甘草提取物对舍饲滩羊增重效果的影响

选择日龄、体重相近,健康状况良好的滩羊羔羊20只,随机分为2组,每组10只,分别为试验组和对照组,且2组羊的初始体重差异不显著(P>0.05)。在试验组羊日粮中添加甘草提取物,研究甘草提取物对滩羊增重效果的影响。结果表明:2组羊的采食量差异显著(P<0.05),试验结束时2组羊的体重、总增重、日增重差异不显著(P>0.05),但试验组各指标均高于对照组,说明添加甘草提取物可以提高滩羊的增重效果。     

The effect of copper on the response of lambs to selenium supplementation when grazing a selenium deficient pasture

Two trials were undertaken with lambs grazing selenium deficient pasture to determine if copper would enhance liveweight and fleece-weight responses to selenium supplementation. In the first trial, lambs given selenium or selenium plus copper gained significantly more weight and had higher fleece-weights after 260 days than did control lambs or lambs given copper alone. Copper given alone or together with selenium had no significant effect on liveweight or fleece-weight when compared with control lambs and lambs that were given selenium alone respectively. This finding was confirmed in a second trial when growth and fleece-weights of selenium and selenium plus copper treated lambs were compared and no significant differences found. In both trials copper significantly raised liver copper levels. In selenium supplemented but not in selenium deficient sheep, copper significantly increased blood selenium levels.     

The effect of chronic non-progressive pneumonia on weight gain of pasturefed lambs

The liveweight gains and carcass weights of 40 lambs grazed under pastoral conditions were compared with those of a similar group with chronic non-progressive pneumonia which had been induced by intranasal inoculation of an aerosol of homogenised pneumonic lung at about 120 days of age. Half the lambs from each group were killed 30 days post-inoculation following rotational grazing on high quality pasture. At this time the pneumonic lambs had a mean liveweight gain of 1.74 kg less than the controls. The remainder were slaughtered at 60 days, when drier conditions prevailed, by which time the difference in mean liveweight had increased to 2.19 kg. During the second period, four of the severely affected lambs lost weight. A significant linear relationship was found between liveweight gain and the extent of the pneumonic lesions which indicated that a reduction of nearly 1 kg/month could be expected for every 10% of the lung surface area affected. Carcass weights were reduced by a mean of 1.5 kg over the 60-day period, 1.39 kg of which occurred in the first 30 days.     

The effect of chronic non-progressive pneumonia on weight gain of pasture-fed lambs

The liveweight gains and carcass weights of 40 lambs grazed under pastoral conditions were compared with those of a similar group with chronic non-progressive pneumonia which had been induced by intranasal inoculation of an aerosol of homogenised pneumonic lung at about 120 days of age. Half the lambs from each group were killed 30 days post-inoculation following rotational grazing on high quality pasture. At this time the pneumonic lambs had a mean liveweight gain of 1.74 kg less than the controls. The remainder were slaughtered at 60 days, when drier conditions prevailed, by which time the difference in mean liveweight had increased to 2.19 kg. During the second period, four of the severely affected lambs lost weight. A significant linear relationship was found between liveweight gain and the extent of the pneumonic lesions which indicated that a reduction of nearly 1 kg/month could be expected for every 10% of the lung surface area affected. Carcass weights were reduced by a mean of 1.5 kg over the 60-day period, 1.39 kg of which occurred in the first 30 days.     

