Effects of feeding system on carcass and non-carcass composition of Churra Tensina light lambs

Thirty-eight single male lambs (3.6 ± 0.08 kg live weight at birth) were used to study the influence of feeding system on carcass and non-carcass composition of Churra Tensina light lambs. Treatments: indoor (IND), lambs housed indoors consuming concentrate ad libitum until weaning at 53 days of age, and ewes grazing 8 h a day without their offspring and receiving a supplement of barley meal after grazing; grazing (GR), ewes and lambs grazed continuously without concentrate and lambs were unweaned. When lambs reached 22–24 kg live weight they were slaughtered. Carcass and non-carcass composition was recorded. GR lambs displayed higher carcass shrink (P < 0.05) and lower dressing percentage (P < 0.01) than concentrate-fed lambs. IND lambs had more body fat mainly due to the heavier kidney (P < 0.001) and subcutaneous (P < 0.001) fat depots. Total non-carcass weight was not affected by treatment (P > 0.05), but red organ (heart, lung and trachea, thymus, liver, spleen, kidney, diaphragm, pancreas, gall bladder, bladder, and testicles and penis), digestive tract (stomach, small intestine and large intestine) and head, skin, and feet (HSF) weights differed between treatments (P < 0.05). IND lambs had heavier red organs and HSF (P < 0.05) although this difference disappeared when expressed as a percentage of empty body weight. Small intestine weight in grazing lambs was heavier (P < 0.001) and, consequently, the total digestive tract differed similarly (P < 0.01). Treatment influenced the weights (P < 0.05) of all joints except leg (P > 0.05), showing heavier joints for IND carcasses. The feeding system had a greater effect on subcutaneous fat (P < 0.001) than on intermuscular fat (P < 0.05) in most of the standardized joints. IND carcasses produced a greater proportion of muscle/bone in all joints, except neck, whereas GR produced a greater proportion of muscle/total fat due to the lower amount of fat recorded in this treatment. The percentage of fatty acids was not affected by treatment (P > 0.05) although the percentage of C18:3 was greater and the ratio of C18:2/C18:3 was lower in grazing-fed lambs. The absence of any effect of treatment on the fatty acid percentages may be influenced by the short raising period and by the similar amount of intramuscular fat in both treatments. It is concluded that light lambs reared under grazing conditions can produce carcasses of acceptable quality, due to the lower percentage of subcutaneous fat, but with a similar intramuscular fat content.     

Efficacy of marbofloxacin against respiratory infections of lambs

The trial was carried out in a sheep flock with mixed Mannheimia haemolytica/Mycoplasma spp. respiratory infection; 60 lambs were included therein and allocated as follows: lambs in group MH were subcutaneously injected with marbofloxacin (3.0 mg/kg bodyweight) on two occasions, once daily 2 days apart – lambs in group ML3 were given marbofloxacin (2.0 mg/kg) on three occasion, once daily for three consecutive days – lambs in group ML2 were given marbofloxacin (2.0 mg/kg) on two occasions, 2 days apart – lambs in group T were subcutaneously injected with tilmicosin (15 mg/kg) on two occasions, 4 days apart – lambs in group C were untreated controls. The lambs were monitored before and after treatment and the clinical findings were scored; they were euthanatised 42 days after treatment for pathological examination of the lungs. Groups were similar at the start of a field trial with respect to all parameters (general clinical condition, presence of nasal discharge, presence of ophthalmic discharge, results of lung auscultation) evaluated (P > 0.05). After treatment, no systemic or local adverse reactions were observed in any lamb. Forty-two days after treatment, the median general clinical assessment score of groups MH, ML3 and T was 0, that of group ML2 was 1 and that of group C lambs was 2 (P < 0.01). Treatment with marbofloxacin was associated with improved clinical scores; the results were similar for all evaluations 14 days after treatment and subsequently. Clinical cure rate 42 days after treatment was 100, 100, 42, 100 and 0% for group MH, ML3, ML2, T and C lambs, respectively (P < 0.01). After controlling for initial weight, treatment was found to have a significant effect on carcass weight (P < 0.01). Pairwise differences in lung lesion scores between any of the four treated groups and the untreated controls were significant (P < 0.02). It is concluded that marbofloxacin is effective against respiratory infections of lambs at a dose rate of 3.0 mg/kg bodyweight given on two occasions, once daily 2 days apart or at a dose rate of 2.0 mg/kg given on three occasions for three consecutive days.     

