Ewe-reared Lambs Research Articles

The Effect of Artificial Rearing on Live Weight Gain and Bone Morphology of the Tibia in Lambs Prior to Weaning

Growth rates associated with different artificial rearing systems have been thoroughly examined in many species. However, the effect of different rearing systems on bone morphology has not been described. The objective of this study was to examine differences in the bone mass and the relationship of peripheral quantitative computed tomography (pQCT) measures of bone with muscle area of ewe-reared lambs and artificially reared lambs. Lambs were opportunistically collected from a concurrent trial examining changes in ewe mammary glands during lactation. Thirteen lambs were artificially reared while the remaining nine were left on their dam. Measures of stature were taken throughout the six-week trial period. At approximately six weeks of age, the lambs were euthanized and the tibia was collected and scanned using peripheral quantitative computed tomography. Artificially reared lambs had reduced live weight gain and an altered pattern of stature growth. There was no effect of treatment on bone morphology (p > 0.05), but ewe reared lambs had a greater cortical bone content to muscle area ratio than artificially reared lambs (0.06 vs. 0.15, respectively). Differences in growth between ewe reared lambs and artificially reared lambs emphasizes the importance of adequate preweaning nutrition for livestock production systems that routinely use artificial rearing systems.

Effects of rearing system on meat quality, fatty acid and amino acid profiles of Hu lambs.

To determine the effects of early rearing system on meat quality traits, fatty acid and amino acid profiles of meat, 48 Hu lambs were selected and randomly divided into four treatments: control lambs were ewe-reared from birth to 60days of age (ER), while treatment lambs were segregated from their dams at 10, 20 and 30days of age, then artificially reared with milk replacer until 60days of age (EW10, EW20 and EW30, respectively). All lambs had no access to the milk replacer or their dams from 61 to 90days. Creep feed was supplied adlibitum to all lambs from 15 to 90days of age. Artificially reared lambs (EW10, EW20 and EW30) had higher (p<.05) creep feed intake, average daily gain, slaughter weight, hot carcass weight, meat ether extract content, bright meat color (lightness and yellowness) than ewe-reared lambs. The content of unsaturated fatty acids and monounsaturated fatty acids in EW10 and EW20 were greater (p<.05) than that in ER, whereas the proportions of saturated fatty acids in EW10 and EW20 were lower than that in ER (p<.05). The percentages of C18:0, C18:2, C18:3 and the ratio of polyunsaturated fatty acids and saturated fatty acids of artificially reared lambs were greater than ewe-reared lambs (p<.05). The meat proportions of leucine, alanine and proline were higher (p<.05) in artificially reared lambs than ewe-reared ones. Finally, the artificially reared system increased meat production and changed the fatty acid and amino acid profiles of meat, and it would be appropriate to rear Hu lambs artificially from 10 days with milk replacer.

Effects of weaning age on growth, nutrient digestibility and metabolism, and serum parameters in Hu lambs.

This study was conducted to investigate the effect of weaning age on growth performance, nutrient digestion and metabolism, and serological indicators, and to obtain an optimal weaning age in Hu lambs. Forty-eight newborn Hu lambs (birth weight, 2.53 ± 0.14 kg) were randomly divided into 4 groups. The lambs in control group (ER) suckled their dams. The lambs in other three experimental groups were weaned on milk replacer at 10, 20, and 30 days of age (EW10, EW20, and EW30 groups), respectively. The results were as follows: 1) lambs in EW10 and EW30 groups had a lower (P < 0.05) ADG than those in ER group within 10 days post-weaning; the weaned lambs began to show a higher (P < 0.05) ADG than those in ER group after 20 days post-weaning. 2) EW10 and EW20 groups had a higher (P < 0.05) creep feed intake than EW30 and ER groups from 15 to 60 days of age. 3) The apparent digestibility of dry matter, organic matter, gross energy, nitrogen, ether extract and phosphorus, and the deposition of nitrogen and phosphorus did not differ (P > 0.05) among groups; however, the apparent digestibility and deposition of calcium in early weaned lambs were lower (P < 0.05) than those in ewe-reared lambs. 4) The albumin content in EW30 group was lower (P < 0.05) than that in ER group; the globulin content in EW30 group was higher (P < 0.05) than that in other groups; the content of serum insulin-like growth factor-Ⅰ in weaned lambs tended to increase compared with lambs in ER group. Finally, the growth rate of lambs decreased within 10 days post-weaning, but early weaning boosted creep feed intake, leading to better growth and health later in life. The Hu lambs can be weaned on milk replacer and creep feed at 10 days of age.