发酵木薯渣替代部分玉米对湖羊生长性能、血清生化指标、屠宰性能和肉品质的影响

本研究旨在探索发酵木薯渣在湖羊日粮中替代部分能量饲料(玉米)的可行性,并确定最佳替代比例。选择48只体重为(18.35±1.39) kg的湖羊公羔,随机分成4组,每组4个重复,每个重复3只羊,分别用发酵木薯渣替代0%(对照组)、20%(A组)、40%(B组)、60%(C组)玉米的日粮进行饲喂,试验期60 d。在试验开始和结束时测定羔羊生长性能,并采集血液样品进行分析,同时在试验结束时进行屠宰试验,测定屠宰性能以及肉品质。研究结果表明,A组湖羊的平均采食量(ADFI)显著高于对照组和B组(P<0.05),日增重(ADG)的变化趋势为A组>B组>对照组(P>0.05),A组和B组的料重比(F/G)有低于对照组的趋势(P>0.05)。而C组湖羊由于腹泻严重,于试验开始2周后将其淘汰。A组的宰前活重、胴体重、肝、瓣胃和肾的重量显著大于对照组和B组(P<0.05),而各组其他内脏器官无显著差异(P>0.05)。各组湖羊的血液生化指标和肉品质均无显著差异(P>0.05)。B组的肉豆蔻酸、棕榈酸等饱和脂肪酸的含量显著低于A组(P<0.05),而B组的十七烷酸和花生酸的含量显著高于A组和对照组(P<0.05),其他种类的脂肪酸无显著差异(P>0.05)。由此可见,利用发酵木薯渣替代20%玉米对湖羊公羔的生长发育和健康无不良影响,且能降低饲料成本,育肥效果最好。因此,将发酵木薯渣作为湖羊的饲料来源是完全可行的。     

Sheep performance under intensive continuous grazing of native grasslands of <Emphasis Type="Italic">Paspalum notatum</Emphasis> and <Emphasis Type="Italic">Axonopus compressus</Emphasis> in the subtropical region of the Highlands of Central Mexico

Liveweight gain was evaluated in tropical Dorper X Pelibuey lambs under intensive continuous grazing of native grasslands dominated by Paspalum notatum (PN) or Axonopus compressus (AC) in the subtropics of Central Mexico. Two trials were undertaken. Trial 1 lasted 12 weeks with 10 lambs (initial weight 18 +/- 2.57 kg, 3 months old) per treatment in 2002, and Trial 2 for 13 weeks with 8 lambs (initial weight 24.0 +/- 2.0 kg, 4 months old) per treatment. Lambs were weighed once per week, and liveweight change was estimated by linear regression over day of the experiment, using individual regression coefficients as unbiased estimates of daily liveweight change; analysed in a random block design. Lambs on Trial 1 gained 0.061 kg/lamb/day on PN and 0.047 kg/lamb/day on AC (P > 0.05) at an overall mean stocking rate of 25 lambs/ha. In Trial 2, liveweight gain was significantly larger in PN (0.060 kg/lamb/day) than on AC (0.043 kg/lamb/day) (P < 0.05), at a mean stocking rate of 21.5 lambs/ha. It is concluded that intensive continuous grazing of native grasslands in the subtropics of the highlands of Central Mexico enables moderate liveweight gains for weaned lambs during the rainy season; with better results in grasslands dominated by Paspalum notatum.     

Role of magnesium in the aetiology of ovine urolithiasis in fattening store lambs and intensively fattened lambs

High dietary levels of magnesium (greater than 2 g/kg drymatter [DM]) have been implicated as the main causal factor of urinary calculi in concentrate-fed lambs. Experiments were performed to try to reproduce this effect of high magnesium (from added calcined magnesite) on the incidence of urolithiasis in lambs. In the first, store lambs were given diets containing magnesium in the following concentrations: A,2.9; B,8.6 g/km DM. Twenty-four blackface lambs were each allocated to A and B and the control group of 160 lambs was fed a combined dried grass/sugar beet pulp pellet and hay ad libitum (diet C). The animals were housed and fed ad libitum until they were killed at an average liveweight of 35 kg. No animals showed clinical signs of urolithiasis and post mortem only a trace of calculous material was recovered from one lamb fed diet A. In the second experiment housed Suffolk and Suffolk cross lambs were fed a starter beginning at three to four weeks old and changed to a finisher at a liveweight of 23 kg. The feeds were either high magnesium starter (5.7) and finisher (6.0) or low magnesium starter (2.3) and finisher (2.8 g/kg DM). Twenty-two single lambs and 32 twins were assigned to both high and low magnesium diets. Lambs fed additional magnesium drank more water/kg DM intake and one of the single lambs showed clinical signs of urolithiasis and was killed. No others showed clinical signs and from the 62 killed there was no post mortem recovery of calculous material.     