Effect of barley and oats on feed intake,live weight gain and some carcass characteristics of fattening lambs

The influence of whole, crushed and ground barley and oats on intake, performance and carcass characteristics of lambs was examined. A comparison of diets was conducted with individually-fed male and female lambs in six groups. The study was repeated in three successive years (1995–1997) using the same experimental design. A total of 192 lambs of a mean initial age of 74 days (SD 13.0) and live weight 20.6 kg (SD 4.54) were daily fed their respective concentrates, 72 g dry matter (DM)/kg metabolic live weight (kgW^0.75), for 98 days from weaning to slaughter. Hay was provided ad libitum.The lambs adapted more quickly to diets containing barley than to those containing oats. Compared to oats, the total daily DM intake was higher on barley (1162 vs. 990 g DM/lamb, 89 vs. 78 g DM/kgW^0.75, P < 0.001). Hay consumption was significantly lower on oats than on barley (182 vs. 344 g DM/day, P < 0.001). On oats the lambs experienced energy and protein deficiencies with their energy and protein intakes being 20% below feeding recommendations. On the barley diets the energy and protein requirements of the lambs were satisfied. When processed cereals were offered, there was no increase in the total DM, energy or protein intakes. Processing did not improve the organic matter digestibility of barley or oats.The growth rate (P < 0.01), carcass weight (P < 0.001) and slaughter percentage (P < 0.001) were higher on a barley diet than on oats. A barley diet resulted in more kidney fat (P < 0.01) and fattier carcasses. Processing had no positive influence on the live weight gain. On the contrary, lambs receiving crushed or ground barley or oats had a lower final live weight than those receiving whole grains (P < 0.001). The utilisation of whole grain was more efficient than that of processed grain. There were no advantages in processing barley and oats for the feeding of lambs.     

Fatty acid profiles,growth, and immune responses of neonatal lambs fed milk replacer and supplemented with fish oil or safflower oil

Diets supplemented with long chain, n − 3 polyunsaturated fatty acids (PUFA) have improved the health and performance of neonatal and growing animals. This study was conducted with lambs that were orphaned at approximately 1 day of age to determine whether supplementing milk replacer fed lambs with oils rich in long chain n − 3 or n − 6 PUFA would alter plasma lipid profiles and affect growth characteristics and immune functions. From days 1 to 28 of age, lambs had ad libitum access to commercial milk replacer. From days 7 to 28 of age, lambs received twice daily either 1 g of soybean oil, 1 g of fish oil, or 1 g of safflower oil per os in a gelatin capsule (n = 60 pens; 20 pens/treatment; one ewe and one ram with similar initial body weights/pen). On days 7, 14, 21, and 28 of age, lambs were weighed, and jugular blood was collected from ram lambs. Lymphocyte proliferation in vitro, differential white blood cell (WBC) counts, and weight gains were quantified. Plasma from days 7 and 28 was used for fatty acid analyses. Fish oil increased (P < 0.001) plasma total n − 3 fatty acid concentration and total n − 3:total n − 6 fatty acid ratio. Pen body weight (i.e., total lamb weight per pen) increased (P < 0.001) with day (day 7, 11.9 kg; day 14, 15.1 kg; day 21, 18.2 kg; and day 28, 21.2 kg), but oil treatment did not affect pen body weight. Neither oil treatment, day, nor oil treatment × day interaction were significant for pen body weight gains (3.5 kg), pen average daily gains (0.5 kg), pen milk intakes (19.0 kg), or pen gain:feed ratio (0.18) measured during three intervals: days 7–14; days 14–21; and days 21–28. Day, but not oil treatment, affected (P < 0.001) unstimulated, concanavalin A stimulated, and lipopolysaccharides stimulated lymphocyte proliferation: days 14, 21, and 28 proliferation > day 7 proliferation. For neutrophils per 100 WBC, the treatment × day interaction was significant (P < 0.05). Oil treatment and day affected (P < 0.01 and <0.05, respectively) lymphocyte numbers per 100 WBC. For monocytes, eosinophils, and basophils, neither oil treatment, day, nor the oil treatment × day interaction were significant. Fish oil altered plasma fatty acid profiles, but it did not seem to improve measures of the performance or immune function of healthy, milk replacer fed lambs.     

Production efficiency and feeding behavior of Awassi lambs and Baladi kids fed on a high concentrate diet

Fifteen Awassi lambs and 15 Baladi kids (males, averaging 14.3 kg) were used to study the differences in feeding behavior and performance of sheep and goats fed a concentrate finishing diet (CP = 16 kg/100 kg DM, ME = 2.85 Mcal/kg DM) in a complete randomized design experiment lasting 60 days. Dry matter (DM) and organic matter (OM) intakes were significantly (P < 0.05) higher in lambs. Kids had higher (P < 0.05) apparent OM, crude protein (CP) and gross energy digestibilities. No significant (P > 0.05) differences were observed in apparent neutral detergent fiber (NDF) digestibility, eating, chewing and ruminating times. However, eating and ruminating times (as min/kg NDF intake) was significantly (P < 0.05) higher in kids. Final body weight and average daily weight gain were significantly (P < 0.05) higher in lambs while kids had significantly (P < 0.05) lower feed to gain ratio. Feed cost per kilogram weight gain for kids was better than that for lambs. Results demonstrated that Awassi lambs consumed more feed and grew faster than Baladi kids. However, kids were more efficient feed converters than lambs.     