Effect of rearing system on pre-weaning growth, rumen development and its influence on post-weaning performance of lambs

Abstract. Twenty-four 21-day-old Balouchi male lambs were equally divided into two groups. Twelve subjects were artificially reared (AR), twelve others were ewe reared (ER) and used as control. AR in comparison of ER lambs maintained higher concentrations of blood beta- Hydroxybutyric acid (BHBA); however glucose concentration was not affected by rearing system. Unlike the DNA content and cell size, the RNA concentration and ribosomal capacity (Cs) of AR groups were significantly (P&lt;0.05) higher than that of ER lambs. Rearing system did not affect morphologic characteristics of rumen wall except thickness of keratinized layer that was thickest in AR, 20 % less than in ER lambs (P&lt;0.05). Stomach weight and capacity in AR animals were significantly (P=0.05) higher than ER lambs. Neither post-weaning growth rate nor feed conversion efficiency were affected (P&gt;0.05) by rearing method. Also there were no differences with respect to slaughter and dissection data between groups in postweaning phase. In conclusion, the results of this study showed that naturally rearing system gave rise to developmental and carcass characteristics similar to those observed in artificial raised lambs.

Effect of information about animal welfare, expressed in terms of rearing conditions, on lamb acceptability

The present study was aimed to assess the effect of information about the farming system and welfare of artificially (AR) and ewe-reared lambs (ER) on meat acceptability. An 84-consumer panel was asked to give three types of evaluation for both products: tasting without information (perceived liking); information without tasting (expected liking); tasting with information (actual liking). For both products, the expected liking was significantly different from the perceived liking ( P < 0.001), thus indicating that a disconfirmation occurred. The consumers found ER meat worse than expected (negative disconfirmation) and AR meat better than expected (positive disconfirmation). No significant difference between perceived and actual liking was observed for ER lamb ( P > 0.05), whereas, for the meat produced by AR lambs actual liking was lower than perceived liking ( P < 0.001). However, consumers did not completely assimilate their liking in the direction of expectations, as indicated by the fact that expectancy for AR lamb was significantly lower than actual acceptability ( P < 0.001). Mean scores of perceived liking were higher for the meat produced by AR animals as compared to ER lambs ( P < 0.05). Conversely, expected and actual liking scores were higher for meat from ER lambs than for meat from AR animals ( P < 0.001 and P < 0.05, respectively). These results show that information about animal welfare, expressed in terms of rearing conditions, can be a major determinant of animal-based food acceptability, thus providing a potential tool for meat differentiation.

Influence of gentling on lamb immune response and human–lamb interactions

A 7-week trial was performed to assess the effects of gently handling newborn lambs on their behavioural, immune and endocrine responses, and on their growth rate when mothered or artificially reared. Sixty-four lambs were involved in the study, which were divided in four groups of 16. The ewe-reared lambs (ER and ER + G) were kept with their dams throughout the experimental period. The artificially reared lambs (AR and AR + G) were separated from their dams 24–30 h after parturition, and offered a milk substitute. The ER + G and AR + G animals were subjected to gentling treatment. Behavioural activities of lambs were monitored using scan sampling procedures. Lambs were tested for their responses to two stationary human tests and to isolation in a novel environment. Blood samples were taken from lambs immediately before the isolation test, soon after the test and 60 min after to evaluate their cortisol response. The cell-mediated immune response to PHA and the humoral immune response to KLH were also measured. More AR + G and AR lambs were observed investigating ( P < 0.01) than ER lambs. AR + G treatment also resulted in the lambs most quickly returning to cortisol baseline levels after handling and isolation at 15 days of age ( P = 0.05). No differences in cell-mediated immune response were observed among groups, whereas AR + G lambs displayed antibody titres comparable to groups ER and ER + G, and higher than AR lambs throughout the trial ( P < 0.05). Results suggest that gentling may be properly used in artificial rearing programs of lambs in order to sustain lamb immune function and reduce the risk of disease.

Growth performance of Awassi lambs fed calf milk replacer

Forty Awassi lambs were equally divided into two groups. Twenty subjects were artificially reared (AR) with calf milk replacer, 20 others were ewe reared (ER) and used as a control. Twenty lambs were removed from the ewes 2–3 days postpartum and moved indoors. Lambs (AR) received ad libitum calf milk replacer twice daily until liquid weaning at 4 weeks. At 15 days of age, AR lambs had ad libitum access to commercial lamb starter diet and alfalfa hay while ER lambs continued to suck their mother without any feed supplementation until weaning at 6 weeks. Average daily gain (ADG) and live weights (BW) at 2 weeks intervals were measured. ER lambs were heavier ( P <0.05) than AR lambs at 2 and 4 weeks of age but there were no body weight differences between AR and ER lambs at 6 weeks of age. Litter size had an important effect on birth weight ( P <0.01) and body weight ( P <0.05) at 2 weeks of age. Lamb survival until the 6 weeks of age was 85% for AR lambs and was higher than for ER lambs at 75%. These results show that Awassi lambs can be successfully reared on calf milk replacer at a lower cost than with ewe rearing, thus offers a potential increase in economic returns for sheep producers.