Effects of birth weight and postnatal nutrition on neonatal sheep: II. Skeletal muscle growth and development

This study investigated effects of birth weight and postnatal nutrition on growth and development of skeletal muscles in neonatal lambs. Low (L; mean +/- SD 2.289 +/- .341 kg, n = 28) and high (H; 4.840 +/- .446 kg, n = 20) birth weight male Suffolk x (Finnsheep x Dorset) lambs were individually reared on a liquid diet to grow rapidly (ad libitum fed, ADG 337 g, n = 20) or slowly (ADG 150 g, n = 20) from birth to live weights (LW) up to approximately 20 kg. At birth, weight of semitendinosus (ST) muscle in L lambs was 43% that in H lambs; aggregate weights of ST and seven other dissected muscles were similarly reduced. In ST muscle of L lambs, mass of DNA, RNA, and protein were also significantly reduced to levels 67, 60, and 34%, respectively, of those in H lambs. However, myofiber numbers of ST, tibialis caudalis, or soleus muscles did not differ between the L and H birth weight lambs and did not change during postnatal growth. During postnatal rearing, daily accretion rate of dissected muscle was lower in L than in H lambs. Accretion of muscle per kilogram of gain in empty body weight (EBW) was reduced in the slowly grown L lambs compared with their H counterparts, although the difference was less pronounced between the rapidly grown L and H lambs. Throughout the postnatal growth period, ST muscle of L lambs contained less DNA with a higher protein:DNA ratio at any given muscle weight than that of H lambs. Slowly grown lambs had heavier muscles at any given EBW than rapidly grown lambs. Content of DNA and protein:DNA ratio in ST muscle were unaffected by postnatal nutrition, but RNA content and RNA:DNA were greater and protein:RNA was lower at any given muscle weight in rapidly grown lambs. Results suggest that myofiber number in fetal sheep muscles is established before the presumed, negative effects of inadequate fetal nutrient supply on skeletal muscle growth and development become apparent. However, proliferation of myonuclei may be influenced by fetal nutrition in late pregnancy. Reduced myonuclei number in severely growth-retarded newborn lambs may limit the capacity for postnatal growth of skeletal muscles.     

Effect of liveweight and condition score of ewes at mating, and shearing mid-pregnancy, on birthweights and growth rates of twin lambs to weaning

AIMS: To determine the effects of liveweight and condition score of ewes at mating, and shearing mid-pregnancy, on birthweights and growth rates of twin lambs from birth to the time of weaning, and; to determine whether any effect of condition score is independent of liveweight. METHODS: Romney ewes (n=435) which conceived within a 17-day mating period and successfully gave birth to and reared twin lambs to weaning were used. Ewes were managed during pregnancy so that their total liveweight increased at a level equivalent to the expected growth of the conceptuses. Approximately half of the ewes were shorn 70 days after the mid-point of mating, and the remainder were left unshorn, at which time they had 6-months' wool growth. All lambs were weighed within 12 h of birth and again at weaning. RESULTS: There was a significant linear relationship (R2=0.99) between mean group liveweight and condition score of ewes at mating (difference of 7.3 kg per 1.0 unit condition score). Liveweight of ewes at mating had small but significant (p<0.05) positive effects on both birthweights and growth rates of twin lambs to weaning. Ewes that had condition scores of 3.5-4.0 (scale 0-5) at mating gave birth to significantly (p<0.05) lighter lambs than ewes that had condition scores <3.5. The condition score of ewes at mating was positively associated with growth rates of lambs, although this effect was largely explained by variation in the liveweight of ewes at mating. Twin lambs born to ewes shorn mid-pregnancy were significantly (p<0.05) heavier at birth (by 0.4 kg) and at weaning (p<0.05) than those born to unshorn ewes. The heavier weaning weights of lambs born to ewes shorn mid-pregnancy were due to a heavier birthweights rather than increased growth rate. CONCLUSIONS: Liveweight and condition score of ewes at mating had small positive effects on growth rates to weaning of twin lambs. Shearing mid-pregnancy increased birthweights and weaning weights of twin lambs. To achieve high weaning weights of twin lambs, farmers should ensure ewes attain high liveweights and condition scores at mating and shear mid-pregnancy. It is speculated that the effects of liveweight and condition score of ewes at mating on weaning weights of twin lambs would be greater than those observed in the present study under conditions in which nutrition of the dam is below optimum.     

