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1.
Lifetime production of first-generation 1/4 and 1/2 Finnsheep crossbred ewes from Rambouillet (R), Targhee (T) and Columbia (C) dams was compared with that from randomly selected purebred R, T and C ewes. All 1,190 ewes, representing nine breed groups, were managed under range conditions and mated annually to Suffolk rams. Lifetime production was evaluated as the total lamb and total wool production per ewe from the time each entered the breeding flock at 7 mo of age through the period each remained in the flock (potentially seven producing years). Culling was for debilitating unsoundness only. The study was designed to determine the average lifetime production per breed group as affected by natural ewe attrition. Orphan-reared lambs were not included in lamb production nor were foster lambs, except those actually born in and reared by the groups. Differences among pooled breed groups (1/4 Finns, 1/2 Finns and purebreds) were not significant for average final age in the flock (5.1, 5.1 and 4.9 yr, respectively), but differences were significant (P less than .01) for lifetime lamb and wool production. Average lifetime fleece weights of 1/4 and 1/2 Finn ewes were only 95 and 82% as high, respectively, as those of purebreds. However, 1/4 and 1/2 Finn ewes had 34 and 46%, respectively, higher numbers of lambs weaned (at 130 d) and 30 and 38% higher total weight of lamb weaned than purebreds.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

2.
Objectives of this study were to estimate the magnitude of the effects of various factors associated with ewes and their ram lamb mates on fertility, prolificacy, lamb survival, lamb weaning weight and ewe productivity and to estimate the heritability and repeatability of each trait. Records from 731 ewe-years, 75 ram lamb sires and 616 lambs born from the University of Illinois Rambouillet flock were used. Ewes mated to single-born ram lambs had higher fertility rates (P less than .01), gave birth to lambs with higher survival rates (P less than .01), weaned lighter (P less than .05) individual lambs but weaned more weight of lamb per ewe exposed (P less than .01) than ewes mated to multiple-born ram lambs. Ram lamb breeding weight, ram lamb scrotal circumference, ewe breeding weight and ewe age had relatively large and positive effects on the composite trait of weight of lamb weaned per ewe exposed and significant effects on a number of the component traits. Heritability and repeatability estimates were, respectively, as follows: fertility, 3%, 3%; prolificacy, 34%, 19%; lamb survival, 15%, 8%; lamb weaning weight, 7%, 36%; and ewe productivity, 27%, 10%.  相似文献   

3.
Scrapie is one of several transmissible spongiform encephalopathies of livestock. Disease susceptibility is linked to polymorphisms in the normal prion protein gene that encodes the mammalian prion precursor. Codon 171 of this gene is a major determinant of scrapie susceptibility. Selection for arginine (R) at codon 171 is encouraged by the USDA to decrease the incidence of scrapie. Objectives of this study were to determine the frequency of R allele variants at codon 171 in a sample of sheep from five breeds (Columbia, Hampshire, Rambouillet, Suffolk, and Targhee) and western white-faced commercial ewes and to determine whether the R allele is associated with ewe and lamb production traits. Genotyping was performed on 532 ewes and 901 lambs from the University of Wyoming flock, in addition to 820 rams from 52 sheep producers from Wyoming and surrounding areas, using a DNA mismatch assay that discriminated the R allele from others at codon 171. Genotyping was performed by DNA sequencing on 127 rams representing all breeds, except Hampshire from the USDA Sheep Experiment Station at Dubois, ID. The 171R allele was found in all five breeds and in the commercial western white-faced ewes. Genotype frequencies varied (P < 0.001) by breed in ewe and ram populations. Influence of R-allele frequency on ewe lambing records and individual lamb records was analyzed for Columbia (62, 161, 121), Hampshire (89, 193, 162), Rambouillet (87, 179, 133), Suffolk (67, 178, 161), and commercial sheep (227, 463, 324) for numbers of ewes, total number of ewe production records, and individual lamb records, respectively. Suffolk ewes without the R allele (non-R/non-R) gave birth to more (P or= 0.08) by ewe genotype. Lamb birth and weaning weights were not influenced (P >or= 0.12) by lamb genotype in any of the breeds or in the commercial flock. In this population, ultimate lamb production was only influenced by genotype at codon 171 in the Suffolk flock.  相似文献   

