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.     

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 sodium bicarbonate and yeast on nutrient intake,digestibility, and ruminal fermentation of light-weight lambs fed finishing diets

This study was conducted to determine the effects of adding yeast culture and sodium bicarbonate to the finishing diets for lambs on intake, digestibility, rumina1 parameters and nitrogen retention. Twenty Pelibuey male lambs, weighing an average of 23 kg, were assigned to one of four treatment groups according to a completely randomized design with a 2 × 2 factorial arrangement. Treatments were: (1) no additive (NA); (2) 0.12% yeast culture (YC); (3) 0.5% sodium bicarbonate (SB); and (4) 0.12% YC and 0.5% SB. During the 7-day collection period, SB increased DM intake (P < 0.05), while YC had no effect (P > 0.05) on intake. Intake of non-fibrous carbohydrates (NFC) was increased (P < 0.05) with SB in the ration, but not by supplementing YC (P > 0.05). The YC had no effect (P > 0.05) on dry matter (DM), neutral detergent fiber (NDF) or non-fibrous carbohydrates digestibility. A higher intake of NFC with the SB treatments was associated with a lower (P < 0.05) digestibility. SB increased excretion of NDF (P < 0.05), which reduced its digestibility (P < 0.05) by more than 9 percentage units. Lambs consuming diets with SB had 27% more N retained, in contrast with those fed the basal diet without additives. Rumen pH was greater than the minimum considered to cause acidosis (≤pH 5.5). The SB reduced (P < 0.05) percent molar acetate and increased (P < 0.05) percent molar propionate, which is in contrast to what has been normally observed with dairy cattle research. A lower acetate to propionate ratio with the SB rations may be a result of a lower digestibility and a higher intake of NDF, which may have increased the rate of passage of fiber particles through the gastrointestinal tract.     

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.     

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.     

Physical and chemical characterization of lamb meat from different genotypes submitted to diet with different fibre contents

The objective of the study was to evaluate the effect of genotype and the dietary fibre concentration in the chemical composition and physical properties of lamb meat. Samples from 54 animals from Morada Nova and Santa Inês native breeds and Dorpper × Santa Inês half-breed were analyzed, which received two diets, one with 41.7% and another with 33.6% fibre content, until reaching the average slaughter weight of 30 kg. The design used was fully randomized 3 × 2 factorial, three genotypes and two diets with nine replicates. Colour and pH in Semimembranosus muscle were determined, together with the analyses of the water retention capacity, loss of weight due to cooking, shearing force, and chemical composition in Longissimus dorsi muscle. The factor genotype influenced the chemical composition of meat, with Santa Inês lamb and crossbreed showing the highest protein percentages. The diet with 33.6% fibre content provided meat with higher moisture percentage and lower protein value, and the loss of weight due to cooking and shearing force parameters did not interfere in other variables. In addition, lambs receiving higher fibre content diet produced meat with lower shear force values, having indicated to be more tenderness. Despite these variations, the meat of lambs from all genotypes and under the diets evaluated can be considered of good quality.     

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).     

Effects of untreated and heat-treated canola presscake on milk yield and composition of dairy cows

Five primiparous and five multiparous Holstein cows were used in two Latin square design experiments to determine effects of feeding unheated and heated canola presscake on milk yield and composition, and milk fatty acid concentrations of lactating dairy cows. Five diets that differed in level and source of dietary fat were formulated: a low fat control diet with 30 g kg⁻¹ fat from tallow, an unheated canola presscake supplemented diet (50 g kg⁻¹ fat), a heated canola presscake supplemented diet (50 g kg⁻¹ fat), a high tallow plus unheated canola meal supplemented diet (50 g kg⁻¹ fat), and a high tallow plus heated canola meal supplemented diet (50 g kg⁻¹ fat). In sacco ruminal degradability of heated and unheated canola presscake was compared with that of heated and unheated canola meal in a randomized complete block design using two ruminally fistulated cows. Heat treatment reduced ruminal DM and CP degradability of canola presscake. Multiparous cows fed diets supplemented with heated or unheated canola presscake produced more milk than those fed diets containing similar levels of fat from tallow with heated or unheated canola meal, respectively. High levels of fat from any diet reduced milk fat percentage for cows of either parity. Feeding heated canola products increased milk and milk protein yields in primiparous cows only, but cows of both parities fed diets containing canola presscake produced milk with lower concentrations of C12:0, C14:0, and C16:0 fatty acids than cows fed the canola meal and tallow diets, although concentrations of C18:1 n-9 were unaffected by fat source or level. Feeding canola products to dairy cows can alter milk fatty acid profile, but only primiparous cows have increased productivity as a result of feeding heated, versus unheated, canola presscake.     