Effect of liveweight and condition score of ewes at mating,and shearing mid-pregnancy,on birthweights and growth rates of twin lambs to weaning

AIMS: To determine the effects of liveweight and condition score of ewes at mating, and shearing mid-pregnancy, on birthweights and growth rates of twin lambs from birth to the time of weaning, and; to determine whether any effect of condition score is independent of liveweight.

METHODS: Romney ewes (n=435) which conceived within a 17-day mating period and successfully gave birth to and reared twin lambs to weaning were used. Ewes were managed during pregnancy so that their total liveweight increased at a level equivalent to the expected growth of the conceptuses. Approximately half of the ewes were shorn 70 days after the mid-point of mating, and the remainder were left unshorn, at which time they had 6-months' wool growth. All lambs were weighed within 12 h of birth and again at weaning.

RESULTS: There was a significant linear relationship (R²=0.99) between mean group liveweight and condition score of ewes at mating (difference of 7.3 kg per 1.0 unit condition score). Liveweight of ewes at mating had small but significant (p<0.05) positive effects on both birthweights and growth rates of twin lambs to weaning. Ewes that had condition scores of 3.5–4.0 (scale 0–5) at mating gave birth to significantly (p<0.05) lighter lambs than ewes that had condition scores <3.5. The condition score of ewes at mating was positively associated with growth rates of lambs, although this effect was largely explained by variation in the liveweight of ewes at mating.

Twin lambs born to ewes shorn mid-pregnancy were significantly (p<0.05) heavier at birth (by 0.4 kg) and at weaning (p<0.05) than those born to unshorn ewes. The heavier weaning weights of lambs born to ewes shorn mid-pregnancy were due to a heavier birthweights rather than increased growth rate.

CONCLUSIONS: Liveweight and condition score of ewes at mating had small positive effects on growth rates to weaning of twin lambs. Shearing mid-pregnancy increased birthweights and weaning weights of twin lambs. To achieve high weaning weights of twin lambs, farmers should ensure ewes attain high liveweights and condition scores at mating and shear mid-pregnancy. It is speculated that the effects of liveweight and condition score of ewes at mating on weaning weights of twin lambs would be greater than those observed in the present study under conditions in which nutrition of the dam is below optimum.     

内蒙古牧区察哈尔羔羊饲粮钙磷适宜水平研究

本试验采用4个不同钙磷水平的饲粮饲喂断奶后察哈尔羔羊,研究钙磷对断奶羔羊生长、钙磷营养消化代谢和排放量、骨骼的影响。选取70日龄健康、体重(16.27±3.33) kg断奶察哈尔羔羊120只(公母各半),随机分成4个组,每组30个重复,每个重复1只羊,分别饲喂4种饲粮,其钙磷含量分别为:Ⅰ组,0.49%、0.28%;Ⅱ组,0.55%、0.32%;Ⅲ组,0.64%、0.47%;Ⅳ组,0.87%、0.70%。饲养试验期65 d,其后,每组选6只羔羊(公母各半),全收粪法进行消化代谢试验。试验结果:1)饲粮钙磷水平对断奶羔羊平均日增重、体尺、干物质采食量和饲粮转化率影响皆不显著(P>0.05);2)血清钙含量Ⅳ组显著高于其他3组,血清碱性磷酸酶Ⅰ组显著高于其他3组(P<0.05);3)Ⅰ组钙表观消化率显著高于其他3组(P<0.05),随饲粮钙磷水平升高羔羊钙磷排放量增加(P<0.05);4)Ⅳ组胫骨灰分含量显著高于Ⅰ组(P<0.05),Ⅰ组跖骨灰分含量显著低于Ⅲ、Ⅳ组(P<0.05),胫骨磷含量Ⅳ组显著高于其他3组(P<0.05);5)冬春季节改变羔羊饲喂模式增加了内蒙古地区草原生态系统中钙磷的输入。综上所述,饲粮钙磷水平升高降低了断奶羔羊的钙表观消化率,显著增加了钙磷的排放量,提高了羔羊骨骼钙磷沉积。在本试验条件下,饲粮钙磷含量分别为0.49%、0.28%,内蒙古地区冬春季断奶羔羊即可获得较好的生长性能。     

