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.     

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.     

Effect of follicular wave synchronization on in vitro embryo production in heifers

Aiming to achieve the ideal time of ovum pick-up (OPU) for in vitro embryo production (IVP) in crossbred heifers, two Latin square design studies investigated the effect of ovarian follicular wave synchronization with estradiol benzoate (EB) and progestins. For each experiment, crossbred heifers stage of estrous cycle was synchronized either with a norgestomet ear implant (Experiment 1) or a progesterone intravaginal device (Experiment 2) for 7 d, followed by the administration of 150 μg d-cloprostenol. On Day 7, all follicles >3 mm in diameter were aspirated and implants/devices were replaced by new ones. Afterwards, implant/device replacement was conducted every 14 d. Each experiment had three treatment groups. In Experiment 1 (n = 12), heifers in Group 2X had their follicles aspirated twice a week and those in Groups 1X and 1X-EB were submitted to OPU once a week for a period of 28 d. Heifers from Group 1X-EB also received 2 mg EB i.m. immediately after each OPU session. In Experiment 2 (n = 11), animals from Group 0EB did not receive EB while heifers in Groups 2EB and 5EB received 2 and 5 mg of EB respectively, immediately after OPU. The OPU sessions were performed once weekly for 28 d. Therefore, in both experiments, four OPU sessions were performed in heifers aspirated once a week and in Experiment 1, eight OPU sessions were done in heifers aspirated twice a week. Additionally, during the 7-d period following follicular aspiration, ovarian ultrasonography examinations were conducted to measure diameter of the largest follicle and blood samples were collected for FSH quantification by RIA. In Experiment 1, all viable oocytes recovered were in vitro matured and fertilized. Results indicated that while progestin and EB altered follicular wave patterns, this treatment did not prevent establishment of follicular dominance on the ovaries of heifers during OPU at 7-d intervals. Furthermore, the proposed stage of follicular wave synchronization strategies did not improve the number and quality of the recovered oocytes, or the number of in vitro produced embryos.     

Socio-spatial criteria are important for the establishment of maternal preference in lambs

At lambing, ewes (Ovis aries) tend to isolate themselves from the flock and this is believed to be beneficial to the early relationship with their young. Later, they return to the flock and lambs progressively interact with other conspecifics. This study focused on the importance of isolation and socio-spatial factors on maternal recognition in lambs. All the ewes gave birth in individual 2 m² pens and lambs were able to interact freely with their mothers. A first experiment investigated the role of isolation: INT1 lambs could progressively interact with other mothers and young in a pen which was increased in surface area from birth to 24 h (0–6 h: 1 ewe, 1 litter, 2 m²; 6–12 h: 2 ewes, 2 litters, 4 m²; 12–24 h: 4 ewes, 4 litters, 8 m²); ISO lambs remained in small pens (2 m²) and only with their mothers for 24 h. The lambs were submitted to a 5 min choice test between their own mothers and an alien ewe. At 12 h INT1 lambs, unlike ISO lambs, showed a clear preference for their mothers. ISO lambs still did not show any maternal preference at 24 h. The second experiment investigated the relative importance of social interactions while keeping the same space allowance for the two groups: INT2 lambs as described for INT1 in Experiment 1, and SPA lambs that remained isolated from the flock with their mothers but had the same increase in pen surface area as INT2 lambs. Both INT2 and SPA lambs displayed a preference for their own mothers at 12 h but INT2 lambs did so more rapidly. Our data also suggest that INT1 and INT2 lambs chose their own mothers at a distance. These results demonstrate that progressively increasing social interactions with flock members other than the mother facilitates the establishment of a preference for the mother in lambs. Increasing space allowance only also seems to have facilitating effects. This suggests that a rich socio-spatial environment from birth has beneficial effects on the development of filial bonding.     