Solar-dried citrus pulp as an alternative energy source in lamb diets: Effects on growth and carcass and meat quality

Twenty-seven Italian Merino male lambs, equally divided into three groups, were used to evaluate the effects of the dietary incorporation of citrus pulp dried by exploiting solar energy (solar-dried citrus pulp, SDCP) on growth and carcass and meat quality. The diet consisted of oat hay and concentrate, with a hay/concentrate ratio of 30/70. The concentrates of the SDCP-0, SDCP-30 and SDCP-45 groups were formulated to incorporate 0, 30 and 45% of SDCP, respectively, as partial replacement of cereal grain. The lambs were slaughtered after 80 days of feeding (at 150 days of age) and carcass and some meat quality parameters were measured. No significant differences were found in final live-weights and average daily gains among the groups. Lambs in the SCP-45 group showed impaired (P < 0.001) feed conversion efficiency, lower (P < 0.05) carcass weight and lower (P < 0.05) dressing percentage compared with the other two groups. The majority of SDCP-45 carcasses (88.9%) fell within the bis-grid EU system (light carcasses weighing ≤13 kg), while most SDCP-0 (66.7%) and SDCP-30 (77.8%) carcasses fell within the SEUROP system (heavy carcasses weighing >13 kg). The bis-grid EU carcass classification highlighted how all carcasses produced an ideal meat colour and fatness, while the SEUROP grid carcass classification showed good carcass conformation and optimal fatness in the SDCP-0 and SDCP-30 groups. Carcass compactness was found to be significantly higher (P < 0.05) in groups SDCP-0 and SDCP-30 compared to group SDCP-45. The histological dissection of the pelvic limb evidenced a higher (P < 0.01) adiposity in the SDCP-0 and SDCP-30 groups. Chemical analysis of meat did not differ significantly among the groups. Physical analysis of the meat showed higher (P < 0.05) redness value and higher (P < 0.05) chroma value in the SDCP-0 and SDCP-30 groups. Based on the results of the present study it may be concluded that SDCP can be incorporated in concentrate mixtures for fattening lambs at levels equal to 30% without adverse effects both in growth and slaughter performances as well as in carcass and meat quality and, at this replacement level, it appears also to be economically convenient.     

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.     

Effect of individual and mixed live yeast culture feeding on growth performance,nutrient utilization and microbial crude protein synthesis in lambs

This study investigated effects of feeding three individual, and a mixed, yeast culture (Kluyveromyces marximanus NRRL3234, Saccharomyces cerevisiae NCDC42, Saccharomyces uvarum ATCC9080 all in a 1:1:1, ratio) on growth performance, nutrient utilization and microbial crude protein (CP) synthesis in feedlot lambs during the post-weaning phase of growth. Sixty weaner lambs (90 ± 3.5 d old and 15.9 ± 0.50 kg BW) were fed for 91 d in five equal groups. The control group of lambs received sterilized culture medium while the treatment groups were fed a yeast culture in addition to a ad libitum total mixed ration (TMR). The yeast culture, dosed at 1 ml/kg body weight (BW) had 1.5–2.0 × 10⁹ live cells/ml. Yeast culture supplementation did not influence intake and digestibility of organic matter (OM), CP, neutral detergent fiber (NDF), acid detergent fiber (ADF) and hemicellulose and the metabolizable energy (ME) level of the diets were similar between control and yeast supplemented lambs. Lambs in all groups were in positive N balance, but N intake and N voided in feces and urine, as well as N balance, did not change due to yeast culture supplementation. Urinary allantoin excretion was similar, but purine derivatives absorbed (mM/d) were higher (P<0.05) in yeast culture supplemented lambs. Yeast culture supplementation improved (P<0.05) microbial CP synthesis. Supplementation of SC and mixed yeast improved (P=0.002) BW gain of lambs by 21% and 16% respectively. All yeast culture supplemented lambs had higher feed efficiency in comparison to control lambs. Among the three yeast cultures used, S. cerevisiae had the most potential as a growth promoting feed additive in feedlot lamb production, and it may serve as an alternate to antibiotics and ionophores as a growth promoter of weaner lambs.     