Pneumonic lesions in lambs in New Zealand: patterns of prevalence and effects on production

AIM: To describe temporal and spatial patterns of the prevalence of pneumonia in lambs in three regions of New Zealand, and determine effects on liveweight gain. METHODS: A longitudinal study was conducted in 1999- 2000 on 14 commercial sheep farms, five from the Southland region of the South Island, and five from the King Country and four from the Northland regions of the North Island. Pneumonia was known to be a problem in lambs on all farms selected. On each farm, 400 lambs were randomly selected at weaning and allocated at random to one of two groups (Groups I and II). Lambs in both groups were weighed at 4-weekly intervals. The extent of pneumonic lesions in lungs was scored visually at slaughter in 40 randomly selected lambs after each weighing (Group I). Lambs in Group II were selected for slaughter by the farm manager on a commercial basis of liveweight and body condition, then assessed for pneumonic lesions. RESULTS: Prevalence of extensive pneumonic lesions (>/=10% lung surface area affected) increased from December to March from 1.4 to 10.1% lambs in Southland (n=1,917), 1.2 to 25.7% in the King Country (n=1,831), and 4.7 to 21.4% in Northland (n=1,485). Overall, 42.3% of lambs in both groups had pneumonic lesions (n=5,233) and in 15.1% of these, >/=5% of the lung surface area was affected. Daily weight gain in the month prior to slaughter was reduced in lambs for which >/=20% lung surface area was affected in Group I (p<0.05) but not in Group II. CONCLUSIONS: The association between pneumonic lesions and reduced weight gain was highly significant in lambs from Group I, but not from Group II. Thus, pneumonia had a negative impact on weight gain, and selection by farmers of lambs for slaughter counteracted this association in lambs from Group II. CLINICAL RELEVANCE: Pneumonia occurs commonly as a subclinical disease in lambs in New Zealand. It has no public health significance and is not recorded at slaughter plants nor reported to farmer clients. Effects of the disease on daily weight gain of lambs is considerable and costly for lamb producers.     

Relationships among Puberty,Muscle and Fat,and Liveweight Gain during Mating in Young Female Sheep

Greater depths of muscle are associated with better reproductive performance in ewe lambs, but, in adult ewes, reproductive performance also seems to vary with liveweight gain during the mating period. Therefore, in a large field study with Merino ewe lambs, we tested whether the relationships among eye muscle depth (EMD), fat depth (FAT) and reproductive performance depend on liveweight gain during the mating period. We selected lambs with a wide range in phenotypic values for depths of eye muscle (EMD) and fat (FAT) and assigned them to dietary treatments designed to achieve low (LOW, n = 244) or high (HIGH, n = 237) rates of liveweight gain during a 28‐day mating period. The LOW treatment maintained live weight, whereas the HIGH treatment gained 179 ± 3.8 g/day (p < 0.001). From those ewe lambs that attained puberty, first oestrus was detected at live weight 37.8 ± 0.2 kg and age 232 days. The proportion of ewes that attained puberty increased with EMD (p < 0.01). Ewes from the HIGH treatment were more fertile (pregnant ewes per 100 ewes exposed to rams) and had a higher reproductive rate (foetuses in utero per 100 ewes exposed to rams; p < 0.001) than those from the LOW treatment. Fertility and reproductive rate were positively correlated with weight gain during mating as well as live weight at the start of mating, FAT and EMD (p < 0.05 to <0.001). We conclude that faster growth, due to either extra nutrition during mating or higher phenotypic potential for fat and muscle, will increase reproductive performance in ewe lambs mated at 8 months of age.     