Effects of nutritional level during late pregnancy on colostral production and blood immunoglobulin levels of Karakul ewes and their lambs

An experiment was conducted to examine the changes in colostral production and composition in Karakul ewes fed at different nutritional levels. Pregnant ewes were randomly allotted to one of four groups (n = 20 per group) 90 days after artificial insemination. Three groups were fed with total mixed rations supplying 90, 100 and 110% of the NRC requirements, respectively, and the last group served as the control feeding on natural vegetations until parturition. Blood samples were taken from the jugular vein during late pregnancy, and soon after lambing. Fifteen singleton ewes from each group were hand-milked completely at 1, 12 and 24 h post-lambing. Samples of colostrum were obtained and the lambs were fed with their ewe's colostrum (30 g/kg BW) at each milking. Blood samples were taken from the lambs before receiving their first colostrum, and again at 24 and 48 h post-lambing. Ewes on 110% NRC diet produced significantly (P < 0.01) more colostrum than did the ewes in other groups. Feeding level did not have a significant effect on the IgG level of the colostrums and blood sera of ewes and lambs. Mean IgG concentration in the ewe serum was greatest during late gestation (1–2 months before lambing) and were significantly reduced at 1 h post-lambing. Non-immunoglobulin composition of colostrum was not significantly affected by the treatment. There was a significant correlation between IgG levels of the ewe serum and colostrum (r = 0.64, P < 0.0001). Mean weight of the ewes on the control ration at lambing and the mean birth weight of their lambs were significantly lower as compared with other dietary groups. The results suggested that hand-feeding of Karakul ewes on poor rangeland vegetation with 110% NRC for 2 months before parturition increased colostral production, decreased the ewe loss and increased lamb birth weight which is beneficial to lamb survival.     

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.     

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.     

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.     

Comparison of four techniques to estimate milk production in singleton-rearing non-dairy ewes

Accurate estimates of milk production or milk intake are difficult, as all methods interfere to some degree with the natural behaviour of the dam and her young, and potentially alter milk yield itself. The present study compared milk yield obtained by the “oxytocin” method, udder dimensions (UD), the isotope dilution method, and live weight change of the lamb, in an attempt to select the most accurate and convenient way of measuring milk production in non-dairy sheep. In addition, the study investigated which of the three milk-estimation techniques was an accurate predictor of growth rates of lambs. Thirty-seven singleton-bearing and rearing ewes were milked once a week, for seven consecutive weeks, using the “oxytocin” method. Prior to each afternoon milking, the external dimensions of the ewe's udder were measured. Lambs were weighed weekly for the first seven weeks of life and live weight change was calculated. The deuterium oxide (D₂O) dilution technique was used to estimate milk intake of the lambs and performed at approximately 7 days post-partum and finishing on approximately day 14. Pearson's correlation coefficients and multiple regression coefficients among techniques were calculated. The UD-models at d7 (R² = 0.35), d35 (R² = 0.36) and d42 (R² = 0.34), were the best models explaining variation in milk yield (concordance correlation coefficient (CCC) = 0.49; 0.53; 0.51; for d7, d35 and d42, respectively). The lamb live weight-change model explained the variation in milk yield best at d28 (R² = 0.32; CCC = 0.49), at d35 (R² = 0.22; CCC = 0.36) and at d42 (R² = 0.28; CCC = 0.44). At d14, the intake of milk by lambs as measured by the D₂O technique, did not explain the variation in milk yield. In conclusion, udder dimensions, lamb live weight change and lamb milk intake are relatively poor estimators of the milk yield of singleton-rearing ewes obtained by the “oxytocin” method. Additionally, udder dimensions, milk yield and lamb milk intake do not give an accurate prediction of growth rates of singleton lambs. These results emphasize that there is a difference between ewe milk production potential and lamb milk intake, which need to be considered when estimating milk production in non-dairy animals.     

Initiation of the breeding season in ewe lambs and goat kids with melatonin implants