4.
The 4 yr productivity of 25% (QF; n = 533) and 50% (HF; n = 531) Finnsheep ewes exposed to either Suffolk or Columbia rams in one of three production systems was monitored to test the effects of system, terminal sire breed, maternal line, and their interactions on annual market lamb production. Ewe lambs and yearlings were randomly assigned to either a high-input accelerated lambing system (HIGH), a high-input annual system (MED), or a low-input annual system (LOW). Nursery facilities were available for weak lambs or those born in triplet or more births for the HIGH and MED but not for the LOW systems. Accelerated lambing protocol required early weaning. Sex-adjusted lamb weaning weights were corrected to within-system mean ages of 42 d for HIGH and 70 d for MED and LOW. The HIGH ewes weaned 1.55 lambs per year compared with 1.46 for MED and 1.18 for LOW (P less than .01). However, because of early weaning, HIGH yielded the lowest weight of weaned lamb per year. The MED ewes weaned 5.9 and 11.1 more kilograms of lamb per year than the LOW and HIGH ewes, respectively (P less than .01). The HIGH system may be economically feasible if young lambs could be inexpensively grown to feeder or market lamb weight. The HIGH ewes did not, however, increase lamb numbers in proportion to increased exposures compared with the annual systems. Breed-group effects for ewe productivity (kilogram of lamb weaned per ewe per year) were consistent across management systems, although some interactions among breed group and system were present for components of productivity. Suffolk rams yielded an advantage of 1.6 kg of weaned lamb per exposure over Columbia rams (P less than .05) due to a 3% better lamb survival (P less than .01) and heavier weaning weight, especially in the LOW system. The HF ewes weaned .1 more lambs per exposure than QF ewes (P less than .01); .06 of the lambs were nursery-reared. However, lambs from HF ewes had a 2% lower survival rate (P less than .05) and were 1.4 kg lighter at weaning (P less than .01), so overall productivity among HF and QF ewes was similar.  相似文献   

5.
Ewe performance was compared for five pure breeds of sheep (Finnsheep, F; Rambouillet, R; Dorset, D; Targhee, T; Suffolk, S) and the crosses in development of two maternal composite lines (C1 = 1/2F1/4R1/4D and C2 = 1/2F1/4T1/4S). The data involved 10,959 breeding season records of 4,219 ewes by 412 sires. Ewe production and the components (fertility, litter size, neonatal and preweaning lamb survival and mean lamb weaning weight) were adjusted for age and standardized across season of lambing and years. The D and F ewes produced more weight of lamb/ewe exposed than R, S and T ewes because of higher D and F fertility, higher D lamb survival and larger F litters. First cross and inter se generations of C1 and C2 ewes averaged 17 to 27% higher fertility than the parental mean. Litter size averaged about one lamb higher for F than for other pure breeds, but only slightly higher for C1 and C2 than for the mean of F and other breeds. Lower neonatal survival for F than for other breeds and crosses was associated with the larger F litters and with 2 to 8% positive heterosis in the crosses. Preweaning survival of suckled and nursery lambs was low for F and S and positive heterosis ranged from 9 to 19% in crosses. Mean lamb weaning weights were highest for S, lowest for F, with little heterosis in crosses. Crossbred ewes reared .3 to .4 more lambs than mean for parental pure breeds. Heterosis in C1 and C2 ranged from 11 to 28% for lambs born, 27 to 43% for lambs weaned and 29 to 44% for weight of lamb weaned/ewe exposed. Decline in heterosis with inter se mating of crosses was no greater than expected from the reduction in predicted heterozygosity.  相似文献   