Characteristics of lambs fed concentrates or grazed on ryegrass to traditional or heavy slaughter weights. II. Wholesale cuts and tissue accretion

Targhee x Hampshire lambs (average BW 24 +/- 1 kg) were used to determine the effect of finishing on concentrate or by grazing ryegrass forage on slaughter weights of 52 kg (N) or 77 kg (H) on tissue accretion and lamb wholesale cutout. When fed to similar slaughter weights, the wholesale cuts of concentrate-fed lambs were heavier (P < 0.05) than the same cuts from forage-fed lambs; however, when expressed as a percentage of side weight, carcasses of forage-fed lambs had a higher (P < 0.001) percentage of leg than concentrate-fed lambs. Increasing slaughter weight from 52 to 77 kg resulted in a 1-kg increase in loin weight for lambs finished on concentrate and a 0.60-kg increase for lambs finished on forage (diet x slaughter weight, P < 0.03); however, the increased loin weight for lambs finished on concentrate was due largely to increased fat deposition. For lambs slaughtered at 77 kg, those finished on forage had more lean mass in the leg, loin, rack, and shoulder than those finished on concentrate, but lean mass in these cuts did not differ between diets for lambs slaughtered at 52 kg (diet x slaughter weight, P < 0.01). At the normal slaughter weight (52 kg), concentrate-fed lambs had 50% more dissectible fat than forage-fed lambs, whereas at the heavy slaughter weight, a 79% greater amount of dissectible fat was observed for concentrate- vs. forage-fed lambs (diet x slaughter weight, P < 0.001). Lean and fat accretion rates were higher (P < 0.001) for concentrate-fed lambs than for forage-fed lambs. The lean-to-fat ratio of forage-fed lambs was higher (P < 0.001) than that of concentrate-fed lambs; however, forage finishing decreased accretion rates of all tissues compared with concentrate feeding, and these differences between forage and concentrate feeding were magnified at heavier slaughter weights.     

Persistence of carotenoid pigments in the blood of concentrate-finished grazing sheep: its significance for the traceability of grass-feeding

Carotenoid pigments are good biomarkers of grass feeding in sheep. However, grazing lambs are often stall-finished because of grass shortage. We investigated the nature of the carotenoids present in sheep blood and their persistence in this tissue. Four treatments were compared: 1) feeding a concentrate-based diet (n = 10 lambs), 2) grazing followed by a long stall-finishing period (n = 10), 3) grazing followed by a short stall-finishing period (n = 10), and 4) grazing to slaughter weight (n = 10). The concentrate supply was regulated to have similar average daily gain for all treatments. The 40 lambs were allocated to either the grazing or the stall treatments on the basis of their birth date, birth weight, and body weight. The 30 grazing lambs were further allocated to long-stall, short-stall, or grass treatment on the basis of their body weight and plasma carotenoid content. Plasma content of total carotenoids was measured by spectrophotometry during the grazing and the stall periods for all lambs and at slaughter weight for the eight heaviest lambs of each treatment. Analysis of the nature and the concentration of individual carotenoids was performed by HPLC on pasture and stall diets and on blood of grazing lambs. The carotenoid content of the stall diet was 2 to 3% that of the pasture diet. Lutein, zeaxanthin, and beta-carotene accounted for 43 to 58%, 3 to 17%, and 0 to 7% of total plasma carotenoids in grazing lambs, respectively. Two unknown polar carotenoids, expressed in lutein equivalent, accounted for 10 to 22% and 0 to 9% of total carotenoids. Plasma carotenoid content during the grazing and the finishing periods varied among animals (P < 0.001). At slaughter weight, plasma carotenoid content was higher for grass-fed than for stall-fed, long-stall finished, or short-stall finished lambs (P < 0.001), and reliably distinguished grass-fed lambs from all the others. Plasma carotenoid content decreased exponentially with the interval from starting on the stall diet (P < 0.005). The deceleration parameter of the model increased linearly with lamb average daily gain during the stall-finishing period, suggesting that the turnover of carotenoids in the blood may depend on the level of intake of the stall-finishing diet. After 4 to 13 d on the stall diet, depending on the initial plasma carotenoid concentration, plasma carotenoid concentration of previously grazed, stall-finished lambs fell to the values of lambs fed a concentrate diet without grazing. Such a low persistence is of interest for discriminating grazing lambs from stall-finished grazing lambs.     

