首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 109 毫秒
1.
枯草期选甘肃高山细毛羊成年母羊180只,后备母羊38只,羔羊40只,进行为期171 d的放牧与舍饲对比试验。结果表明:试验组(暖棚舍饲)平均每只成年母羊、后备母羊和羔羊体质量分别增加5.1、9.8和6.9 kg,增幅为:11.72%、30.81%和32.86%;对照组(放牧)每只成年母羊、后备母羊和羔羊体质量分别平均下降7.3、5.0和1.0 kg;试验末,试验组成年母羊和后备母羊体质量极显著高于对照组(P0.01),试验组羔羊体质量显著高于对照组(P0.05)。羊毛长度试验组成年母羊、后备母羊和羔羊羊毛每只分别平均增长3.9、3.8和2.7 cm,试验组成年母羊和后备母羊比对照组提高10.4%和16.0%,羔羊比对照组降低11.2%,试验组和对照组差异不显著(P0.05)。试验组各年龄段产羊毛量分别达5.24、4.56和3.79 kg,比对照组分别提高60.24%、73.38%和49.80%,差异极显著(P0.01)。试验组纯收入分别为成年母羊5.35元/只,后备母羊45.65元/只,羔羊59.57元/只,对照组由于掉膘损失严重,成年母羊和后备母羊分别损失28.32和13.05元/只,羔羊收益29.3元/只。  相似文献   

2.
The pre-weaning production of ewes and lambs in spring on pastures grazed during the previous autumn and early winter by either weaner sheep, adult sheep, or cattle was investigated together with estimating the benefits of pre- and post-lambing drenches to ewes. These treatments were compared with one in which parasitism was uncontrolled in ewes lambing on pastures grazed previously by untreated weaner sheep, and another where parasitism was suppressed by 2-weekly drenching of the weaner sheep and also of the ewes and their lambs. Prior grazing by cattle effectively eliminated infection of pastures with intestinal Trichostrongylus and Nematodirus spp, but less so for Ostertagia spp. Worthwhile reductions in contamination were also achieved by grazing by adult sheep compared with grazing by undrenched weaners. Despite differences in the parasitological status of the pastures, there were no indications that pre-weaning growth rates of lambs were affected. However, wool growth in ewes was reduced by 10 to 20% by parasite infection. Wool growth of ewes on pastures grazed by cattle during the pre-experimental period exceeded that on any other treatment, and was significantly greater than that of ewes on pastures grazed by undrenched weaners. There was no production benefit in giving a pre-lambing drench to ewes on plots contaminated by weaners, or in giving the additional post-lambing drench to ewes grazing on plots contaminated by weaners, adult sheep or cattle.  相似文献   

3.
An m:n matched case–control study was conducted to identify risk factors for ovine clinical mastitis (CM). Data were from a national sheep registry and only ewes that lambed in the spring of 2004 were included. Eligible cases (n = 2857) and controls (n = 76,716) from 1056 flocks of meat sheep were matched on flock and conditional logistic regression was used for analysis of the data. CM risk was associated with age of the ewe and whether or not assistance at lambing was needed owing to dystocia; however, the effects of both these factors were modified by the number of lambs born. In ewes with 1 lamb, increasing age was associated with increased odds of CM (OR = 1.2 for each 1-year increase), while only a slight numerical increase in the odds was observed in ewes with >1 lamb. Dystocia was associated with increased odds of CM in ewes with 1 lamb (OR = 1.7) or 2 lambs (OR = 1.4), while no association was observed in ewes with >2 lambs. The odds of CM increased markedly with increasing number of lambs born to the ewe. For example, odds for 2-year-old ewes without dystocia were 6.7 times greater for those with >3 lambs than for those with 1 lamb. Compared with ewes of old Norwegian breeds, ewes of other breeds were more likely to experience CM (OR = 1.7). Ewes treated for CM at least once during the preceding 3 years had 4.0 times greater odds of CM compared with ewes without a CM history. It is likely that the effect estimates from this study, which are adjusted for breed and unaffected by inter-flock variations, are valid also for other meat sheep populations.  相似文献   

