum estrus. We investigated the possibility of a common hormonal control of maternal behavior, prepartum social isolation responses, and absence of postpartum estrus. We quantified responses to flockmate separation and incidence of sexual receptivity at several reproductive stages in intact ewes (Experiment 1). Responses to social isolation were lowest in preparturient ewes and at pregnancy day 149, intermediate at pregnancy day 147 and highest at day 136 and in non-pregnant ewes (P < 0.05 between the 3 levels). In a second experiment, we quantified the same parameters and maternal behavior in 1) ovariectomized ewes receiving medroxyprogesterone acetate only (ovxMPA); 2) ovariectomized ewes receiving MPA + estradiol benzoate (ovxSHORT); 3) intact ewes receiving a longer MPA + estradiol dipropionate treatment, before and after vaginocervical stimulation (VCS). Before VCS no steroid treatments decreased social isolation responses and maternal behavior was scarce or absent. Following VCS and interaction with lamb, maternal responses in the ovxSHORT group increased while social isolation responses decreased. Sexual receptivity occurred in non-pregnant ewes and in ovxSHORT group. Conclusion: some hormonal treatments +VCS can effectively induce maternal behavior and reduce social isolation responses. Long-term progestin treatment can inhibit postpartum estrus.

Review: Management of livestock behavior to improve welfare and production

In animal production, producers face different problems inherent to production systems. Today society is increasingly concerned about more sustainable systems and animal welfare. Applied ethology can be a tool to solve some of these problems through these approaches. The purpose of this review is to show succinctly some sustainable behavioral technologies whose application favors animal welfare and productivity. The examples cover areas of behavioral problems associated with multiple births, where odor transfer can be used to substitute or add newborns to a foster mother; early weaning, where some alternatives for a gradual break may reduce the stress of separation; early experience on the development of food preferences, where behavioral problems like neophobia can be avoided; early detection of sick animals, where recognition of some specific behaviors could help early identification of diseases, even before the appearance of clinical signs; social isolation on ease of handling, where different techniques have proved their effectiveness modifying the temperament of the animals; design of facilities and management, where it is highlighted how when considering the behavior of the animals in the design and management, better results are obtained; social isolation, facilitation, and buffering, where the presence of other members of the group can modify the consumption and sexual behaviors of pen-mates, or even alleviate suffering; and human-animal interaction on productivity, where the relevance of a positive human-animal interaction is highlighted. After reviewing the scientific literature on the subject, we can conclude that several modern livestock management practices might induce stress in animals, affecting their welfare, health, and productive performance. Applied animal behavior could be a sustainable and effective option to understand and solve some of these problems, and in many cases does not even require a strong economic investment for producers.

Ewe-lamb bond of experienced and inexperienced mothers undernourished during gestation

The aims were to compare ewe-lamb behaviours between primiparous (PRI) and multiparous (MUL) undernourished grazing ewes at birth and at 3 months of age, and to determine if mothers’ parity affects milk yield and composition, and lambs’ body weight (BW). Food availability restricted the nutritional requirements from day 30 to day 143 of gestation. The MUL ewes had greater BW than the PRI during gestation, and their lambs tended to vocalize less frequently until their first suckle. PRI ewes both displayed a lower frequency of acceptance behaviours and, a greater number of high-pitched bleats toward the alien lamb than toward that of their own, but MUL did not. PRI ewes produced less milk than the MUL ewes. The heart rate was greater in lambs reared by MUL ewes than by PRI. Although PRI ewes had a lower BW during gestation, this difference was stable throughout and did not affect the establishment of the ewe-lamb bond neither at birth nor at 3 months postpartum. At least under nutritionally restricted conditions during gestation, inexperienced mothers appeared to have had a shorter sensitivity period of maternal responsiveness than that of experienced mothers.