Factors associated with lamb mortalities in Muzaffarnagari sheep

The Muzaffarnagari sheep, a mutton-producing breed of India, is generally known for its fast growth rate and high feed conversion efficiency. The study identified the causes of perinatal and postnatal deaths and factors contributing to the cause of mortalities in lambs. Data were recorded for 4628 lambs born to Muzaffarnagari ewes in single-sire matings from 165 rams, between 1978 and 2002. The least-squares means for overall lamb mortality from birth to 1 year of age in the flock was 12.6% (582/4628), while the overall pre- and post-weaning mortality rate averaged 6.6% and 6.0%, respectively. The mortality rate of the lambs declined as the lambs grew older. The major causes associated with lamb losses were pneumonia (31.4%), digestive disorders (14.6%), starvation (9.6%), endoparasitism (5.0%), septicaemia and toxaemia (10.1%), accidental (2.1%) and undetermined causes (27.2%), respectively. The main causes of early lamb mortality (within 15 days of birth) were pneumonia followed by starvation. The highest lamb mortalities occurred within the first 15 days of life. The year of birth of the lamb significantly affected (P < 0.01) the cumulative lamb mortality rate at all ages. The sire of the lamb also had a significant (P < 0.01) effect on lamb mortality rate at all ages. Lambs reared under an intensive feeding management system had a remarkably (P < 0.01) lower mortality rate than lambs maintained under a semi-intensive management system, at 3 months of age and later. The lamb losses were significantly (P < 0.01) higher in ram lambs than in females during the post-weaning stages. The linear regressions of lamb birth weight and dam weight at lambing were highly significant (P < 0.01) with lamb mortality rate during pre- and post-weaning stages. Logistic regression analyses revealed lambs maintained under a semi-intensive system, to be at a greater risk of dying from all ailments than lambs maintained under intensive feeding systems. Male lambs had greater risk of death from respiratory, digestive and other causes, compared to their female counterparts. The findings of this study revealed causes of pre-weaning lamb mortalities to be mainly due to a low birth weight and non-parasitic diseases (predominantly pneumonia). These factors must be considered in any lamb production system.     

Growth performance and carcass traits of forage-fed hair sheep wethers

The objective of the present study was to compare live animal performance and carcass characteristics of 3/4 or 7/8 Dorper (DO; n = 30), purebred Katahdin (KA; n = 20), purebred St. Croix (SC; n = 17) and purebred Suffolk (SU; n = 10) lambs born in the spring and fall of 2001. After weaning, lambs were supplemented with up to 680 g of a corn-soybean meal supplement while grazing bermudagrass pastures overseeded with ryegrass. Lambs were slaughtered at approximately 210 d of age. From birth to weaning, DO lambs gained faster (P < 0.001) than KA or SC lambs, whereas KA lambs had higher (P < 0.001) ADG than SC lambs. Additionally, DO and SU wethers had greater (P < 0.02) ADG from weaning to slaughter than SC or KA wethers. Suffolk lambs were heavier (P < 0.001) at slaughter and produced heavier (P < 0.001) carcasses than lambs from hair-sheep breeds. Carcasses of KA lambs were fatter (actual fat thickness; P < 0.02) resulting in higher yield grades (P < 0.03) than carcasses of DO, SC, or SU lambs. Carcasses of DO and SU had larger (P < 0.001) longissimus muscle (LM) areas than those of KA or SC carcasses, whereas kidney fat weight and percentage were greater (P < 0.001) in carcasses from KA and SC than DO and SU lambs. Lean maturity was similar (P = 0.32) among breed-types. However, skeletal maturity was greater (P < 0.001) in SU than hair-sheep carcasses. Flank-streaking scores were similar (P = 0.19) among the breed-types, but conformation scores were higher (P < 0.001) for DO and SU carcasses and resulted in higher (P < 0.001) quality grades than SC carcasses. The LM of SU lambs was lighter (higher L^* values; P < 0.05) than that of KA and SC lambs, whereas the LM from DO lambs was redder (higher a^* values; P < 0.001) than SC and SU and more (P < 0.001) yellow than that of the other breed-types. Chops from SU lambs were tougher (higher shear force values; P < 0.007) than chops from the hair-sheep breeds. Results of this study indicate that ADG, carcass muscularity and meat quality were similar between DO and SU lambs, and, although fatter, carcass muscularity of KA was similar to that of DO lambs.     