Sixty-eight female and 4 male lambs of the Chios breed born in autumn (September–October) and 48 female and 4 male kids of the Damascus breed also born in autumn (November), were used to evaluate the effect of melatonin implants (Regulin^®) on the initiation of the breeding season. For each species and sex, half of the animals were either left untreated to serve as controls (C) or received ear implants (females one and males two implants) of melatonin (MEL) in May (spring). Each C and MEL group of females was kept separately and away from males for 5 weeks after implantation and then, C and MEL males were joined with the respective groups for 45 (sheep) and 35 days (goats). Animals not conceiving during the early June–July breeding season, were mated again in September (natural breeding season). The reproductive performance and the 60-day milk yield of animals giving birth during the two seasons were compared. Early in the season (mid November–December), significantly more MEL than C ewes and goats gave birth (75.5% versus 23.5%, p < 0.01; 70.8% versus 37.5%, p < 0.05, respectively). For both species, most of the other characteristics examined were significantly affected by season, but not by treatment. Females giving birth early in the season were approximately 80 days younger at parturition and recorded a lower body weight at mating than those giving birth in the natural February–March season. In the first mating period, the animals mated and conceived had similar body weights to those not mated. The natural, compared with the early June–July mating season, was associated in sheep with higher litter weight at birth (7.0 kg versus 5.8 kg, p < 0.05) and in sheep and goats with a higher number (p < 0.05) of offspring born live (1.78 versus 1.38; 2.0 versus 1.61, respectively) and weaned (1.74 versus 1.36; 1.82 versus 1.35, respectively). Total litter size at birth and 60-day milk yield after weaning, were not significantly different between the two seasons. It could be concluded that melatonin implants administered during the last month of spring in autumn-born female Chios sheep and Damascus goats, advanced the initiation of their breeding season by about 80 days when joined with young males also treated with melatonin implants. The overall reproductive performance and milk yield of animals breeding early, was satisfactory and comparable to that of animals breeding in the natural breeding season.     

Use of lincomycin to control respiratory infections in lambs: Effects on health and production

The efficacy of lincomycin to control respiratory infections in lambs was assessed in two trials. In trial I, 72 lambs with active mycoplasmal pneumonia were allocated as follows: lambs in group T2 were treated with lincomycin (5 mg kg⁻¹ bodyweight, intramuscularly) twice 2 days apart, those in group T3 with lincomycin (5 mg kg⁻¹ bodyweight, intramuscularly) thrice with 2-day intervals, those in group O with oxytetracycline (20 mg kg⁻¹ bodyweight, intramuscularly) twice 4 days apart and those in group C were controls. In trial II, 48 25–30-day-old clinically healthy lambs were allocated as follows: lambs in group P2 received two injections of lincomycin (5 mg kg⁻¹ bodyweight, intramuscularly) when 30- and 60-day-old, lambs in group P1/30 received one injection of lincomycin (5 mg kg⁻¹ bodyweight, intramuscularly) when 30-day-old, lambs in group P1/60 received one injection of lincomycin (5 mg kg⁻¹ bodyweight, intramuscularly) when 60-day-old and lambs in group C were controls. In trial I, treatment with lincomycin was associated with improved clinical scores; clinical cure rate 42 days after treatment was 87%, 100%, 87% and 0% for group T2, T3, O and C, respectively (P < 0.001); treated lambs produced 18.5% (T2) or 26.5% (T3) heavier carcass than controls; no lung lesions were seen in group T3 lambs, whilst they were evident in 22% of group T2 or group O lambs and in 72% of control lambs; microorganisms were isolated from lung tissue samples of 5 group C and 1 group O lambs. In trial II, administration of lincomycin was associated with smaller clinical scores; prevalence rate of respiratory disorders at the end of the trial was 17%, 42%, 42% and 58% for group P2, P1/30, P1/60 and C, respectively (P < 0.01); treated lambs were >4.5% heavier than controls; lung lesions were recorded in 1 group P2, 2 group P1/30 and group P1/60 and 5 group C lambs; microorganisms were isolated from 1 group P2, 3 group P1/30, 2 group P1/60 and 5 group C lambs. It is concluded that administration of lincomycin is effective for the treatment and the prevention of mycoplasmal atypical pneumonia in lambs.     

Oocyte pick-up in juvenile lambs affects neither onset of puberty nor their future fertility

