Aspects of neonatal physiology have an influence on lambs’ early growth and survival in prolific D’man sheep

The curse of the firstborn: Effects of dam primiparity on developmental programming in ruminant offspring

The first parity, or first pregnancy, of ruminant females has negative effects on offspring during fetal, perinatal, and pre-weaning periods which ultimately lead to diminished pre-weaning productivity. Offspring born to primiparous ruminant females can have decreased fetal and pre-weaning growth, resulting in lower body weights at birth and weaning in cattle, sheep, and goats. Moreover, mortality is greater during both neonatal and pre-weaning periods. Insults during these critical developmental windows likely also have long-term consequences on first-parity offspring through developmental programming, but less research has been done to investigate effects in the post-weaning period. Many potential physiological, metabolic, and behavioral mechanisms exist for the outcomes of dam primiparity. Although competition for nutrient partitioning between maternal and fetal growth or lactation is often cited as a major contributor, we hypothesize that the most important mechanism causing most first-parity outcomes is the relative physiological inexperience of reproductive tissues such as the uterus and mammary gland during the first pregnancy and lactation, or a "first use theory" of tissues. More research is necessary to explore these areas, as well as if primiparous dams respond differently to stressors than multiparous dams, and if stress during the first parity affects subsequent parities.

Metabolic adjustments in neonatal dwarf and normal-sized goat kids: Relationship between serum metabolites and body size

The relationship between body size and metabolism of goats remains poorly studied. The study evaluated the neonatal metabolic adjustments and elucidated the relationship between serum metabolites and body size in 39 single-born dwarf and normal-sized goat kids. Body weight, length and height of kids were recorded at birth and blood samples were collected from the dwarf and normal-sized (Red Sokoto and Sahel) goats on Days 0 (birth), 3, 10 and 20, postnatal. Also, the body mass index (BMI) was calculated and the concentration of metabolic markers was determined. Results revealed that values of BMI, body weight, length and height were lowest (P < 0.01) in the dwarf, followed by values in Red Sokoto kids, while the Sahel kids had the highest (P < 0.01) values. Conversely, the concentration of triglyceride at birth was highest (P < 0.05) in the dwarf, moderate in Red Sokoto and lowest in Sahel goats. Similarly, the Sahel goat kids had the lowest neonatal (P < 0.05) concentration of serum cholesterol. Neonatal concentrations of serum albumin and urea were higher in Sahel than Red Sokoto (P < 0.05) and the dwarf (P > 0.05) goats. Concentration of serum albumin was lower (P < 0.05) at birth, but significantly increased later, while values of serum urea concentration were higher (P < 0.05) at birth, but significantly decreased in subsequent postnatal days. Unlike the BMI, birth weight showed significant negative (P < 0.05) correlation with the concentration of most serum metabolites, especially triglyceride, which showed negative correlation at birth and in subsequent postnatal days. We concluded that dwarfism or small body size is associated with high serum triglyceride in single-born neonatal goats, and this is probably due to the accumulation of body energy reserve in the form of body fat to compensate for lower body tissue mass.

Effects of spring- versus fall-calving on perinatal nutrient availability and neonatal vigor in beef cattle

To determine the effect of calving season on perinatal nutrient availability and neonatal beef calf vigor, data were collected from 4 spring- (average calving date: February 14; n = 203 total) and 4 fall- (average calving date: September 20; n = 179 total) calving experiments. Time to stand was determined as minutes from birth to standing for 5 s. After birth, calf weight and size (length, heart and abdominal girth, and cannon circumference) were recorded. Jugular blood samples and rectal temperatures were obtained at 0, 6, 12, and 24 h postnatally in 6 experiments and at 48 h postnatally in Exp. 2 to 8. Data were analyzed with fixed effects of season (single point) or season, hour, and their interaction (over time, using repeated measures). Experiment was a random effect; calf sex was included when P ≤ 0.25. Within calving season, correlations were determined between calf size, vigor, and 48-h serum total protein. Fall-born calves tended to have lighter (P = 0.09) birth weight and faster (P = 0.05) time to stand than spring-born calves. Season did not affect (P ≥ 0.18) gestation length, other calf size measures, or 48-h serum total protein. Fall-born calves had greater (P ≤ 0.003) rectal temperature at 0, 24, and 48 h postnatal. Spring-born calves had greater (P ≤ 0.009) circulating glucose at 0 h, serum non-esterified fatty acids at 0 and 6 h, and plasma triglycerides at 0, 6, 12, and 48 h. Fall-born calves had greater (P ≤ 0.03) sodium from 6 to 48 h and magnesium from 0 to 24 h of age. Phosphorus was greater (P ≤ 0.02) at 6 and 12 h of age in spring-born calves. Spring-born calves had greater (P ≤ 0.04) aspartate aminotransferase at 12 and 24 h and creatine kinase at 0 and 12 h of age. Fall-born calves had greater (P ≤ 0.03) albumin, calcium, and chloride, had lower (P ≤ 0.03) bicarbonate and direct bilirubin, and tended to have greater (P = 0.10) anion gap (all main effects of calving season). Calf birth weight had a weak positive relationship (P ≤ 0.03) with 48-h serum total protein and time to stand in fall-born, but not spring-born, calves. Overall, fetal growth was restricted and neonatal dehydration was increased by warm conditions for fall-born calves, but vigor and metabolism were negatively affected by cold conditions in spring-born calves. These data suggest that calving season influences perinatal nutrient availability, which may impact the transition of beef calves to postnatal life.