Effects of lambing season,sex and birth type on growth performance in Norduz lambs

The aim of this study was to evaluate effects of two production systems (spring and winter), sex and birth type on growth performance in Norduz lambs. Data were collected using 103 and 140 lambs born during the winter and spring, respectively. Lambs born in the winter were heavier (P < 0.01) than those born in the spring at birth, 90 and 180 days of age by 0.5, 1.6 and 1.7 kg, respectively. Ram lambs were heavier (P < 0.01) than ewe lambs at birth, 90 and 180 days of age by 0.5, 1.0 and 2.3 kg, respectively, while lambs born as singles were heavier (P < 0.01) than lambs born as twins at birth, 90 and 180 days of age by 0.9, 1.6 and 2.3 kg, respectively. Lambs born in the winter recorded a higher (P < 0.01) pre-weaning ADG (15 g/day) than spring-born lambs, while ram lambs recorded a higher (P < 0.01) pre-weaning ADG (11 g/day) than ewe lambs. The effect of birth type was not significant on pre-weaning ADG. The influence of lambing season and sex were also not significant on post-weaning ADG. Lambs born as singles recorded a higher (P < 0.01) post-weaning ADG (16 g/day) than lambs born as twins. Results suggest the winter season to give rise to heavier lambs at weaning and post-weaning and suggest lambs born in different seasons to have distinctly different growth patterns. The data also confirm that the influence of sex and type of birth on growth to be very important and to be take into account sheep production.     

Partial replacement of barley grain for corn grain: Associative effects on lambs’ growth performance

Our objective was to study the positive effects of partial replacement of barley grain for corn in high concentrate diets on growth performance of growing lambs, and to determine the minimum amount of corn needed to produce such effects. Thirty-three male Awassi lambs weaned at 60 days of age were divided into three groups of 11 according to their live weight and offered three isonitrogenous diets. The control diet (B) contained 81 and 14% barley grain and wheat straw, respectively (DM basis). Corn grain replaced barley grain at 10 and 20% of dietary DM for low (LC) and high (HC) corn diets, respectively. Barley had a higher (P < 0.05) rate of digestion (11.5%/h) compared with corn (8.3%/h). The in vitro 30-h digestion extent was also higher (P < 0.05) for barley. The digestion rate for the B diet was higher (P < 0.05) compared with the HC diet, whereas the value for the LC diet was intermediate. Lambs fed LC and HC diets consumed more (P > 0.05) DM (average = 855 g/day) compared with lambs fed B diet (757 g/day). DM and CP digestibilities were similar among diets and averaged 67.0 and 64.2%, respectively. Final BW, BW change and average daily gain (ADG) for lambs fed HC were higher (P < 0.05) compared with B and LC. Moreover, lambs that consumed LC tended (P = 0.12) to grow faster than lambs fed B. Feed to gain ratio was lower (P < 0.05) for lambs fed HC (4.6) compared with B and LC (5.2). In summary, positive associative effects of partial replacement of barley with corn in high concentrate diets for fattening sheep were detected. However, a minimum of 20% replacement of dietary DM from barley with corn was needed to positively improve both performance and feed efficiency.     

Effects of dietary aluminum source and concentration on mineral status of feeder lambs

A 100 d experiment was conducted to determine the effects of aluminum (Al) source and concentration on mineral status, emphasizing phosphorus (P), of 50 feeder lambs. Six treatments, fed at 10% of the total diet, were formulated using two sources of Al, AlCl₃ and an Al-based water treatment residual (WTR, 11.1% Al), with varying levels of Al and P: (1) control (10% sand, C), (2) low WTR (2.5% WTR and 7.5% sand, L-WTR), (3) AlCl₃ with added P (1% AlCl₃, 9% sand, and 0.4% P, AlCl₃ + P), (4) high WTR (10% WTR, H-WTR), (5) AlCl₃ (1% AlCl₃ and 9% sand, AlCl₃), and (6) high WTR with added P (10% WTR and 0.4% P, H-WTR + P). The total Al varied from 0.037 to 1.2% among diets. Only lambs fed the high WTR diet without P supplementation (H-WTR) decreased feed intakes. These lambs consumed about half as much feed as lambs on all the other treatments, and had lower (P < 0.05) BW from d 84 on. Lambs receiving the H-WTR had the lowest bone Ca, P and Mg concentrations (fresh basis, mg/cm³) and lowest bone mineral content (BMC) as determined by radiographs (mm of Al). Results for the lambs on H-WTR were confounded by the greatly reduced feed intake of animals on this treatment. Plasma P decreased in all lambs consuming Al, regardless of Al source, but the effects were less severe in animals provided additional P supplementation (AlCl₃ + P and H-WTR + P). Apparent absorption of P was affected by concentration and source of Al in two metabolism trials (n = 42) beginning on d 34 and d 70, respectively. In the first trial, d 34, lambs receiving AlCl₃ treatment had reduced apparent P absorption, −17.7% (P < 0.05), when compared to all other treatments. In the d 70 trial, lambs receiving both AlCl₃ and H-WTR treatments were negatively impacted (P < 0.05) compared to the control, −20.9 and −2.5% apparent P absorption, respectively, but were no longer different from one another (P > 0.05). Diets containing 1.2% Al as WTR without P supplementation depressed feed intakes, weight gains, plasma P concentrations (P < 0.05), and BMC. However, given adequate P supplementation, even lambs consuming this amount of Al did not suffer detrimental effects, as lambs on H-WTR + P did not differ from the control (P > 0.05) in feed intakes, weight gains, or BMC.     