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 dietary inclusion of Ficus infectoria leaves as a protectant of proteins on the performance of lambs

This study examined the effects of dietary inclusion of tanniferous leaves of Ficus infectoria as a protectant of proteins on the performance of lambs. Twenty-four lambs were randomly divided into four groups of six each in a completely randomized block design and fed four iso-nitrogenous supplements formulated to contain 0, 1.0, 1.5 and 2.0% condensed tannins (CT) through dried and ground leaves of F. infectoria. The diets were designated as CT-1.0, CT-1.5 and CT-2.0, respectively, and fed to lambs on a basal diet of wheat straw to meet requirements for maintenance and growth. Blood-biochemical profile was monitored in all the lambs at 0, 45, 90, 135, 180 days of feeding. The average daily growth rate and wool growth for a period of 180 days showed a significant (P < 0.05) increase by the supplementation of CT at 1.5% through F. infectoria leaves. Although addition of CT up to 1.5% in the supplement did not interfere with the nutrient intake or digestibility, a depressing effect on DM, OM and ADF digestibility at 2.0% CT level was apparent without any detrimental affect on intake. Digestible crude protein (DCP) and total digestible nutrients (TDN) values of the composite diets were comparable, except for significantly (P < 0.05) lower TDN (%) in CT-2.0 than the control. Intake of DCP, digestible organic matter and TDN was comparable irrespective of dietary treatments, though lambs under CT-2.0 had significantly (P < 0.05) lower intake as compared to their counterparts given diet CT-1.0. Feeding of CT containing diets particularly at 1.5 and 2.0% levels significantly (P < 0.05) influenced N utilization and improved its retention, however, the microbial protein synthesis as estimated by urinary excretion of purine derivatives was not affected by the dietary treatments. Haematological (haemoglobin and packed cell volume) and biochemical parameters (serum glucose, total protein, albumin, globulin, A:G ratio, alanine aminotransferase and aspartate aminotransferase were similar among the dietary treatments except for significant (P < 0.05) reduction in serum urea concentration of lambs fed 1.5 and 2.0% CT in the supplement. It may be concluded that CT from F. infectoria leaves at 1.5% in supplement could be used as a protectant of proteins for improving the performance of lambs.     

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.     

Introduction of sheep meat breeds in extensive systems: Lamb carcass characteristics

Genotype effects on lamb carcass traits were investigated in a 4-year study aimed at assessing potential benefits from introducing meat breeds into the wool-oriented extensive sheep systems of northeastern Patagonia, Argentina. Five ram [Corriedale: CO; Border Leicester: BL; Île de France: IF; Texel: TX; and synthetic CRIII (25% Merino, 37.5% IF, 37.5% TX)] and 5 dam (CO; synthetic CRIII; BLCO: BL × CO; IFCO: IF × CO; and TXCO: TX × CO) genotypes were represented in the study. Data were collected from 436 male lambs of 9 genotypes (CO × CO, BL × CO, IF × CO, TX × CO, CRIII × CO, CRIII × BLCO, CRIII × IFCO, CRIII × TXCO, and CRIII × CRIII). Hot carcass weights and dressing yields were determined after slaughtering. Carcasses were given conformation and subcutaneous fat scores using the EUROP system [scale varying from E (best) to P (poorest) for conformation, and from 1 (lean) to 5 (overfat) for subcutaneous fat]. Linear measurements of carcass length and width were recorded and carcass compactness indices were calculated from those. Purebred CO acted as a standard for comparisons. On a constant liveweight basis, genotypes CRIII × IFCO and CRIII × CRIII presented higher (P < 0.05) carcass weight and dressing yield than CO × CO and BL × CO. Crossbred and synthetic genotypes showed higher (P < 0.05) carcass width than CO × CO. With the exception of BL × CO the remaining genotypes showed higher (P < 0.05) carcass width/length ratio than CO × CO. The probability that carcasses of crossbred and synthetic lambs presented better conformation than CO × CO was higher than 84%. Carcasses of CRIII × IFCO lambs were given the best conformation scores. The probability that BL × CO carcasses presented higher subcutaneous fat than the remaining genotypes exceeded 79%. Our results indicate significant improvements in carcass conformation arising from crossing. Sheep farmers in extensive systems could take advantage of the higher fatness of BL crossbred lambs to produce light carcasses with adequate fat cover, a crucial industry requirement. Terminal crossbreeding with Île de France, Texel, and CRIII rams could be implemented to improve carcass conformation thus matching market demand for heavy carcasses with limited fat content. Second cross schemes did not improve carcass commercial traits over the best terminal cross or the synthetic CRIII breed.     