Postnatal hypoglycemia and blood glucose concentrations in neonatal tropical goat kids

This study aimed to evaluate the influences of breed, sex, litter size, and birth weight on the incidence of postnatal hypoglycemia and blood glucose concentrations in neonatal tropical goats. A total of 160 neonatal goat kids belonging to Red Sokoto (n = 98), Sahel (n = 40), and West African Dwarf (n = 22) breeds, were categorized after birth based on glycemic status, sex, litter size, and birth weights (high or low). Blood samples were collected on postnatal days 0, 1, 2, 3, 10, and 20 to determine blood glucose concentrations. Results revealed that the incidence of hypoglycemia at birth among neonatal goat kids was 22.5% (36/160) and was significantly (P < 0.05) higher in the Sahel breed kids, twin kids, and kids born with low birth weights. After 24 hours, all hypoglycemic kids became normoglycemic but maintained lower (P < 0.05) blood glucose levels than those that were normoglycemic at birth, until day 10, when both groups had comparable blood glucose levels. In all groups, blood glucose concentrations increased significantly 24 hours postnatal, and kids with high birth weights had significantly higher values than those with low birth weights, while the buck kids had higher values than the doelings. There was a negative correlation (r = -0.31; P < 0.0003) between the blood glucose concentration of dams and those of their kids. In conclusion, the incidence of hypoglycemia in tropical goat kids was markedly influenced by breed, birth weight, and litter size. Furthermore, the hypoglycemic kids maintained lower blood glucose concentrations until day 10 postnatal, suggesting the need for relevant nutritional provisions for hypoglycemic kids during this critical period.

Does lambing season affect mother-young relationships and lamb vigor in D'man sheep reared in oases?

Although sheep are known to be seasonal breeders and give birth in winter, not all of them follow this trend. A few breeds can be mated and give birth all year round, meaning that mothers and neonates will have to face contrasting climatic conditions. The aim of this study was to test whether lambing season affects maternal and neonatal behaviors in D'man sheep. During four different lambing seasons (winter, autumn, summer and spring), periparturient ewes (n = 111) and their lambs (n = 213) were kept under 24-h-video surveillance in order to record postpartum behaviors. Mother-young preference was tested around 48 h after parturition. Lamb vigor was studied by the determination of birth weight, early postnatal behavior and rectal temperature at birth and 48 h later. Litter expulsion time was not affected by lambing season, but birth weight was biased against summer and winter born lambs. Ewes provided a higher intensity of care to their offspring in winter: latency for grooming was shorter and time spent grooming was longer compared to lambing in spring and summer (P = 0.01 in all cases). On the other hand, lambs were the most active in spring as they were faster to extend their hind legs (P = 0.01), stand up (P = 0.04) and reach the udder (P = 0.04). Rectal temperature at 48 h was affected by season of birth (P < 0.001) with higher values observed in summer. Glycemia variation between birth and 48 h was the lowest in spring born lambs and plasma levels increased less in spring born lambs than in winter (P < 0.0001), autumn (P < 0.0001) and summer born lambs (P < 0.0001). In the choice test, mothers clearly preferred their own young and no season effect was detected except that in the first minute of the test they spent less time near their own young in winter than in the other seasons (P = 0.04). Lambs also chose their mother successfully without any major effect of the season however, but winter born lambs were the least vocal (P = 0.01). Overall, this study show that maternal care, lamb behavior and vigor vary lightly according to seasons, albeit not in a consistent manner. In conclusion, a season is no more detrimental than another for the onset of mother-young relationships.