Growth,carcass and cooked meat characteristics of lambs sired by Dorset rams heterozygous for the Callipyge gene and Suffolk and Texel rams

Dorset (D) rams heterozygous for the Callipyge gene were single—sire mated to non-carrier ewes to produce Callipyge heterozygous (CLPG, n = 49) and normal (D, n = 33) lambs. Suffolk (S) and Texel (T) rams were mated to similar ewes to produce non-carrier crossbred S (n = 55) and T (n = 52) lambs. Lambs were finished on a high-energy diet to a target live weight of 57 kg. Pre-slaughter weight was recorded for each lamb prior to its transfer and slaughter through a commercial facility. Hot carcass weight and kidney and pelvic fat (KPF) were recorded at slaughter. Chilled carcasses were measured then fabricated into trimmed retail cuts by plant personnel. Each cut was weighed, and two loin chops were collected from each carcass for later cooking. CLPG lambs had the highest dressing % (53.6 versus 49.8–50.6; P < 0.05). At the same cold carcass weight, CLPG lambs had larger longissimus muscle areas (19.5 cm² versus 14.0–15.2 cm² for the rest; P < 0.05), less KPF (0.9 kg versus 1.04–1.13 kg; P < 0.05), less carcass fat (P < 0.05 for all measures), shorter carcasses (60.7 cm versus 61.8–64.7 cm; P < 0.05), and heavier trimmed sirloins, legs, and shoulders than any other group (a11 P < 0.05). They were similar to S lambs in receiving the lowest mean USDA yield grade. CLPG carcasses had the highest proportion of carcass weight represented by trimmed cuts (70% versus 65.7–67.8% for the rest; P < 0.05), the highest proportion of trimmed cuts (62.2% versus 59.7–60.6% for the rest; P < 0.05) represented by the most valuable cuts (leg + loin + rack + sirloin), and the highest composite carcass value ($135.8 versus $125–129 for the rest; P < 0.05). CLPG lambs also produced loin chops with the highest mean Warner–Bratzler shear values (5.4 kg versus 2.8–2.9 kg for the rest; P < 0.05) and the highest % cooking loss (31% versus 29–29.6% for the rest; P < 0.05).     

Effect of group size on feed intake,aggressive behaviour and growth rate in goat kids and lambs

The effects of different group sizes on feed intake, growth and behaviour in penned kids and lambs were studied in an experiment (Exp. 1) with 30 kids and 30 lambs used in 3 periods. In each period, animals were divided into five group sizes. The group sizes were one, two, three, four or five animals per pen. In a second experiment (Exp. 2) 36 kids and 36 lambs were allotted to two groups of one and five animals per group. The diet consisted of Jackfruit (Artocarpus heterophyllus) and Acacia (Acacia mangium) foliages, sugar-cane (Saccharum officinarum) and concentrate. The foliages were given ad libitum, equal to 130% of intake of fresh matter of the group the previous day, and concentrate and sugar-cane were given at a level of 10 g dry matter (DM)/kg initial body weight. The time for each period in Exp. 1 was 21 days, with the last 7 days for data collection. The behaviour observations were done during the last 4 days of each data collection period. The time for Exp. 2 was 84 days.In Exp. 1, the kids had a higher total DM intake (DMI) (P = 0.011) and DMI of Jackfruit (P < 0.001) than the lambs. Total intake increased linearly as group size increased (P = 0.03). When feeding Jackfruit or sugar-cane aggressive behaviours recorded per pen or per animal increased linearly with group size. In Exp. 2, there was no difference in total DMI between kids and lambs, but kids had a significantly higher DMI of Jackfruit and a lower DMI of sugar-cane. Total DMI and DMI of Jackfruit and sugar-cane were similar for the group sizes of five animals and one animal, but kids showed a higher total intake and intake of Jackfruit in the group sizes of five animals, while a higher intake was obtained in single pens for lambs. The weight gain was higher (P < 0.05) for the lambs compared to the kids, but similar for the animals in the group size of one or five animals. The feed conversion ratio (FCR) was significantly lower for the lambs compared to the kids, but not different between group sizes. The water intake of the lambs was higher (P < 0.05) than that of the kids in both experiments and the animals in the pens with high density drank more water than the animals in individual pens only in Exp. 2. In conclusion, increasing the number of animals in the pens increased feed and water intake and also aggressive behaviours and did not improve growth rate or feed conversion ratio.     