Behavioral and physiological responses to early weaning in ewes and their single or twin lambs

As during the early postpartum, ewes and their twin lambs have a weaker bond than ewes that rear single lambs; it might be expected that early artificial weaning would trigger less intense behavioral and physiological responses in mothers and their twin lambs than in mothers and their single lambs. The aim of this study was to compare the behavioral and physiological responses of ewes and their twin or single lambs to early weaning. The study was performed with 19 Saint Croix ewes: 10 bearing single lambs and nine bearing twins (data from only one sibling from each pair of twins was collected). Lambs were weaned at 43 days old. Body weight, stress-related behaviors, and blood protein concentrations were recorded in ewes and lambs before and after weaning. Single lambs were heavier and paced more frequently during the day of weaning than twin lambs (10.6 ± 0.4 vs 8.9 ± 0.4 kg; P = 0.007 and 4.1 ± 0.4 vs 1.5 ± 0.4%; P = 0.0003, respectively). In addition, ewes rearing single lambs paced and vocalized more than twin lambs' mothers the day of weaning (pacing, 42.4 ± 1.1 vs 20.0 ± 1.2%; P < 0.0001; vocalizations, 43.1 ± 2.6 vs 21.3 ± 2.7%; P < 0.0001). Litter size affected only ewes' albumin concentration, without other effects in protein concentrations in ewes or lambs. In conclusion, early weaning triggered stronger behavioral responses in mothers and their single lamb than in mothers and their twin lambs.

Stress and behavioural responses to winter shearing differ between pregnant and non-pregnant ewes

High progesterone concentrations reduce the stress responses in several mammals. Therefore, it may be expected that pregnant ewes have lower responses to stressors than anoestrous ewes. Our aims were to compare the stress response and the behavioural changes of pregnant and non-pregnant ewes sheared during winter. Two trials were with 20 were pregnant (group PR) and 17 non-pregnant ewes (group NP). In the first trial blood samples were collected immediately before and during the first 180 min after shearing, and cortisol, total protein, and albumin concentrations were measured, and globulin concentrations were calculated. In the second trial, the frequency in which each ewe was observed standing, lying down, walking and grazing were recorded from Day -3 to Day -1 (Day 0 = shearing), from Day 1 to Day 5, on Days 13 and 20-21 during 8 h/day. Scan observations were done every 10 min from 8:00 h to 12:00 h and from 14:00 h to 18:00 h (total = 50 recordings.day). Non-pregnant ewes had greater cortisol concentrations than PR ewes (P = .007). Non-pregnant ewes also had greater total protein concentrations than PR ewes (P = .029). Albumin concentration tended to be greater in NP than PR ewes (P = .064). Globulin concentration 30 min after shearing was greater in PR than in NP ewes (P = .047). Pregnant ewes were observed more frequently standing than NP ewes (P = .013). Non-pregnant ewes were observed more frequently lying down and walking than PR ewes (P = .039 and P = .009, respectively). Before shearing, on Day 2 and Day 4, NP ewes walked more frequently than P ewes (P = .007, P < .0001, P = .007 respectively). Pregnant ewes were observed grazing more frequently than NP ewes (P = .009). Pregnant ewes grazed more than NP ewes on Days 1 and 5 (P = .005 and P < .0001 respectively). Overall, we concluded that shearing was a strong stressor that provoked sustained changes in the behavioural pattern, physiological status and gregariousness intensity despite being or not pregnant. Some responses, as cortisol concentration, changes in the time walking and grazing and the decrease of the cohesiveness after shearing seem to be less pronounced in pregnant than in non-pregnant ewes.