4.
In a study of the relationship between pasture rotation in Illinois and acquisition of nematodes (mostly Haemonchus contortus) and body weight gains by lambs grazing with their ewes, 2 pasture rotation systems were tested. (1) Lambs and ewes were rotated through a series of 12 alfalfa-bromegrass-lespedeza pastures, each pasture being grazed for 3 to 4 days and rested for 5.5 weeks; 4 complete rotations were done during a 168-day grazing season. (2) Lambs and ewes were moved every 2 days, and 3 complete rotations of 50, 42, and 54 days, respectively, were done during the 146-day grazing season. The lambs under rotation had more nematodes and gained less weight than nonrotated control lambs, although rotation increased the amount of pasturage. Rotation is not recommended to control nematode parasitism of sheep in Illinois.  相似文献   

5.
Romanov X Rasa Aragonesa ewes rearing twins and kept on pasture at a mean stocking density of 35 ewes ha-1 were used to study the epidemiology of parasitic gastro-enteritis under an intensive grazing system on irrigated land in the northeast of Spain. Measurements were made of the population of infective larvae on the pasture, level of serum pepsinogen, faecal worm eggs in ewes and lambs, and lamb growth rates. In addition, postmortem worm counts from "indicator" lambs were used to establish the level of infection at each rotational grazing cycle. Two generations of parasites were identified in the experiment. One of them, derived from the eggs deposited the previous autumn, gave rise to the first infection of the animals in March and April. This was responsible for the first outbreak of parasitism in the lambs. This was indicated by an increase in serum pepsinogen levels, the appearance of diarrhoea and a significant decrease in lamb growth rates. Ostertagia spp., Nematodirus spp. and Trichostrongylus spp. were present. The second generation, which appeared during May, was derived from the eggs of the previous generation and gave rise to an outbreak of parasitism in the lambs at the beginning of May and the middle of June. Haemonchus spp. and Chabertia ovina were present. Under the conditions of this experiment, the overwintering larvae have an important epidemiological significance as the gastro-intestinal nematodes are one of the main limiting factors for developing intensive sheep production systems.  相似文献   

6.
In rain-fed cereal-producing areas of Morocco, stubble and straw from barley and wheat and forage grazed from fallow lands are important feeds for sheep. Supplementation to maintain BW of ewes pregnant while grazing stubble, methods to improve utilization of straw, annual forage legumes to complement grazing of fallow land, and by-product feeds in diets for weaned lambs have been tested in collaborative research trials. Pregnant ewes grazing cereal stubble for 10 to 12 wk at a modest stocking rate and unsupplemented, or at a heavier stocking rate and supplemented after 5 wk, gained about 3 kg; most of the gain occurred in wk 1 to 4 due to intake of residual scattered grain. Following the stubble-grazing period (coincident with late gestation), straw plus an energy supplement alone resulted in low lamb birth weight and survivability. Urea treatment increased N content of straw and holds potential. After the onset of winter rains, self-reseeding annual legume (Medicago spp.) pastures allowed lactating Timahdit ewes to gain 4 kg during 90 d postpartum. Their suckling lambs gained 260 g/d, thus doubling the weight of lamb weaned per ewe compared with those grazing unimproved fallow. Confined growing lambs fed diets with 40% sugarbeet pulp or 20% carob meal gained more than 200 g/d, reducing the time needed to reach market weight. These results demonstrate that marked improvements in performance and efficiency of sheep in Mediterranean rain-fed cereal/livestock systems are possible using locally available resources.  相似文献   

7.
Pregnant St. Croix White and Barbados Blackbelly hair sheep ewes were used to evaluate the effect of supplemental nutrition around the time of lambing on ewe and lamb performance during the dry and wet seasons on St. Croix. Beginning 14 d before expected day of lambing (d 0) and for 21 d postpartum, one group of ewes was fed a pelleted supplement in addition to grazing guinea grass pasture (FEED). Other ewes in the flock grazed pasture only (CONTROL). This study was conducted during the dry season (June through September; FEED n = 14 and CONTROL n = 15) and during the wet season the next year (October through January; FEED n = 11 and CONTROL n = 12). The 24-h milk production of each ewe was measured on d 7, 21, 35, 49, and 63. Ewes were exposed to sterile rams equipped with marking harnesses to detect estrus during the postpartum period. The FEED ewes lost less weight postpartum during both seasons (P < 0.0001) and had higher milk production (P < 0.009) than CONTROL ewes during the dry season. During the dry season, the time to the first postpartum estrus did not differ (P > 0.10) between FEED and CONTROL ewes (46.9 +/- 2.7 vs 52.9 +/- 2.6 d, respectively). During the wet season, the time to first postpartum estrus was less (P < 0.07) in FEED than in CONTROL ewes (33.0 +/- 3.1 vs 41.1 +/- 2.9 d, respectively). The FEED ewes had higher lamb birth weight (P < 0.04) and weaning weight (P < 0.05) than CONTROL ewes (3.2 +/- 0.1 and 12.2 +/- 0.5 vs 2.9 +/- 0.1 and 10.9 +/- 0.5 kg, respectively) during the dry season. In the wet season, lamb birth weight and weaning weight were similar (P > 0.10) between FEED and CONTROL (3.2 +/- 0.1 and 15.5 +/- 0.7 vs 3.1 +/- 0.1 and 15.3 +/- 0.6 kg, respectively). Lambs born during the wet season had higher (P < 0.0001) ADG than lambs born during the dry season (194.4 +/- 5.9 vs 127.7 +/- 4.7 g/d, respectively). Strategic nutritional supplementation of hair sheep ewes may provide a method for increasing the weight of lambs produced during the dry season in the tropics, but it does not seem to be beneficial during the wet season.  相似文献   