6.
Breeding ewes to lamb at 1 yr of age can improve profitability for some production systems. The first objective of this study was to evaluate the effect of age and weight at breeding and total postweaning weight gain on reproductive performance of ewe lambs. The second objective was to compare the effects of weight and age variables in four major sheep breeds (Columbia, Polypay, Rambouillet, and Targhee). Weights, ages, and the binary traits of fertility (pregnant or nonpregnant) and prolificacy (one lamb born vs. two or more) were collected on 2,055 ewe lambs at the U.S. Sheep Experiment Station, Dubois, ID, from 1984 through 1988. The effects of age and weight at breeding and total weight gain from weaning to breeding on fertility and prolificacy were analyzed with a logit model in a maximum likelihood analyses. Differences (P < 0.001) among breeds for fertility were identified, with a 93% fertility rate for Polypay ewe lambs compared with lower fertility rates in Columbia, Targhee, and Rambouillet ewe lambs (50, 60, and 75%, respectively). The percentage of multiple births (prolificacy rate) also was higher (P < 0.001) in the Polypay (47%) than in Columbia, Targhee, and Rambouillet breeds (1, 13, and 14%, respectively). Averaged across breeds, weight at breeding had a positive effect on fertility and prolificacy (P < 0.001), whereas total weight gain from weaning to breeding had a positive effect only on fertility (P < 0.027). In separate analyses for each breed, increasing age (P < 0.001) and weight at breeding (P < 0.001) increased the probability of pregnancy in Rambouillet ewe lambs. The probability of pregnancy for Targhee ewe lambs increased (P < 0.005) with weight at breeding. Increasing weight at breeding increased (P < 0.004) the probability of multiple births in all breeds. Increasing total postweaning weight gain increased (P < 0.007) the probabilities of multiple births in Rambouillet and Targhee ewe lambs. In conclusion, Polypay ewe lambs were superior in fertility and prolificacy to Columbia, Rambouillet, and Targhee under Western range conditions. Improved reproductive performance of Columbia, Rambouillet, and Targhee ewe lambs may be achieved by increasing age and weight at breeding and postweaning gain.  相似文献   

7.
A total of 64 Rambouillet ewes was utilized in this study. Ewes were fed a 50:50 mixture of alfalfa and prairie hay ad libitum and either no concentrates (C), .4 kg concentrates . head-1 X d-1 (S) or .4 kg concentrates containing 73 ppm lasalocid . head-1 X d-1 (SL) during the last 50 d of pregnancy and through 60 d of lactation. A total of 163 skin samples was obtained from the mid-side region of the lambs at birth, 1 and 2 mo of age, and follicle traits were estimated by histological techniques. Wool growth per unit area (100 cm2) was estimated by clipping wool from both right and left mid-sides of all ewes 60 d postpartum. Birth weight of single lambs did not differ (P greater than .20) among treatments. Twin lambs of supplemented ewes were heavier (P less than .01) at birth than those of control ewes and the difference between S and SL groups was not significant. Compared with the control, concentrate supplementation with or without lasalocid increased (P less than .01) postnatal lamb survival and ewe productivity, expressed as kilograms of lamb weaned per ewe lambed. The C, S and SL groups weaned 12.50, 18.52 and 20.72 kg/ewe lambed (P less than .01), respectively. Maternal concentrate supplementation did not influence secondary to primary wool follicle ratio (Sf/Pf) of single lambs (P greater than .20). Twin lambs of the S ewes tended to have higher Sf/Pf than controls. The SL twins had intermediate Sf/Pf values (P greater than .20).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

8.
Six ewe genotypes, generated by mating Coopworth (C), Polypay (P), and Suffolk (S) rams to P and Coopworth-type (Ct) ewes, were exposed to Hampshire rams for spring lambing from 1987 through 1990. Data from 1,013 exposures and 973 resultant lambings were used to analyze reproductive traits and cumulative ewe productivity over 4 yr. Ewe body and fleece weights were also analyzed. Ewes from S sires weaned the heaviest lambs and ewes from P sires weaned the largest number of lambs, resulting in similar total weight of lamb weaned per ewe mated. Coopworth-sired ewes weaned the least total weight of lamb per ewe mated. Ewes weaning twins produced 54% more total litter weight per ewe than those weaning singles. Annual ewe survival averaged 95%, ranging from 93% for S x P and C x P ewes to 97% for P x Ct and C x Ct ewes. When cumulative number and weight of lamb produced was assessed on the basis of all ewes starting the trial, P-sired ewes were highest, followed in order by daughters of S and C sires. Suffolk-sired ewes (67 kg) were 13% heavier than daughters of P rams and 19% heavier than daughters of C rams. Adjustment of lamb production for ewe metabolic body size resulted in C-sired ewes being more efficient than the heavier S-sired ewes. Coopworth-sired ewes produced 32% more wool than ewes sired by the other two breeds. Differences in wool production between ewes weaning one or two lambs were small.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