Production performance of sheep and goat breeds at a farm in a semi-arid region of Namibia

This study retrospectively investigated the effect of breed and season on the lambing/kidding dynamics, growth performance, neonatal viability, and weaning dynamics of sheep (Damara, Dorper, and Swakara) and goats (Boer goat and Kalahari Red) at a farm in the Khomas Region of Namibia between 2004 and 2015. Litter size was dependent on breed (X²(12, N = 3388) = 796, p < 0.001), with twinning more frequent in Dorper sheep and Kalahari Red and Boer goats than in the Damara and Swakara sheep (p < 0.05), while triplets were more prevalent in the Dorper sheep and Kalahari Red goats (2.8% and 1.0%, respectively; p < 0.05). Distribution of birth weight categories was dependent on breed. There was a significant difference in the proportions of birth weight categories between breeds (X²(12, N = 3388) = 467, p < 0.001) whereby Dorper lambs were mostly born weighing below 3 kg (2.6%, p < 0.05); Boer goat kids, Kalahari Red kids, and Damara lambs were mostly born weighing 3 to < 4 kg (4.3%, 6.3% and 19.9%, respectively; p < 0.05); Swakara lambs were mostly born weighing 4 to < 5 kg (12.2%, p < 0.05), and Swakara lambs were mostly born weighing ≥ 5 kg (3.3% and 2.3%, respectively, p < 0.05). Weaning age categories were dependent on breed (X²(12, N = 3388) = 241, p < 0.001) whereby Dorper lambs were mostly weaned at below 3 months of age (2.8%, p < 0.05); Damara lambs were mostly weaned at 3 to < 5 months of age (12%, p < 0.05), and Boer goat kids were mostly weaned at ≥ 5 months of age (0.9%, p < 0.05). Neonatal viability was dependent on breed (X²(8, N = 3388) = 49.2, p < 0.001) whereby Dorper lambs were more susceptible to abortions and neonatal deaths (0.6% and 1.5%, respectively; p < 0.05) than the rest of the breeds. Breed and lambing season interacted to produce effects on the birth weight of offspring although lambing season alone did not have a significant effect on Boer goat and Kalahari Red kids' birth weights.

Factors affecting the milk yield and composition over lactation of prolific D'man ewes in Tunisian oases

This work aimed to investigate milk potentiality and the influence of some non-genetic factors both on milk yield production and composition in prolific D'man sheep. Observations were performed in eighty lactating D'man ewes maintained under an intensive oases system in Southern Tunisia. Daily milk yield was determined at 7-day intervals using oxytocin + hand milking method. Chemical milk composition was determined by Lactoscan. Total productions over lactation (milk, fat, and protein) were estimated using the Fleischmann method. Daily milk yield averaged 1.64 ± 0.02 l. It increased to a plateau from the third to the fourth week of lactation, and decreased gradually to the tenth week. D'man ewes produced 128.91 ± 3.14 l of milk, 9.23 ± 0.26 kg of fat, and 5.26 ± 0.12 kg of total proteins. Overall, milk contained 16.17% of total solids, 7.08% of fat, 4.04% of proteins, 4.32% of lactose, 9.09% of solids-not-fat, and 0.73% of ash. Lambing season affected the daily milk yield and milk composition, where fat and total proteins were highest in autumn. Total solids, lactose, solids-not-fat, and ash were higher in winter than in autumn and summer. Ewes reared multiple lambs produced more milk than those reared singles. Dams nursing triplets or more had the highest milk total proteins, and the lowest total solids and fat levels. Adult ewes produced more milk compared to younger and older ewes, and their milk contained higher total solids, fat, and ash levels than milk from young ewes. Ewes with asymmetric udder produced less and more concentrated milk than ewes with symmetrical udder. Daily milk yield was negatively correlated to total solids, fat, and total proteins amounts. In contrast, litter survival at weaning was positively correlated to the amounts of total milk, fat, and total proteins.