8.
Effects of genetic and environmental factors on pre-weaning and post-weaning growth were studied in West African crossbred sheep. Effects of lamb genotype (7/8 Sahelian–1/8 Djallonké, 3/4 Sahelian–1/4 Djallonké and 1/2 Sahelian–1/2 Djallonké; hereafter denoted 7/8Sa, 3/4Sa and 1/2Sa, respectively), parity, type of birth, sex of lamb and year-season of lambing on birth weight, weaning weight, 8-month weight and pre- and post-weaning growth rates were determined. At birth 7/8Sa and 3/4Sa lambs were heavier (p<0.01) than 1/2Sa lambs. Lambs born to first-parity ewes were lighter (p<0.01) at birth than lambs of older ewes. At weaning and 8 months of age, lambs born to fourth-parity ewes were heavier (p<0.05) than those born to ewes of the other parities. Parity did not have any significant effects on pre-weaning growth rate. Lambs born in the rainy season of 2001 were significantly heavier at birth and at 8 months of age than those born in the dry season of 2001/02, but there was no difference between the two groups at weaning. Pre-weaning growth rate was significantly faster in lambs born in the dry season of 2001/02 but the reverse was true for post-weaning growth rate.  相似文献   

9.
Observations of behaviour at parturition of prolific Booroola Merinos were recorded for 48 single-, 77 twin-, 56 triplet- and 14 quadruplet-bearing ewes. Average lamb birthweight decreased as litter size increased. Single lambs were on average 2 kg heavier than quadruplet lambs. Within twin and triplet litters the period of abdominal straining during labour was significantly shorter for later-born lambs than for the first-born lamb. Single-born lambs were presented longer at the ewe's vulva than lambs from other litters. The first-born of twins was presented longer at the ewe's vulva than the second-born lamb. Ewes 2 years of age were slower to stand after birth and to begin to groom lambs than adult ewes. The ewe was not selective in grooming members of a litter. The first-born lamb of single and twin litter sizes was quicker to stand and suck than the first-born lamb of triplet and quadruplet litters. The second-born lamb of twins was quicker to suck than the second-born of other litter sizes. Birth order did not affect the time taken to suck. Regardless of litter size, heavier lambs were quicker to stand and suck resulting in a greater chance of survival, and an increase of 1 kg in birthweight resulted in a 28% increase in survival. Survival of lambs was significantly affected by their behaviour after adjustment for birthweight. With an increase of 1 min in the intervals from delivery to when the lamb first attempts to stand, stands or attempts to find the udder its chances of survival decreased by about 1%. It was concluded that birthweight was the major component affecting lamb survival in prolific Booroola Merino sheep.  相似文献   

10.
Helminth infection acquired by lambs grazing on pastures fertilised either by urban sewage sludge or cattle slurry were studied in temperate Central Western France. The aim was to assess the risk of larval cestodoses in lambs after sewage application and of digestive tract nematode infection following the slurry application. Twenty-six sheep were allocated on two paddocks of 0.7 ha, one fertilised with sludge and the other with cattle slurry. The delay between application and actual grazing was 6 weeks; grazing on these paddocks extended from mid July to beginning of November 2002. The herbage biomass was slightly increased in the sludge paddock but it did not result in an increase of lamb live weight, compared with the slurry paddock. The lambs did not acquire cysticercosis or any other larval cestodoses in the sewage sludge group and only very limited infections with Cooperia spp. and Nematodirus spp. were observed in the slurry group. It was concluded that in our conditions the helminth risk was extremely low and was not a cause of restriction of the use of these biowastes.  相似文献   