9.
Forty-eight Blackbelly X Dorset, 27 Finnish, 26 Finnish X Dorset, 28 Rambouillet and 8 Dorset Suffolk-sired lambs were used in this experiment. Three weeks before lambing, one-half of the ewes received a selenium emulsion (Se-E) containing .05 mg selenium and 3.7 IU of vitamin E/kg body weight (BW). A 2 X 3 X 2 factorial arrangement was used; lambs from either treated or nontreated ewes were randomly assigned irrespective of breed to one of six treatment combinations consisting of 0 or .025 mg/kg BW selenium (Se) injected at birth or two .025 mg/kg BW Se injections, one at birth and one 2 to 3 wk later, and two levels of injectable Vitamin E (E; 0 and 100 IU) given at birth. Both lambs and ewes were provided access to 75% concentrate diets supplemented with Se and E at recommended NRC levels. Plasma activity of creatine phosphokinase (CPK) was highest at 1 d of age and exhibited decreases (P less than .001) over time. In lambs, the E injection tended to decrease plasma activity of CPK. Plasma glutathione peroxidase activity was lowest at 1 d of age and increased over the course of the experiment but was unaffected by treatments (P less than .05). Plasma tocopherol concentration decreased (P less than .01) with time, with E therapy tending to increase tocopherol concentration. Differences in mean plasma tocopherol concentrations among breeds were also observed (P less than .01). Selenium concentration increased over time and with the E injection (P less than .01). An interaction between ewe and lamb Se-E treatments also was observed (P less than .10), with nontreated lambs from nontreated ewes exhibiting lower Se concentrations than treated lambs from injected ewes. An increase in lamb plasma Se concentration was noted in response to Se-E treatments (P less than .001). In the ewes, plasma tocopherol concentration was lower while Se concentration was higher at 18 d than at 1 d postpartum (P less than .01 and P less than .001, respectively). Milk Se concentration was lower at 18 d than at 1 d (P less than .001) and was higher (P less than .10) in Se-E-treated ewes.  相似文献   

10.
Multiparous Suffolk and Suffolk-cross ewes were randomly allotted to treatments within breed and year to measure effects of ram exposure, during transition from anestrus to breeding activity, on reproductive performance. Treatments were: 1) ewes joined with two mature vasectomized Rambouillet rams for 15 d before breeding (DC), 2) ewes maintained across a net wire fence from two vasectomized rams for 15 d before breeding (FC) and 3) ewes maintained approximately 400 m away from rams (NC). At the end of the 15 d, all ewes were placed in one pasture and mated to three fertile Suffolk rams during a 34-d breeding season. A total of 96 Suffolk and 177 Suffolk-cross ewes was utilized during the 3-yr experiment. A greater (P less than .05) prebreeding ovulation percentage was observed in DC and FC than in NC ewes. Mating and lambing occurred approximately 6 d earlier for DC or FC ewes than for NC ewes. A similarly designed experiment was conducted using Suffolk and Suffolk-cross ewe lambs allotted to treatments within breed and year to measure effects of ram exposure during the natural breeding season, but prior to breeding. Treatment differences were not detected (P greater than .05) for date of first observed estrus, date of lambing, percentage of ewes lambing in the first 17 d of the lambing season, number of lambs born per ewe lamb exposed or number of lambs born per ewe lamb giving birth.  相似文献   

11.
Suffolk x Rambouillet ewes were used in two consecutive years to test the ability of Dorset and Suffolk yearling rams to stimulate ovulation and estrus in early summer (late June and July) breeding. After spring weaning about June 1, ewes were randomly divided into three groups and for 2 wk either were isolated from rams or were preexposed to either yearling Dorset or Suffolk rams by penning of rams in proximity to ewes. Ewes then were rerandomized into two groups for joining with either yearling Dorset or Suffolk rams fitted with marking harnesses. Serum progesterone profiles and crayon marks were used as indicators of ovulation and estrus. Overall lambing rate was not different among preexposure treatments for the 2 yr. However, early lambing rate (in the first 14 d of lambing season) was significantly affected by preexposure group (24% for Dorset vs 9% for Suffolk and 10% for isolation), especially in the 2nd yr (31% for Dorset vs 8% for both Suffolk and isolation). Ewes preexposed to Dorsets also lambed 10 d earlier (P less than .05) than ewes preexposed to Suffolks in yr 2, but the groups did not differ in yr 1. Ewes exposed to Dorset rams for breeding had higher overall lambing rates than ewes bred to Suffolks (75% vs 54%), especially in the 1st yr (77% vs 48%). Lambs sired by Dorset rams were born 6 d earlier in yr 1 (P less than .05) but only 1 d earlier in yr 2. Data from both years indicate that Dorsets are superior to Suffolks in ability to sire lambs in fall lambing systems.  相似文献   