A study was designed to evaluate whether the time of onset of puberty and fertility of young ewe lambs would be affected by oocyte pick-up conducted in single or repeated sessions during the first months of lambs' live. Five groups of lambs from the Karagouniko breed were used (A-E each n=12). In group A no treatments were applied (control group) while, laparoscopical follicular aspiration (OPU) was performed early in the third, fourth and fifth month of lambs age (groups C-E, respectively). From the second to fifth month of their age, group B lambs were aspirated four times in monthly intervals. All lambs were weighed at birth, weaning, at second month and monthly thereafter until the eighth month of age. Progesterone priming and ovarian stimulation by serial FSH administrations proceeded each OPU session. To determine onset of puberty blood progesterone concentration was assayed in samples collected initially every week and after the seventh month of age twice weekly. From the seventh month a fertile ram was introduced in each group and oestrous behavior/mating was daily monitored and recorded. Pregnancy diagnosis was carried out by transabdominal ultrasound scanning 55 days after rams' removal. At the fourth and fifth month of age group B lambs were lighter (p<0.05) than controls, but this difference was later equalized. The time of onset of puberty did not differ between groups (p=0.069) and ranged between 224 and 270 days. Some animals (n=15) entered puberty with a full-length luteal phase having progesterone concentration greater than 1ng/ml, while others (n=32) exhibited one or two short luteal phases before luteal length restoration. During the first breeding season 41 animals were fertilized and maintained pregnancy to term, without noticeable differences between groups (p=0.555). During the second breeding season, all ewes were naturally served and lambed at the expected time. It is concluded that OPU in young dairy lambs does not affect the time of onset of puberty, the endocrine profile of the lambs and it does not compromise their future fertility even if it is applied at four successive months.     

Effects of different forms of olive cake on the performance and carcass quality of Awassi lambs

Effects of form of olive cake (OC) on growth performances and carcass quality were studied on forty-eight Awassi lambs. All lambs were male with an average body weight of 29.5 kg (S.D. = 2.3 kg) at the beginning of the experiment. Animals were randomly divided into four groups of 12 lambs each. Lambs in each group received individually corn–soybean meal (SBM) total mixed rations (TMRs). Rations were incorporated with a fixed amount (149 g/kg DM) of OC of different forms: crude OC, a product of the three centrifugation extraction procedure (control group), alkali treated, ensiled and pelleted. All rations were isonitrogenous and isocaloric. The growth experiment lasted 10 weeks. In the following week, all lambs were slaughtered. At termination of the experiment, lambs fed crude, alkali treated or ensiled OC rations consumed more feed and gained more weight (P<0.05) than those fed the pelleted OC. This same trend was found for the feed conversion (FC), carcass and empty body weights (EBWs). However, external (hide, head and feet, HHF) and thoracic organs (heart and lungs, HL), gut and liver weights proportional to EBW (g/kg) were not affected by the form of OC. The form of OC had no effects on muscle (P=0.4) and bone (P=0.21) tissues. Carcass, pelvic, kidney fats and total carcass fats weights when expressed as g/kg EBW and the percent of carcass fat of total body fat (TBF) were lower in lambs fed the pelleted OC compared to those offered the other forms of OC. However, the subcutaneous, inter muscular and TBF fats weights (g/kg) were comparable among lambs in different OC form rations. Results from this work suggest that the treated OC had no advantages compared to crude in regard to parameters investigated in this research.     

Reproductive performance and milk yield in Awassi ewes following crossbreeding

The objective of this study was to evaluate the effect of crossbreeding Awassi ewes with either Charollais or Romanov sires, on pre-weaning lamb production as reflected by reproductive performance and milk production in the ewes. Two hundred and five, 3- to 6-year-old multiparous ewes of three breeds were allocated to three groups [Awassi (A; n = 56), F₁ Romanov × Awassi (RA; n = 78) and F₁ Charollais × Awassi (CA; n = 71)]. Upon lambing, ewes and their offspring were placed in a large pen in which they remained until the end of the trial. Body weight (BW) and body condition score (BCS) of the ewes and the BW of the lambs were recorded weekly from birth to weaning at 70 days of age. Milk production was recorded weekly from parturition to weaning. Pregnancy rates were not influenced by breed-type. Multiple births and the fecundity of ewes were greater (P < 0.05) in the RA group, compared to the A and CA groups—while the weaning percentage was similar between the breeds. Lamb birth and weaning weights were similar, while the kg lamb born per kg ewe lambed was greater (P < 0.05) in the RA group, compared to the CA group. The CA ewes recorded a higher BW (P < 0.01) and BCS (P < 0.01) than the other breed groups. Awassi ewes produced more milk (P < 0.01) throughout the observation period. Milk ash percentage was higher (P < 0.05) in the CA group, while the percentage of crude protein and dry matter was similar for the different groups. Results of the present study indicate that crossbreeding of Awassi ewes with Charollais and Romanov breeds decreased milk production in the progeny, without affecting lamb growth. The crossbreeding of Awassi with Charollais resulted in improved BW and BCS, while the crossbreeding of Awassi ewes with Romanov resulted in improved reproductive performance of the crossbreds. Crossbreeding Awassi ewes with exotic rams can thus be conducted to increase the number of lambs produced per ewe.     