11.
Abstract

The effect of urine and dung deposition on the patch grazing patterns of cattle and sheep in the Southern Tall Grassveld was investigated using an experiment with four treatments, viz. artificial urine, fresh cattle dung, fresh sheep dung, and a control. Cattle and sheep preferentially grazed the sward surrounding and within urine deposits for six months after deposition. Cattle rejected herbage from both cattle and sheep dung patches for six months after deposition. Sheep initially rejected the herbage from cattle dung patches, but their grazing patterns were no longer affected at six months after deposition. Sheep grazing tended not to be influenced by sheep dung. Urine deposition may consequently be an important factor in patch initiation and patch development.  相似文献   

12.
藏系绵羊在产羔后分为4组,进行为期90天的补饲试验,结果:试验1组只均日补饲优质青干草0.5 kg,母羊和羔羊的增重分别为1.57kg和5.29kg;试验2组只均日补饲精料0.25kg,母羊和羔羊的增重分别为2.36 kg和7.9kg;试验3组只均日补饲精料0.5kg,母羊和羔羊的增重分别为4.25 kg和10.02kg;试验4组只均日补饲营养添砖0.15kg,母羊和羔羊的增重分别为1.7kg和6.51kg。4个试验组均达到了母羊保膘和羔羊成活的目的。其中,第3组母羊和羔羊的增重最高,饲料成本也最高;第1组母羊和羔羊的增重最少,但补饲成本最低。  相似文献   

13.
The effect of forward (F) and lateral (L) creep grazing, as two possible management alternatives of intensive production systems, on the gastro-intestinal nematode epidemiology of ewes and lambs was studied. Two groups of Romanov x Rasa Aragonesa ewes rearing twins and maintained on an autumn-contaminated pasture at a mean stocking density of 35 ewes ha-1, were used. Measurements were made of the population of infective larvae on the pasture, level of serum pepsinogen, worm eggs in faeces of ewes and lambs, and lambs' growth rate. In addition, post-mortem worm counts from 'indicator' lambs were used to establish the level of infection at each rotational grazing cycle. Two different waves of nematode infection were identified. In both treatments, the over-wintering larvae were responsible for the first outbreak of parasitism which was particularly important for lambs on Treatment F. The second wave of infection apparently came up with several overlapped L3 generations and had different effects on the animals of each group. While early pasture contamination was suffered by the lambs of Treatment F, lambs on Treatment L were not seriously affected until the end of the third grazing cycle (end of May). The different grazing behaviour of lambs in both treatments appeared to be related to the outbreak of parasitism in lambs. The general pattern of liveweight gains was similar for both groups of animals. However, during the first 90 days on pasture lamb growth rate under Treatment L (193 g day-1) was significantly higher than that under Treatment F (164 g day-1). The serum pepsinogen values, worm burdens and liveweight gains indicate that under intensive systems where lateral creep grazing is allowed for lambs, the level of parasite infection is maintained within acceptable limits for the first 90 days on pasture with lambs' growth rate close to their potential. However, the parasitic consequences of grazing under a forward creeping system indicate that anthelmintic drenchings should be used at lambing and at 3-week intervals thereafter during the first 42 days on pasture, after which the risk of contamination from the over-wintering population is over.  相似文献   

14.
A three-year survey (1997-99) was carried out on organically reared sheep flocks throughout Sweden. The aim was to determine the prevalence and intensity of nematode infections and to establish relationships between sheep management practices and parasite infections. Faecal samples from ewes and lambs were collected from 152 organic flocks around lambing-time and during the grazing-period for analysis. Results were compared with the different management practices that farmers use to prevent parasitism in their flocks. A high proportion of the flocks was infected with nematodes. The most prevalent species were Haemonchus contortus, Teladorsagia circumeincta, Trichostrongylus axei. T. colubriformis and Chabertia ovina and infections progressively increased during summer in lambs grazing on permanent pastures. Severity of parasitic infection in lambs was highly dependent on egg output from the ewes. H. contortus was found in 37% of the flocks, even at latitudes approximating the Polar Circle. Nematodirus battus was recorded for the first time in Sweden during the course of this study. Lambs turned out onto permanent pasture showed higher nematode faecal egg counts (epg) than lambs that had grazed on pastures, which had not carried sheep the previous year. This beneficial effect of lambs grazing non-infected pastures persisted if the ewes were treated with an anthelmintic before turn-out and if the lambs were kept on pastures of low infectivity after weaning. In lambs, the prevalence and the magnitude of their egg counts were higher during autumn in flocks where lambs were slaughtered after 8 months of age, compared with flocks where all lambs were slaughtered before this age. These results will be used in providing advice to farmers of ways to modify their flock management in order to minimise the use of anthelmintics, but at the same time efficiently produce prime lambs.  相似文献   