Early mother–young relationship and feeding behaviour of lambs are unaffected by low pasture allowance until the beginning of the last third of gestation in single-bearing ewes

Nutrition during gestation influences ewes’ bodyweight (BW), the bond with their lamb, milk yield and lamb development, and thus feeding behaviour of lambs during postnatal rearing. The aim of this study was to determine if the level of native pasture allowance from before conception until the beginning of the last third of gestation of single-bearing ewes influences the ewe–lamb relationship at birth and the feeding behaviour of lambs during postnatal rearing. A second aim was to determine whether the nutritional treatments affect ewes’ milk yield and their lambs’ bodyweight. Eleven multiparous Corriedale ewes grazed a high pasture allowance [10–12 kg of dry matter (DM)/100 kg of BW/day; HPA treatment], and another 11 grazed a low pasture allowance (5–8 kg of DM/100 kg of BW/day; LPA treatment) for 145 days beginning 40 days before conception. After the end of this treatment all ewes grazed on Festuca arundinacea and received rice bran and crude glycerine until 3 days before birth. Ewes’ BW was recorded monthly before and during gestation. Latency from parturition until the ewe licked her lamb, latency for lamb to stand up and suckle were recorded, and Maternal Behaviour Score was determined 12–24 h after birth. All the variables recorded during postpartum were determined approximately every 30 days. Grazing, ruminating and suckling events of the lambs were recorded from Day 23 until 142 days of age. Milk yield was determined from 32 until 140 days after lambing. Lambs’ BW was recorded from birth until 140 days of age. On Day 41 the BW change tended to be greater in HPA ewes than in LPA ewes, and on Days 79 and 105 it was greater in HPA ewes than LPA ewes (P = 0.006 and P = 0.005 respectively). Treatments did not affect the behaviours at birth of ewes and lambs, milk yield, ruminating and suckling events of lambs, ewes’ and lambs’ BW. The lambs from HPA ewes tended to present a greater frequency of grazing than the LPA lambs. Different levels of native pasture allowances from before conception until the last third of gestation in single-bearing ewes, followed by an increase in nutrient supply, did not affect ewe–lamb behaviours at birth, milk yield, lambs’ growth, and their feeding behaviours during rearing.

Low pasture allowance until late gestation in ewes: behavioural and physiological changes in ewes and lambs from lambing to weaning

Low pasture allowance during gestation affects ewes' BW at parturition, the bond with their lamb, lamb development, and thus also may affect their responses to weaning. The objectives were to determine if native pasture allowance from before conception until late pregnancy affects ewe-lamb behaviours at lambing, ewes' milk yield, lambs' BW, and the behavioural and physiological changes of ewes and lambs at weaning. From 23 days before conception until 122 days of pregnancy, 24 ewes grazed on two different native pasture allowances: high (10 to 12 kg of dry matter (DM)/100 kg of BW per day; HPA treatment; n=12) or low (5 to 8 kg of DM/100 kg of BW per day; LPA treatment; n=12). Thereafter, all ewes grazed on Festuca arundinacea and received rice bran and crude glycerine. Ewes' body condition score (BCS) and BW were recorded during pregnancy and postpartum periods. Milk yield was determined on days 32, 41 and 54 after lambing. Lambs' BW was recorded from birth until 72 days after lambing. Latency from parturition until the ewe licked her lamb, maternal behaviour score (a test that evaluates maternal attachment to the lamb) and latency for lamb to stand up and suckle were determined. The behaviour of the lambs and ewes was recorded before and after weaning (at 65 days). The ewes' serum total protein, albumin and globulin concentrations were measured before and after weaning. The HPA ewes presented greater BW (P<0.005) and BCS (P<0.005) than the LPA ewes during pregnancy and postpartum (P<0.04), and had a greater milk yield than the LPA ewes (P<0.03). Treatments did not influence any behaviour at lambing, lambs' BW, neither the ewes' behavioural and physiological changes at weaning. HPA lambs paced and vocalized more than LPA lambs (P<0.0001). The variation of albumin concentration before and after weaning was greater in the HPA lambs than in the LPA lambs (P<0.0001). In conclusion, although ewes' BW, BCS and milk production were affected by pasture allowance until late pregnancy, this did not affect the behaviours that lead to the establishment of the mother-young bond, nor the ewes' behavioural responses at weaning. Lambs reared by ewes that grazed on low pasture allowance during pregnancy presented fewer behavioural changes and a lower decrease of albumin concentration after weaning. Lambs' BW was not affected by the feeding received by their mothers.