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.     

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.     

Influence of level of zilpaterol chlorhydrate supplementation on growth performance and carcass characteristics of feedlot lambs

Forty-eight Pelibuey × Katahdin (38.8 ± 0.67 kg) crossbred male lambs were used in a 32-day feeding trial (four pens per treatment in a randomized complete block design), to evaluate the influence of zilpaterol (β₂-agonist) supplementation level on growth performance and carcass characteristics. Lambs were fed a dry-rolled corn-based finishing diet (3.04 Mcal/kg of ME) supplemented with 0, 0.15, 0.20, or 0.25 mg/kg of live weight d⁻¹ zilpaterol (as zilpaterol chlorhydrate, Zilmax^®, Intervet México, México City). DM intake averaged 1.099 ± 0.042 kg/d and was not affected (P = 0.40) by treatments. Compared with control lambs, zilpaterol supplementation increased gain efficiency (15.8%, P < 0.03), apparent energy retention per unit DMI (10.9%, P = 0.03), and tended to increased daily gain (16%, P < 0.07) and total gain (17.7%, P < 0.08). Zilpaterol supplementation did not affect (P = 0.20) carcass weight, longissimus muscle area (LM), or fat thickness, but increased (2.3%, P = 0.04) carcass dressing percentage and reduced (36%, P < 0.01) kidney-pelvic fat. Increasing level of zilpaterol supplementation increased total weight gain (linear component, P < 0.05), gain:feed (linear component, P < 0.01), and dressing percentage (linear component, P < 0.02), and decreased (linear component, P < 0.01) kidney-pelvic fat. We conclude that zilpaterol supplementation enhances growth performance and dressing percentage in lambs in a manner comparable to that of cattle (greater muscle accretion, reduced body fat). Responses to zilpaterol was optimal when supplemented at 0.20 mg of zilpaterol/kg of live weight d⁻¹.     

Growth performances and carcass traits of Ovin Martinik lambs fed various ratios of tropical forage to concentrate under intensive conditions

Studies were conducted to determine the effects of supplementation upon intake, growth and carcass traits of Ovin Martinik hair sheep. Forty lambs weighing 20 ± 3.7 kg live weight (LW) were reared after weaning in individual pens during a 4-month experimental study. Four supplement levels were compared (10 lambs per treatment): the L0 group received the basal diet (tropical forage 0.75 UFL and 73 PDIN g kg⁻¹ DM, INRA system) without concentrate, the L150, L300 and L600 groups were offered in addition 150, 300 and 600 g day⁻¹ of concentrate (1.15 UFL and 151 PDIN g kg⁻¹ DM), respectively. Intake (5 days a week) and growth patterns (every fortnight) were measured on the 40 lambs, while digestibility measurements (five times throughout the experimental period) were determined on half of the animals fitted with faecal bags and which were slaughtered according to the standard procedure at 33–35 kg live weight for assessment of carcass traits and meat quality.The total dry matter intake (DMI) and digestibility increased (P < 0.01) with the inclusion ratio of the concentrate in the diet: 82 g DM kg W^−0.75 vs. 97 g DM kg W^−0.75 and 65% vs. 73% between the two extreme groups, whereas forage DMI decreased and the forage substitution ratio was calculated to be 0.65. Growth and feed/gain ratios significantly (P < 0.01) improved among the groups L0, L150 and L300, from an average of 134–188 g day⁻¹ and 7.0–5.7, respectively. The differences observed between L300 and L600 were not significant. Carcass weight and dressing out percentages significantly (P < 0.01) increased with the addition of concentrate to the ration: from 13.1 to 15.6 kg and from 39 to 46%, from L0 to L600, respectively. Consequently, the weights of the different cuts of the carcass varied. There was a significant effect of the supplementation level on the accumulation of internal fat tissues: the kidney fat weight increased from 107 to 237 g from the L0 to the L600 groups. No significant effect was observed on the carcass quality scores, the ultimate pH and the colour parameters of the meat.By increasing the nutritional density of the diet, it was possible to obtain well-conformed and heavier carcasses, with no apparent detrimental effect on the quality. The optimal supplement supply with good quality grass would be 300 g day⁻¹ in our conditions.     