15.
The objective of the study was to investigate reservoirs and transmission of S. aureus in ewes and lambs in 3 meat sheep flocks. Repeated sampling of milk, teat skin, nasal- and vaginal mucous membranes was performed and samples were analysed for S. aureus. For comparison, samples were also collected from cows and young heifers in 3 dairy cattle herds. Selected isolates were compared by pulsed-field gel electrophoresis (PFGE). S. aureus was detected in 8 (1.5%) of 520 milk samples from ewes and in 38 (6.4%) of 588 milk samples from cows. From body site swabs, S. aureus was found in 394 (32.6%) of 1208 samples from sheep and in 67 (16.0%) of 420 samples from cattle. The proportion of S. aureus-positive nasal swabs from ewes and cows were 56.7% and 13.9%, respectively. From lambs, 58.2% of the nasal swabs were S. aureus-positive. In each flock, one S. aureus pulsotype predominated. Identical S. aureus pulsotypes were found in milk and from body sites. Paired S. aureus isolates from the nasal cavity of (i) ewes and their lambs, (ii) twins and (iii) from repeated swabs of individual ewes were compared by PFGE, and in the majority of cases the two isolates were identical. The results contribute new knowledge indicating frequent transmission of S. aureus between the dam and her lambs and within animals in a flock. In contrast to cattle, S. aureus is frequently present in the nose of sheep which may represent the primary reservoir of S. aureus in sheep flocks.  相似文献   

16.
Previous experiments have shown that mixed or conjoint grazing, when two or more animal species are grazed together, can lead to improved performance of one or more of the species and a higher total output per unit area. Sequential grazing systems, when different animal species graze an area in succession, also have the potential to improve productivity. This experiment directly compared these two approaches for integrating the grazing of cattle and sheep when pastured on improved permanent pasture. Four treatments were compared: 1) sheep only from May to October (S/S); 2) cattle only from May to July followed by sheep only from August to October (C/S); 3) cattle and sheep from May to July, sheep only for the rest of the growing season (C + S/S); and 4) cattle and sheep from May to October (C + S/C + S). Each treatment was replicated three times. From May until weaning at the end of July the plots were grazed by steers and ewes and lambs, and from weaning until October by steers and lambs. Sward heights were maintained at 6 cm using a “put and take” stocking system. Animal performance and sward composition data were collected during three growing seasons, 2001–2003. During the pre-weaning period lambs grazing plots which were grazed only by sheep had significantly poorer growth rates than those grazing plots where there was mixed grazing. Lambs grazing the sheep only plots also had lower liveweight gain during the post-weaning period, with the highest growth rates being recorded on the C + S/C + S treatment. Carrying capacity and total liveweight gain per unit area post-weaning were also consistently higher for the C + S/C + S treatment, while carrying capacity pre-weaning was highest for the C/S treatment. Measurements of clover content in the grazed horizon and botanical separation of material from quadrat cuts indicated that even under relatively controlled conditions choice of grazing system can influence sward composition. However, there was no clear link between any single sward change and the growth of the animals, indicating that the improved performance of cattle and sheep under mixed grazing is the result of a combination of factors, rather than a response to a particular sward parameter.  相似文献   

17.
The persistent effect of doramectin injectable against gastrointestinal nematodes was investigated in a controlled field study with 70 sheep kept on alpine pastures in Switzerland. After grazing on home pastures for four weeks 50 lambs and 20 ewes were allocated to two equal groups according to age and body weight. At turnout to alpine pasture in June doramectin (0.3 mg/kg) was administered by intramuscular injection to 25 lambs and 10 ewes (Group D), whereas control sheep (Group K) remained untreated. Animals of both groups were kept on separate pastures (altitude: 1100 m) and were rotated between three paddocks during a total grazing period of 13 weeks. After doramectin treatment faecal examinations of Group D sheep showed a marked reduction of the trichostrongyle egg output which remained close to zero for eight weeks. During this period serum pepsinogen levels did not indicate the presence of a substantial immature worm burden in the abomasal mucosa. In the last five weeks of the alpine grazing period the trichostrongyle egg counts increased markedly in the lambs of Group D. Lambs of the control group developed moderate-to-high Haemonchus-infections, and eight animals of this group had to be treated with anthelmintics. Lambs of Group D had gained significantly (P < 0.05) more weight eight weeks after turnout whereas the mean bodyweight stagnated during the last five weeks of the grazing period. The results indicate, that the single administration of 0.3 mg/kg doramectin to lambs and ewes provided good protection against severe infections with gastrointestinal nematodes for a period of approximately eight weeks.  相似文献   