Comparison of the behaviour of Awassi lambs in cafeteria feeding system with single diet feeding system

This study was carried out to compare behavioural activities of Awassi lambs in cafeteria feeding system with conventional feeding (control) that animals fed concentrate. Sixteen, 3-month-old male lambs were housed individually for 42 days. The main effect was on the feeding systems, cafeteria and control. Cafeteria lambs (n=8) were offered the main ingredients (barley, cotton seed meal (CSM), wheat bran and alfalfa straw), while control animals (n=8) were fed a single diet (48% barley, 22% cottonseed meal, 18% wheat bran, 10% alfalfa and 2% vitamin–mineral mixture; having 2467 Kcal ME and 161 g kg⁻¹) with the same main ingredients with slightly higher nutrient content for growth. Food and water intakes were recorded daily, while behavioural observations were recorded twice a week for a period of 1 h at 5 min intervals at 13:00, 16:00, 19:00, 22:00, 01:00, 04:00, 07:00 and 10:00 h after the initiation of daily feeding. After every 5 min, each lamb was monitored to determine its eating, ruminating, drinking, walking, standing, playing, resting and other activities.Cafeteria lambs selected a diet that matched their growth requirement as did control lambs. However, cafeteria lambs ate more (P<0.01). Cafeteria animals preferred cotton seed meal (42.4%) to barley (32.9%) without changing their water intake, final live weight and daily gain (P>0.05). Cafeteria lambs also had higher rates of eating (22% versus 19%, P<0.01), ruminating (24% versus 23%, P>0.05) and resting (29% versus 23%, P<0.01) than the control lambs. On the other hand, cafeteria lambs spent less time standing (19% versus 25%, P<0.01) and walking (1.5% versus 2.1%, P<0.01) compared with control animals. In conclusion, cafeteria lambs selected a diet that matched their presumed biological (behavioral and nutritional) needs without changing their growth performance.     

Influence of maternal undernutrition on the behaviour of juvenile lambs

The objective of the present experiment was to determine the implications of prenatal undernutrition on the behaviour of juvenile lambs. Dams of one group (C) were fed 100% of the recommended requirements throughout pregnancy, while those of two other groups were fed 50% of the control nutrient allowance during the first 30 days of pregnancy (R1) or 50% of the control nutrient allowance from days 31–100 of pregnancy (R2). Between 2 and 5 months old, behaviour of lambs was tested by the implementation of 2 types of test: isolation and novelty. There were no statistical differences between lamb treatments in escape behaviour and heart rates during isolation test, or the latency to approach a novel or a familiar object in the novelty test in tests conducted at 2, 3, 4 and 5 months of age.Male lambs showed a tendency of turning to the right-hand side of the test pen, irrespective of treatment group, between the age of 2 and 5 months old. A greater proportion of C compared to R1 males turned right at the age of 2 and 5 months old (P < 0.05). Significant differences concerning laterality were found also between C and R1 female lambs at the age of 2 and 4 months old (P < 0.001), between C and R2 male lambs at the age of 2 months old (P < 0.05), between C and R2 female lambs at the age of 4 and 5 months old (P < 0.01), between R1 and R2 male lambs at the age of 2 and 5 months old (P < 0.05) and between R1 and R2 female lambs at the age of 2 months old (P < 0.001).It is concluded that prenatal undernutrition during different periods of pregnancy had no effect on fear-related behaviour, but effect on laterality at the early stages of lamb age between 2 and 5 months old.     

Effect of different levels of concentrate allowances on rumen fluid pH,nutrient digestion,nitrogen retention and growth performance of weaner lambs

This experiment was conducted for 90 d to assess the effect of feeding graded levels of concentrate allowance on rumen fermentation characteristics, performance and nutrient utilisation of weaner lambs on restricted or high concentrate allowance using 60 weaner lambs of initial average live weight of 13.90 kg BW in a randomized design. The experimental treatments were 15 or 25 g kg⁻¹ BW or ad libitum concentrate allowance. Roughage source which contained Khejri (Prosopis cineratia) and Siris (Albizia lebback) leaves in 50:50 ratio was offered ad libitum to all the animals. Lambs supplemented with 15 g or ad libitum concentrate had similar dry matter intake (4.2 kg/100 kg BW) but significantly (p < 0.01) lower than 25 g concentrate supplemented group (4.9 kg/100 kg BW). Organic matter and CP intakes increased with increasing concentrate supplementation. Apparent digestibilities of dry matter, organic matter, CP, NDF, ADF and cellulose were significantly (p < 0.01) higher in ad libitum concentrate supplemented than 15 and 25 g concentrate supplemented lambs. Daily ME intake was significantly (p < 0.05) higher in 25 g and ad libitum concentrate supplemented lambs while ME intake kg⁻¹ gain was lower in ad libitum concentrate supplemented lambs (57 MJ kg⁻¹ gain) than those supplemented with 15 or 25 g concentrate (91 MJ kg⁻¹ gain). Generally, average daily gain increased with increasing levels of concentrate supplementation. Ad libitum concentrate supplemented lambs had significantly (p < 0.01) higher daily gains (151 g) than 15 and 25 g concentrate supplemented lambs (77 and 98 g, respectively). Feed efficiency was similar for 15 and 25 g concentrate supplemented lambs but significantly (p < 0.01) lower than the ad libitum concentrate supplemented lambs. All animals were in positive N-balance and the N-balance increased with increasing concentrate supplementation. Mean rumen fluid pH was significantly (6.6, p < 0.01) lower in ad libitum concentrate supplemented lambs compared to 15 or 25 g concentrate fed lambs (6.9). Rumen NH₃-N and total-N-concentrations peaked at 3 h post-feeding. Optimum rumen fluid pH, better nutrient digestibilities, higher N-retention improved growth by 49% of ad libitum concentrate fed lambs.     