Chemical and acidic composition of Longissimus dorsi muscle of Comisana lambs fed with Trifolium subterraneum and Lolium multiflorum

Aim of this study was to evaluate the effects of grazing on Trifolium subterraneum and Lolium multiflorum, as pure or associated crops, on the chemical composition and on the fatty acid profile of the intramuscular lipids of the meat of lambs. Forty Comisana male lambs, on average weighing 13.75 ± 1.90 kg, were divided into four homogenous groups of ten and called, in relation to the diet: group T those grazing on T. subterraneum; Group L on L. multiflorum; Group TL on adjacent monocultures of T. subterraneum and L. multiflorum (66.6 and 33.3% of surface, respectively); Group LT on adjacent monocultures of T. subterraneum and L. multiflorum (33.3 and 66.6% of surface, respectively). Every 10 days, samples of forage species ingested by grazing lambs were collected and analysed. At 90 days of age, with an average live weight of 25.44, 23.44, 24.69 and 24.75 kg for T, L, TL and LT group, respectively, all lambs were slaughtered and a sample of Longissimus dorsi muscle for each animal was collected to study the chemical and acidic composition. No significant differences among the groups were observed for the growth performance and for the chemical composition of the meat. As regards the fatty acid classes, significant differences (P < 0.05) were observed for the monounsaturated fatty acids, which were lower in the group T (35.46%) than those of the groups L (38.24%), TL (38.63%) and LT (38.59%), whereas, significant higher values for the group T were observed for the polyunsaturated fatty acids of the n-3 (4.49%) and n-6 (8.26%) series than those of the n-6 series for group L (6.79%; P < 0.05) and than those of both series for group LT (n-3 = 3.64%; P < 0.05 and n-6 = 6.43%; P < 0.05). The fatty acids that have significantly determined the modifications of the acidic classes were: oleic acid, which showed significant (P < 0.05) lower values in the group T (26.70%) than the levels observed in the groups L (30.33%), TL (30.39%) and LT (30.63%) and the linoleic, linolenic and rumenic acids which were significantly (P < 0.05) higher in the groups T (linoleic = 5.13%; linolenic = 1.97%; rumenic = 0.46%) and TL (linoleic = 4.75%; linolenic = 1.82%; rumenic = 0.41%) than those of the groups L (linoleic = 4.10%; linolenic = 1.52%; rumenic = 0.26%) and LT (linoleic = 3.95%; linolenic = 1.42%; rumenic = 0.33%). These differences could be due to the different dynamic activity of the cellulolytic bacteria in the rumen, related to the different levels of fibrous fractions of the diets. No significant difference was observed for saturated fatty acid, unsaturated/saturated fatty acids ratio and Atherogenic and Thrombogenic indices among the groups, whereas, PUFA/SFA ratio showed significant (P < 0.05) higher value in group T than that in the group LT.T. subterraneum monoculture grazed as monoculture (T) and in mixture with L. multiflorum (66/33, TL) increased the linoleic, linolenic and rumenic acids improving the dietetic-nutritional characteristics of the lamb meat.