18.
A commercial fertiliser, consisting of a poorly soluble barium selenate core with a coating of highly soluble sodium selenite, was evaluated in 2 trials for the provision of selenium (Se) to grazing sheep. The fertiliser was administered at a level of 1 kg per hectare to 3 of 6 kikuyu paddocks during 1995 and 1996 in Trial 1, while the other paddocks were left untreated. The Se status of SA mutton merino ram lambs, as reflected by whole blood, liver and kidney Se concentrations, was elevated (P < 0.01) for at least 5 months after application of the fertiliser. Whole blood and liver Se concentrations of animals grazing unfertilised control paddocks were indicative of a subclinical Se deficiency at times (<100 ng Se/ml whole blood and <300 microg Se/kg liver dry matter). In Trial 2, 4 of 7 paddocks on which an oat fodder crop was established were treated with the Se fertiliser during 1995 and 1997. The remaining 3 paddocks were left unfertilised as controls. Groups of 10-15 pregnant SA mutton merino ewes were introduced to these paddocks within 2 weeks of parturition. These ewes and their progeny utilised these paddocks for a mean (+/- SD) period of 41 +/- 8 days after parturition. The whole blood Se concentrations of these ewes and their offspring were elevated (P < 0.01) relative to their contemporaries utilising control paddocks. No suggestion of a subclinical Se deficiency was discernible in animals grazing control paddocks, although whole blood Se levels approached 100 ng Se/ml during 1997. The application of Se fertiliser did not result in improvements in ewe reproduction or lamb growth. There was a suggestion of an improvement (P = 0.21) in mean (+/- SE) lamb survival on paddocks receiving Se fertiliser compared to control paddocks (71.5 +/- 4.6% vs 62.2 +/- 5.3% respectively).  相似文献   

19.
A total of 147 ewes, 4 rams and 188 lambs of their progeny of the Djallonké breed of sheep were used to study the factors affecting reproductive and growth traits and the causes of lamb mortality. Data on ewes were collected during a 12-month period, while those on the lambs born to 123 of the ewes were collected until they were 12 months of age. The average fertility and abortion rates were 0.84 and 0.09. The fertility rate increased and the abortion rate decreased with increasing age of the ewes (p<0.05). The number of lambs born per ewe joined, litter weight at birth per ewe joined and litter weight at weaning per ewe joined were 1.28, 3.5 kg and 17 kg, respectively. The average numbers of lambs born per ewe, lambs born alive per ewe, lambs born dead per ewe and lambs per ewe that died between birth and weaning were 1.53, 1.43, 0.03 and 0.3, respectively. The age of the ewes significantly (p<0.05) affected all these traits except the number of dead lambs and the index of fertility (94%). The age of the ewes significantly (p<0.05) affected the birth weight and the weight at 6 and 12 months of age, whereas the lambing season significantly (p<0.05) affected all the growth traits studied. The type of birth was the most important source of variation in body weights of lambs. Sex had no significant (p>0.05) effect on the growth traits studied. The complex `starvation–bad management–light body weight at birth' caused 48% of the lamb mortality between birth and weaning, while diarrhoea, pneumonia and internal and external parasites caused approximately 52% of the lamb mortality over the same period. The seasonal raw mortality rate of the lambs before weaning was highest in the humid season.  相似文献   

20.
The difference in susceptibility to alveld between lambs and adult sheep may be caused by differences in the microsomal enzyme activities in their livers. There was no difference in NADPH-cytochrome c reductase or 7-ethoxyresorufin-O-deethylase (EROD) activity between ewes, control lambs and phenobarbitone-dosed lambs 3 weeks after dosing ceased. However, aldrin epoxidase activity was at that time significantly highest in the phenobarbitone-dosed lambs and significantly lowest in the ewes. The liver cytosolic glutathione transferase activity was significantly highest in the ewes and significantly lowest in the control lambs at the same time.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号