Effects of dietary forage-to-concentrate ratios on performance and carcass characteristics of growing fat-tailed lambs

This study was conducted to evaluate the effects of using different dietary forage-to-concentrate ratios on growth performance and carcass characteristics of eighty Chall male fat-tailed lambs, averaging 165 ± 15 (SD) days of age and body weight of 38.4 ± 4.8 (SD) kg, randomly assigned to four diets containing alfalfa hay-to-concentrate ratios (DM basis) of 70:30 (C30), 50:50 (C50), 30:70 (C70), 10:90 (C90). Metabolizable energy (ME) contents were, 9.12. 9.96, 10.67, and 11.34 MJ/kg dry matter (DM) and crude protein (CP) contents were 143, 152, 161, and 174 g/kg for the C30, C50, C70, and C90 diets, respectively. Sixteen lambs (4 lambs/treatment) were slaughtered at the end of feeding period (84 days). Dry matter intake and feed conversion ratio (FCR) (i.e., kg DM/kg gain) decreased linearly (P<0.001) as concentrate level increased in the diet. However, a linear increase (P<0.001) for ME intake and a quadratic increase for average daily gain (ADG, P<0.001) and final body weight (P<0.01) were observed with increasing dietary concentrate. Slaughter weight, eye muscle area, and weights of lean, bone, neck, shoulder, rack–loin, leg, skin, head, lung, and spleen were not affected by the experimental diets. However, as dietary concentrate increased, a linear increase for dressing percentage, feet weight (P<0.001), and backfat thickness (P<0.02), a quadratic increase for empty body weight (EBW, P<0.02), weights of hot and cold carcass (P<0.001), subcutaneous fat (P<0.02), total fat (P<0.01), brisket–flank (P<0.04), and tail fat (P<0.001), a linear decrease for weights of liver (P<0.01), and heart (P<0.05), and a quadratic decrease for lean-to-fat ratio (P<0.02) were observed. This study indicates that in Chall fat-tailed lambs the increase of dietary concentrate (up to 700 g/kg) improves growth rate, FCR and dressing percentage with negative effect on carcass lean-to-fat ratio.     

Effect of strategic helminthosis control on mortality of communally grazed Menz lambs of smallholders in the cool central Ethiopian highlands

A 3-year longitudinal study was conducted to evaluate the effects of strategic anthelmintic dosing on communally grazed village sheep in Gera Keya district in the central highlands of Ethiopia. Ewes were stratified by weight and randomly allocated to three treatment groups: untreated control (TG1), twice-dosed per year (TG2; for both nematodes and trematodes in mid-January and mid-June) and four-time-dosed per year (TG3; in June for nematodes, in August–September for nematodes and adult Fasciola, in November–December and January–February for immature liver flukes). The fixed effect of treatment, lamb sex, dam parity, season and year of birth on mortality from birth to 90, 180, 270 and 365 days was analyzed. Least square means of lamb mortality from birth to 90, 180, 270 and 365 days were 11.3, 16.8, 18.0 and 19.5%, respectively. Anthelmintic treatment had significant effect (P < 0.05) on mortality of lambs at all ages: lambs in TG3 had consistently higher mortality than lambs in TG2. The lambs in TG3 were worse in terms of survival from birth to 180 days even when compared with the control group (TG1). Mortality rate in male lambs was twice as high compared to their female contemporaries at all ages (P < 0.001). Season of birth had significant (P < 0.01) effect on lamb mortality at all ages. Lambs born during rainy season had the lowest mortality in the first 6 months (0–90 and 0–180 days) of age than those born during short rainy or dry seasons. Instead of frequent mass drenching, discriminatory drenching on a case-by-case basis should be considered to improve lamb survival.     