Growth performance of Awassi lambs fed calf milk replacer

Forty Awassi lambs were equally divided into two groups. Twenty subjects were artificially reared (AR) with calf milk replacer, 20 others were ewe reared (ER) and used as a control. Twenty lambs were removed from the ewes 2–3 days postpartum and moved indoors. Lambs (AR) received ad libitum calf milk replacer twice daily until liquid weaning at 4 weeks. At 15 days of age, AR lambs had ad libitum access to commercial lamb starter diet and alfalfa hay while ER lambs continued to suck their mother without any feed supplementation until weaning at 6 weeks. Average daily gain (ADG) and live weights (BW) at 2 weeks intervals were measured. ER lambs were heavier ( P<0.05) than AR lambs at 2 and 4 weeks of age but there were no body weight differences between AR and ER lambs at 6 weeks of age. Litter size had an important effect on birth weight ( P<0.01) and body weight ( P<0.05) at 2 weeks of age. Lamb survival until the 6 weeks of age was 85% for AR lambs and was higher than for ER lambs at 75%. These results show that Awassi lambs can be successfully reared on calf milk replacer at a lower cost than with ewe rearing, thus offers a potential increase in economic returns for sheep producers.

Behaviour and meat production of organically farmed unweaned lambs

Twenty Sarda male lambs, equally divided into two groups, were used to evaluate the effect of artificial rearing on animal behaviour and meat production. Artificially reared lambs showed an altered behavioural pattern with increased suckling attempts ( P<0.001) and levels of social interactions with peers ( P<0.05). In the open field test, they also displayed withdrawal behaviour in terms of reduced time of locomotion ( P<0.05) and increased latency time to the first movement ( P<0.05). Ewe-reared lambs showed a higher growth rate and produced more valuable carcasses. It was concluded that dam-rearing, which is compulsory in organic farming (EU Regulation 1804/1999), can improve carcass quality and affect animal behaviour, which, in turn, is a widely used welfare indicator.

Effect of artificial rearing on lamb welfare and meat quality

Twenty male Comisana lambs were equally divided into two groups. Ten subjects were artificially reared, 10 others were ewe reared and used as control. Unseparated control animals displayed increased cellular immune response to a percutaneous injection of phytohemagglutinin ( P<0.001). During the open field test, ewe-reared lambs showed a higher number of flight attempts ( P<0.01). Carcass yield were higher for artificially reared animals ( P<0.05). Conversely, legs of ewe-reared animals had significantly more fat ( P<0.05) and a higher content of saturated fatty acids ( P<0.001). Polyunsaturated fatty acid content was higher in artificially reared lamb meat ( P<0.01), although the ratio n-6/n-3 was well above the recommended values. The triangle test showed a significant difference in sensory analysis between the two products ( P<0.05 ). Finally, for both rearing systems legs without subcutaneous fat showed a higher percentage of polyunsaturated fatty acids and a corresponding lower content of saturated fatty acids ( P<0.001).

Adipose tissue development during early postnatal life in ewe‐reared lambs

This study examines the precise time course that brown adipose tissue (BAT) takes to adopt the characteristics of white adipose tissue in postnatal lambs. Perirenal adipose tissue was sampled from ewe-reared lambs within 1 h of birth and at 1, 2, 4, 7, 14, 21 and 30 days of age and analysed for the amount of mRNA for uncoupling protein (UCP), the amount and activity of UCP, and protein, mitochondrial protein and lipid content. This was combined with measurements of colonic temperature and jugular venous plasma concentrations of thyroid hormones and insulin-like growth factor-1 (IGF-1). Over the first 4-7 days of age, large quantities of UCP mRNA were associated with a peak in plasma triiodothyronine concentration at 2 days of age followed by a maximal amount and activity of UCP at 4 days and a basal colonic temperature of 39.3 degrees C. Between 7 and 30 days there was a large increase in lipid deposition as the amount and activity of UCP and the amount of UCP mRNA declined to basal values and colonic temperature was maintained at 40 degrees C. A significant positive relationship between perirenal adipose tissue lipid content and plasma IGF-1 concentration was observed throughout the study period. It is concluded that ovine adipose tissue maturation occurs in two distinct phases over the first month of life. The precise time scale of this process could be regulated in part by the lamb's body temperature which determines whether adipose tissue is required for heat production (i.e. BAT) or as an endogenous energy source (i.e. white adipose tissue).