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.     

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.     

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.     

Protein requirements of Texel crossbred lambs

A comparative slaughter trial was conducted to determine the protein requirements for maintenance and growth of feedlot Texel crossbred lambs. Thirty 11/16 Texel × 5/16 Ile de France crossbred noncastrated male lambs weaned at 42 days of age (16.2 ± 2.1 kg of shrunk body weight; SBW) were used. Five lambs were chosen randomly and slaughtered after 10 days of experimental management and diet adaptation (baseline group). Fifteen lambs were fed ad libitum and slaughtered at 25, 30 or 35 kg of SBW. The remaining 10 lambs were then assigned randomly to two levels of dry matter intake, either 70 or 55% of the ad libitum intake, and were slaughtered concomitantly with lambs slaughtered at 35 kg of SBW but given free choice access to feed. Total body N content and retention were determined. Additionally, six Texel × Ile de France crossbred lambs (30.4 ± 2.6 kg of SBW) housed in individual metabolic cages were used in a replicated 3 × 3 Latin square digestibility trial to evaluate diet digestibility and microbial protein synthesis at the different levels of feed intake. The endogenous N loss was 243 ± 29 mg/kg^0.75 of SBW, corresponding to a net protein requirement for maintenance of 1.52 ± 0.18 g/kg^0.75 of SBW. The metabolizable protein (MP) requirement for maintenance was 2.31 g/kg^0.75 of SBW, and the efficiency of MP use for maintenance was 0.66. Fleece-free body protein content decreased from 163 to 155 g/kg of empty body weight (EBW) as EBW increased from 13 to 28 kg. However, when protein in fleece was considered the whole-body protein content remained nearly constant. Net protein requirements for body weight gain and wool growth of lambs at 15 and 35 kg of SBW, and an average daily gain of 250 g, were 28.7 and 27.3 g/day and 3.8 and 5.8 g/day, respectively. Estimated efficiencies of MP use for body weight gain (k_pg) and wool growth (k_pw) were, respectively, 0.71 and 0.46. Growth pattern of the wool has a high influence on protein requirements of lambs. Texel crossbred growing lambs used in our study showed protein requirements for growth lower than those reported by the most nutritional systems.     

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.     

Net and metabolizable protein requirements for body weight gain in hair and wool lambs

Protein is one of the limiting factors in animal production, and the knowledge of protein requirements by livestock is crucial for the success of a commercial animal raising enterprise. Thirty-four castrated lambs, 17 of them F1 Ideal × Ile de France wool lambs and the remaining ones were Santa Inês hair lambs, with homogeneous initial BW, were used in the experiment. Five animals from each genotype were slaughtered in the beginning of the experimental period and used as reference. Diets (D) were composed of concentrate mix (C) and Cynodon sp. c.v. Tifton 85 hay (R), combined in three different ratios: D1 = 60C:40R; D2 = 40C:60R and D3 = 20C:80R. Animals of each group of three lambs, that showed simultaneously an initial BW of 20 ± 0.14 kg at the beginning of the dietary regimen, were slaughtered when one of them reached 35 kg, what always happened to be the one fed with D1. Net requirements for BW gain in wool lamb, fleece-free, ranged from 101 to 110 g of protein/kg BW, and for hair lamb ranged from 110 to 118 g of protein/kg BW. Net protein requirements for wool production ranged from 634 to 642 g/kg of produced wool. Hair lambs presented a 7.8–9.5% higher estimated net protein requirements than wool lambs, according to BW and daily weight gain (DG). Total net protein requirements for Santa Inês and wool lambs, with 30 kg of initial BW and an approximate 200 g mean DG, were 48.5 and 45.4 g/day, respectively. Metabolizable protein requirements for Santa Inês and wool lambs, with 20 kg of initial BW and an approximate 200 g mean DG were 59.4 g and 76.5 g/day, respectively. Net protein requirements for wool production was 64 g/100 g of produced wool. Thus, under the conditions of this experiment, it is concluded that hair lambs showed a higher concentration of protein in the body, more efficient use of the ingested protein and a consequent additional BW gain when fed isoproteic diets as compared to F1 Ideal × Ile de France wool lambs.