The effects of diet,slaughter weight and docking on growth,carcass composition and meat quality of fat-tailed Barbarine lambs. A review

This review summarises the main factors that influence meat production and quality in fat-tailed Barbarine (FTB) lambs. As a general feature, FTB lamb's growth is moderate, and the average daily gain ranges between 100 and 350 g. The carcass being relatively fatty, carcass fat content varies from 10% to 32%; white fat and rose meat are often dominant in these carcasses. The meat fatty acid profile of this fat-tailed breed is similar to that of thin-tailed ones, with a prevalence of palmitic, stearic and oleic acids. The order of dissected adipose tissues accumulation, estimated by allometry coefficients, is in agreement with observations in thin-tailed sheep. However, tail fat allometry coefficient is closer to kidney fat values rather than to the subcutaneous one. Concerning effects of feed level, growth of FTB lambs fed silage is higher than those fed oat hay. With moderate concentrate supply, FTB lambs' growth is more pronounced on pasture diet than on the feedlot (FL) diet. Furthermore, at similar slaughter weights, carcasses of lambs fed pasture diet have less tail and carcass fat than those from lambs fed FL diet (5% and 18% vs. 9% and 24% for grazing and FL lambs, respectively). No difference in fat colour, fat firmness or cooked meat flavour is observed between carcasses obtained at different slaughtering weight (i.e. from 25 to 35 kg). The tail docking of FTB improved lambs' growth particularly before weaning. Its effect on carcass composition and fat proportion depends on stage of slaughtering and type of fattening diet. For suckled lambs (4 months), the docking resulted in the lower carcass fat weight (and proportion), while for fattened lambs, carcass composition was similar for all types of lambs. Overall, FTB lambs always grow slower than Noire de Thibar lambs. This is particularly pronounced during the fattening phase. Then, for FTB breed, the possibilities to obtain heavy carcasses are at risks of fat accumulation, 22.8% vs. 14.4% for FTB and Noire de Thibar thin-tailed lambs, respectively. However, the main advantage of FTB breed is that adults are well adapted to food scarcity and may produce lambs even under harsh conditions.     

An evaluation of a modified preventive drenching programme on commercial sheep farms

The effectiveness of a commonly advocated five drench preventive drenching programme in lambs was assessed on nine farms in the Gisborne, Hawkes Bay and Wairarapa districts between December 1983 and March 1985. The productive performance of two groups of preventively drenched lambs was compared with lambs in which parasitism was suppressed by fortnightly drenching from weaning until mid-August 1984. One of the groups received the standard five drench programme commencing at weaning and finishing in March 1984. The other group received six additional 4-weekly drenches, with the last drench in mid-August 1984. All the other lambs on the farms were drenched according to the five drench programme. The availability of infective larvae on pasture and the build-up of parasitic infection in the lambs was monitored. The effects of the different drenching programmes on liveweight and faecal egg counts was followed until March 1985, when the animals were 18 months old. Between March and July 1984 on all nine farms there was a significant depression of growth rates of the standard five drench group when compared with the suppression-drenched group (P<0.01). The mean liveweight difference from December 1983 to July 1984 for all farms was 4.0 kg (P<0.05). Hogget wool weights were significantly depressed (mean difference 0.37 kg, P<0.05). Faecal egg counts rose steadily after the completion of the five drench programme in March, exceeding 1000 eggs per gram on seven farms and 4000 eggs per gram on three of these farms. Trichostrongylus spp. was the major constituent of the winter parasite increase except on one farm when Cooperia spp. succeeded a previous Haemonchus dominance. Two farms had major build-ups of Haemonchus spp., one in early May, the other in June. Six farms salvage-drenched the standard five drench groups. The lambs in the standard drench groups on these farms recovered about half the bodyweight difference between August and March. The mean weight gains to July and wool weights of the modified drench programme groups were reduced slightly compared with the suppression-drenched group (mean liveweight difference 1.4 kg; mean wool weight difference 0.15 kg). No major rises in faecal egg counts occurred. Herbage larval counts exceeded 1000 larvae/kg at some stage on seven farms and, of these, the counts exceeded 4000 larvae/kg on three farms.     