Sexual performance of Awassi ram lambs reared in different sex composition groups

The objective of this study was to evaluate the effect of sex composition of the group of lambs before puberty on later sexual performance in Awassi ram lambs. Thirteen Awassi ram lambs of the same age were raised in either all-male group (n = 7) or in a group mixed with females (n = 6) from weaning to puberty. Blood samples, body weights (BW) and scrotal circumferences (SC) of ram lambs were recorded between eight and 10 months of age. Sexual performance testing was performed at 9 months of age by individually exposing ram lambs to oestrous females on five occasions. Body weight and SC were greater (P < 0.01) in the all-male compared with the mixed group. Plasma testosterone concentrations were not influenced (P > 0.05) by treatment. Plasma testosterone concentrations were significantly correlated (P ≤ 0.05) with BW (r = 0.3) and SC (r = 0.4). No treatment effects were detected regarding bouts of leg-kicking. Bouts of anogenital sniffing, the frequency of mount attempts and mounting frequency were greater (P < 0.05) in the all-male group. Even though the frequency of raising the fat tail of females was similar between the two treatments, the mixed group tended to be (P = 0.08) more efficient in doing so than the all-male group (higher tail raising/mount). Results of the current study indicate that mixing groups of ram and ewe lambs before puberty may be insufficient to improve later sexual performance of ram lambs.     

Reproductive responses of ram lambs under short-term exposure to endophyte-infected tall fescue seed

Our objective was to determine the influence of short-term exposure to endophyte-infected tall fescue on reproductive function of ram lambs. Rams (214 days of age) were fed a diet free of endophyte-infected fescue seed (EF; n = 8) or endophyte-infected fescue seed (EI; n = 9; 34% of diet; 4.8 μg g⁻¹ ergovaline) for 6 weeks. Feed offered to EF rams, individually fed, was reduced to the average intake of EI lambs from previous day so that intake was similar between treatments and averaged 2.4% BW (DM basis), leading to daily intake of 33.7 μg ergovaline kg⁻¹ BW for the EI fed lambs. Daily high ambient temperature for the trial ranged between 16 and 26 °C. Respiration rate and rectal temperature were measured at 14:00 daily. Blood was collected for serum concentrations of prolactin (weekly) and testosterone (twice weekly). Body weight and body condition scores (BCS; 1 = thin; 5 = fat) were determined every 14 days. Scrotal circumference, scrotal skin temperature, and semen characteristics were determined weekly. Rams were slaughtered after 6 weeks of feeding. Signs of fescue toxicosis in EI fed rams included increased rectal temperature (P < 0.001, R² = 0.11) and respiration rate (day, P < 0.001, R² = 0.25) when high ambient temperature exceeded 22 °C and reduced serum concentrations of prolactin (diet × day, P < 0.001). Body weight of EI fed rams tended to decrease after 36 days of feeding compared with EF fed rams (−3.0 kg versus 0.51 kg; P < 0.07) and BCS was similar between treatment throughout the trial. Serum concentrations of testosterone were greater in EI compared with EF fed rams (diet × day, P < 0.005, R² = 0.08). Scrotal skin temperature, scrotal circumference, semen volume, percent sperm motility, and percent abnormal sperm were similar between treatments. Spermatozoa concentration tended to be greater in EF compared with EI fed rams after 43 days of feeding (P < 0.10; R² = 0.15). Rate of forward movement of spermatozoa tended to increase at a greater rate between Days 8 and 29 in EF compared with EI fed rams (diet × day, P < 0.08). Feeding endophyte-infected fescue seed to ram lambs was associated with potential decreased fertility and increased serum concentrations of testosterone. Short term exposure of endophyte toxins to male ruminants may negatively impact reproductive responses. Feeding for longer periods may further reduce fertility and merits further research.     

Effect of dietary cobalt supplementation on plasma and rumen metabolites in Mehraban lambs

Two experiments were conducted to study the effects of different levels of dietary cobalt on performance, plasma and rumen metabolites and nutrient digestibility in Mehraban male lambs. Experiment 1: 28, 8–9-month-old lambs were randomly divided into four groups. Animals were fed a basal diet containing 0.088 mg Co/kg DM and were supplied with 0 (control), 0.25, 0.50, or 1.00 mg Co/kg DM as reagent grade CoSO₄·7H₂O. The experiment lasted for 70 days. Experiment 2: four lambs from each group in Experiment 1 were randomly allocated to the individual metabolic crates to measure the effects of dietary Co on nutrient digestibility. Final body weight, average daily gain and gain efficiency were higher (p < 0.05) in the group supplemented with 0.50 mg Co/kg DM compared to other groups. Plasma glucose and vitamin B₁₂ concentrations increased (p < 0.05) at all levels of Co supplementation on day 68 of the experiment and for vitamin B₁₂ were higher (p < 0.05) at 0.50 and 1.00 mg Co/kg DM compared to 0.25 mg Co/kg DM. There was no significant difference among treatments for TVFA and ruminal fluid pH. Digestibility of dry matter, organic matter, crude protein and neutral detergent fiber increased (p < 0.05) by Co supplementation, but did not differ among Co supplied treatments. The obtained results showed that lambs fed the control diet containing 0.088 mg Co/kg DM had a reduced appetite and gained less than the supplemented animals, suggesting that the level of 0.088 mg Co/kg DM was inadequate for normal growth of Mehraban male lambs, and a total level of 0.58 mg Co/kg DM might be optimum level for enhancing performance.