Brown adipose tissue and liver development during early postnatal life in hand-reared and ewe-reared lambs

This study examined the effects of modest changes in ambient temperature in hand-reared lambs (experiment one) and in ewe-reared lambs (experiment two). Lambs were killed at either 8 or 31 days of age and perirenal adipose tissue was identified as being brown adipose tissue (BAT) from measurements of thermogenic activity (i.e. GDP binding to uncoupling protein in isolated mitochondria) or thermogenic capacity (i.e. detection of uncoupling protein by immunoblotting). In addition, type I and II iodothyronine 5' monodeiodonase (5'MDI) activities were assayed in perirenal adipose tissue, plus type I 5'MDI activity in liver. Plasma samples were also taken for measurements of glucose, lactate, insulin, triiodothyronine (T3) and thyroxine (T4) concentrations. In experiment one, lambs were hand-reared at either warm (WR; 25 degrees C) or cool (CR; 10-15 degrees C) ambient temperatures. Mean growth rate over the first 8 days of life in CR lambs was 88 g/day and increased to 128 g/day over the first month of life. Growth rate in WR lambs was constant at 141 g/day. Thermogenic activity of BAT was significantly higher in CR than WR lambs, but total weight and tissue lipid content of perirenal adipose tissue were significantly lower in the CR group. In both WR and CR lambs, the thermogenic activity of BAT fell by an average of 71% between 8 and 31 days. At 31 days of age, uncoupling protein in mitochondria could be detected only by immunoblotting in adipose tissue sampled from CR lambs. There was no effect of ambient temperature on type I or type II 5'MDI activity in BAT or liver; it decreased in adipose but not liver tissue between 8 and 31 days of age. The plasma concentrations of glucose, insulin and T3 tended to decline with age in CR but not in WR lambs. In ewe-reared lambs perirenal adipose tissue weight and tissue lipid content more than doubled between 8 and 31 days of age, but the level of GDP binding decreased from 85 to 5 pmol/mg mitochondrial protein over this period. Liver weight increased by 55% between 8 and 31 days of age, but hepatic 5'MDI activity remained unchanged. The plasma concentrations of T3, T4 and lactate, but not glucose or insulin, increased between 8 and 31 days of age. It is concluded that hand-rearing lambs at a cool ambient temperature significantly delays postnatal development, to the extent that BAT characteristics are retained. Ewe-rearing lambs enhances the rate at which BAT adopts the characteristics of white adipose tissue, and it prevents the postnatal decline in plasma concentrations of thyroid hormones.

Training Lambs to Be Weed Eaters: Studies with Leafy Spurge

The objective of the study was to determine if exposure of young lambs to leafy spurge (Euphorbia esula L.) would increase the consumption of this plant. Orphan lambs were exposed to leafy spurge from birth to 11 weeks of age as a water soluble extract mixed with milk replacer and as freshly harvested plants. Ewe-reared lambs were exposed to leafy spurge by grazing them on a leafy spurge-infested pasture. Study 1 investigated the consumption of vegetative and flowering leafy spurge paired with arrowleaf balsam root (Balsamorhiza sagittata (Pursh)Nutt.) by orphan lambs during a 30-min feeding period. Experienced lambs consumed a higher percentage leafy spurge than naive lambs (P 0.23) by previous exposure, but daily herbage removal was greater (P<0.09) in pastures grazed by experienced compared to naive lambs (876 vs. 685 g/lamb, respectively). Experienced ewe-reared lambs had a higher rate of biting on leafy spurge (P<0.06) than naive or orphan lambs. These studies indicate that previous experience will be an important factor affecting the use of sheep as a biological control agent for leafy spurge.

Differential vulnerability of lambs to coyote predation

Coyote-lamb interactions in 65-ha pastures were observed during a study of Komondor dogs guarding sheep. Vulnerability of lambs to coyote predation was related to total time lambs were exposed to coyotes in the enclosures and total time present in the flock. Lambs were most vulnerable during the first two weeks of exposure ( P < 0.001, X 2 = 49.3), and were somewhat less vulnerable in the next 4 weeks of exposure. If the lambs survived 6 weeks of exposure, their chances of succumbing to predation were small. Lambs were most vulnerable if they were added to an established flock. Orphan lambs were more vulnerable than ewe-reared lambs. Even though the coyotes in this study were persistent in attacking lambs, their success was limited for at least 3 reasons. First, the lambs sometimes refused to run from the coyotes. In addition, they occasionally actively defended themselves by foot-stomping, butting and approaching the coyote. Finally, no lambs were killed while in close proximity to a guardian dog. Based on this study, predation might best be reduced by minimizing introductions of new lambs, and especially orphan lambs, to established flocks, and by using a guardian dog, if possible.