Evaluation of endotoxaemia in the prognosis and treatment of scouring merino lambs

This study looked at measurement of endotoxaemia as a tool in determining prognosis and probable response to treatment in scouring lambs. One hundred eighty-three lambs in the first 15-20 days of life, from eight Merino sheep farms located in the region of La Serena, south-west Spain, were used in this experiment. Scouring and normal/control lambs were selected following a clinical examination, the scouring group was further divided into subgroups, specifically those that did or did not survive 72 h following treatment. At the time of the clinical examination, faecal and blood samples were taken. Faecal culture and commercial faecal antigen tests for detection of enteropathogens in faeces and serum endotoxin measurement using chromogenic lymulus amoebocyte lysate (LAL) were carried out. Scouring lambs received 0.07 mg/kg liveweight halofuginone once a day for 3 days, a single oral dose of 0.20 mg/kg liveweight of spectinomycin and oral rehydration fluid. The pathogens isolated were Cryptosporidium spp. and Escherichia coli. The case fatality rate was 51% in the scouring lambs. Postmortem findings were consistent with enterotoxigenic E. coli infection. The concentration of endotoxin was 0.18 +/- 0.12 ng/ml in the control group, 0.35 +/- 0.17 ng/ml in the surviving lambs and 0.46 +/- 0.14 ng/ml in the non-surviving lambs. Significant differences between groups were found. Case fatality rate of the scouring lambs with endotoxaemia below 0.30 ng/ml was 0%, while it was 100% above 0.50 ng/ml. These results may be utilized as a prognostic indicator in lambs affected by E. coli and Cryptosporidium that will help aid in decision-making as to whether to treat a lamb or not based on its chances of survival.     

The effect of dietary protein on the pathogenesis of acute ovine haemonchosis

Two experiments were conducted to examine the ifluence of dietary proteins on parasite establishment and pathogenesis in Finn Dorset/Dorset Horn lambs infected with Haemonchus contortus. The lambs were introduced to high (169 g) or low (88 g crude protein (CP) kg⁻¹ dry matter (DM)) protein diets at 3 months of age and infected 1 month later with 350 larvae kg⁻¹ body weight (BW). Blood and faecal smaples were collected for analysis and body weights recorded weekly. In the first experiments some of the infected lambs were killed 6 weeks after infection and the remainder 5 weeks later. In the second experimental all the infected lambs were killed 4 weeks after infection.

The results showed that lambs on a low protein diet were less able to withstand the pathogenic effects of infection with 350 H. contortus larvae kg⁻¹ BW than lambs given the higher protein diet. Thus mortality was greater in the low protein group and adverse clinical signs, such as inappetance, weight loss and oedema were osbserved more frequently. This group also had a more severe anaemia, hypoproteinaemia and hypoalbuminnaemia than the high protein group. In contrast, faecal egg counts, total daily faecal egg output and worm burdens were similar in all groups of infected lambs, indicating that the diets did not influence parasite establishment.     

Field studies of the immunisation of lambs with drug-abbreviated infections of Trichostrongylus colubriformis and Ostertagia circumcincta

Fifty, 5-6 month-old lambs were randomly allocated to five equal groups. Three groups of lambs were immunised by three oxfendazole-abbreviated (artificial) infections of Trichostrongylus colubriformis and Ostertagia circumcincta. Group 1 was immunised with a high dose of larvae, Group 2 with a medium dose and Group 3 with a low dose. A fourth group was treated with oxfendazole only and a fifth group was not treated (control). All groups were grazed together on pasture naturally contaminated with nematode larvae. Immunisation significantly reduced the number of eggs per gram of faeces in all three groups, but the lowest faecal egg count was seen in Group 3 (immunised with the lowest number of larvae). Significantly better liveweight gains and wool weight were observed in Group 2 animals than in the control group. Of all anthelmintic-treated animals, only Group 1 lambs did not have a significantly lower dag weight than controls.