Physiological differences between twin and single-born lambs and kids during the first month of life

Abstract. The effects of time after birth and of twinning on rectal temperature (RT), heart rate (HR), respiratory rate (RR) and body weight (BW) values were evaluated in five singleton Comisana lambs (three males and two females), five singleton Maltese Kids (three males and two females), four couples of twin Comisana lambs (four males and four females) and four couples of twin Maltese kids (four males and four females) during the first month of life. For all kids and lambs, RT, HR, RR and BW were recorded after 1 and 24 h from birth and every 2 days until the 30th day of life. The application of two-way repeated measures analysis of variance (ANOVA) showed a statistically significant effect of time (P < 0.0001) on RT, HR, RR and BW values in all lambs and kids during the first month of life. Any significant effect of twinning (P > 0.05) on all studied parameters was found in lambs, whereas statistically significant differences in BW, RT and HR values (P < 0.01) were found between twin and singleton kids throughout the first month of life. The results obtained in this study make a contribution to the knowledge of homeostatic, cardiorespiratory and thermoregulatory adaptations occurring in singleton lambs and kids and in twin lambs and kids during the first 30 days of life. Our findings indicate that the BW, RT, HR and RR values, whose homeostasis is still evolving in newborn, should be interpreted dynamically as a function of the period of postnatal adaptation and also of twinning.

Supplementation of Merino ewes with cholecalciferol in late pregnancy improves the vitamin D status of ewes and lambs at birth but is not correlated with an improvement in immune function in lambs

Functional deficiencies of the immune system are known to predispose human and animal neonates to death. Thus, immune competency may be a significant factor influencing the mortality of lambs. Vitamin D has been recognised to improve immune function and is transferred across the placenta. This study tested the hypotheses that (1) supplementation of Merino ewes with cholecalciferol during late pregnancy will increase the concentrations of vitamin D in the ewe and lamb at birth and (2) supplementation of Merino ewes with cholecalciferol during late pregnancy is correlated with an increase in innate phagocytic and adaptive antibody immune responses in the lamb. Merino ewes (n = 53) were injected intramuscularly with 1 × 106 IU cholecalciferol at Days 113 and 141 of pregnancy. A control group (n = 58) consisted of ewes receiving no additional nutritional treatments. The vitamin D status of ewes and lambs was assessed up until 1 month post-lambing. Lamb immune function was assessed by analysing the functional capacity of phagocytes, and the plasma IgG and anti-tetanus-toxoid antibody concentrations between birth and weaning. Maternal supplementation with cholecalciferol increased the plasma 25(OH)D concentrations of both ewes (137 vs 79 nmol/L; P < 0.001) and lambs (49 vs 24 nmol/L; P < 0.001) at birth compared with the controls. Supplementation with cholecalciferol had no significant effect on the phagocytic capacity of monocytes or polymorphonuclear leukocytes, the concentration of IgG in the colostrum or plasma of lambs, or the vaccine-specific antibody response against tetanus toxoid. Overall, the results support our first hypothesis, but suggest that maternal supplementation with 1 × 106 IU cholecalciferol does not improve innate, passive or adaptive immune function in lambs.

Physiological changes in the peri-partum period and colostral IgG transfer in prolific D'man sheep: effects of parity and litter size

The aim of this work was to assess maternal and neonatal changes in plasma proteins, glucose and cortisol and to quantify the colostral immunoglobulin G (IgG) transfer in the peri-partum period in D'man sheep, a prolific breed, taking into account the parity of the ewe. The concentrations of proteins and glucose were high in the ewes on day 7 and at lambing before decreasing. Likewise, cortisol plasma concentration was maximal during the 6 h following lambing and dropped at 12 h. Protein and glucose concentrations were low in lambs at 1 h of birth after which they increased. By contrast, cortisol level was the highest during the first 12 h of birth and then decreased. The colostral IgG level was high at lambing and dropped by over 87 % from 1 to 48 h post-partum. In the newborn, the plasma IgG concentration was lowest at birth and increased rapidly during the first 24 h of birth. Parity influenced maternal physiology with multiparous ewes having the lowest concentrations of proteins, glucose, IgG and cortisol, but the highest colostrum IgG level. Accordingly, lambs born from primiparous ewes had lower protein, glucose and plasma IgG concentrations than lambs born from multiparous ewes. The main outcome of this study was that lambs born from primiparous ewes are characterized by the lowest physiological indices and this may influence their survival chance.

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.