12.
Data from 644 exposures and 552 lambings were used to analyze reproductive traits of 1/2-Finnish Landrace, 1/2-Dorset ewes (1/2 Finn); 1/4-Finnish Landrace, 3/4-Dorset ewes, (1/4 Finn) and Dorset ewes. Ewes were exposed to Hampshire or Suffolk rams for spring lambing from 1973 to 1978. The analytical model included fixed effects of ewe birth year (EBY), ewe breed (BR), lambing year within EBY and EBY X BR interaction and random effects of ewe within EBY and BR. Conception rate differed (P less than .01) for 1/2-Finn (.94), 1/4-Finn (.88) and Dorset (.80) ewes. Litter size was highest (P less than .01) for 1/2-Finns (1.97), followed by 1/4-Finns (1.74) and Dorsets (1.44). The 1/2-Finn ewes ranked first for number and weight of lambs weaned, and for number and weight marketed as feeder lambs. Birth weights were heavier (P less than .001) for lambs with Dorset dams (3.88 kg) than for lambs with 1/4-Finn (3.24 kg) or 1/2-Finn (3.08 kg) dams. Preweaning average daily gains and adjusted 90-d weights were also larger (P less than .001) for lambs with Dorset dams (.26 kg/d and 28.3 kg, respectively) than for lambs with 1/4-Finn (.24 kg/d and 25.4 kg) or 1/2-Finn (.24 kg/d and 25.1 kg) dams. However, Dorset ewes lambed an average of 10.5 d later than Finn-cross ewes, and actual weaning weights (unadjusted for age) did not differ significantly among lambs from Dorset (27.2 kg), 1/4-Finn (26.9 kg) and 1/2-Finn ewes (26.7 kg).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

13.
Six ewe genotypes, generated by mating Coopworth (C), Polypay (P), and Suffolk (S) rams to Polypay and Coopworth-type (Ct) ewes, were exposed to Hampshire rams for spring lambing from 1986 through 1990. Data from 1,092 exposures and 1,044 resultant lambings were used to analyze reproductive traits and lamb growth rates. Overall conception rate averaged 95% and ranged from 93% for S x Ct ewes to 97% for P x Ct ewes. Mean litter size at birth averaged 1.63 and ranged from 1.45 for C x C ewes to 1.75 for S x P ewes. Ewes from P dams had higher mean litter size (P less than .01) than those from Ct dams (1.73 vs 1.54), but differences between sire breeds were not significant. Incidence of lambing assistance was similar for ewes producing single or multiple lambs. Lamb birth weight influenced the level of assistance rendered to single-bearing but not to multiple-bearing ewes. Lambing assistance was not related to lamb survival, probably because the high surveillance level minimized trauma before assistance was rendered. Incidence of required assistance declined over subsequent parities. Lamb birth weights were affected by ewe genotype and increased with increasing ewe age. Survival of single-born lambs averaged 94% and was not affected by dam genotype. Survival of twins averaged 85%, ranging from 79% for lambs from S x Ct ewes to 89% for lambs from P x P ewes. Suffolk-sired ewes produced the heaviest mean birth and weaning weights for both singles and twins. Coopworth-sired ewes weaned heavier single lambs but lighter twins than P-sired ewes.  相似文献   

14.
Range ewes are commonly evaluated for milking ability by producers to determine the ewe's ability to rear lamb(s). The U.S. Sheep Experiment Station has subjectively scored (low, average, high) a ewe's milking ability within 24 h of lambing for many years. The relationship of subjective milk scores with lamb production was investigated using lambing records of Columbia (n = 1,731), Polypay (n = 1,129), Rambouillet (n = 1,704), and Targhee (n = 1,638) ewes. The incidence of high milk scores increased from less than 10% at first parity to 29 to 40% at second and greater parities. At maturity, Columbia ewes (38%) had the highest percentage of high milk scores. A positive association existed between ewe BW and her milk score at third and later parities. Ewes with high milk scores gave birth to heavier lambs (P < 0.05), whereas ewes with low milk scores were associated with lighter (P < 0.05) lambs at birth. Ewes with low milk scores weaned less (P < 0.05) total weight than ewes with better milk scores across all age groups for all breeds. Lighter weaned litter weights from ewes with low milk scores were linked to lighter birth weights and fewer weaned lambs. Differences for litter weight weaned between ewes with average and high milk scores were generally observed at 2 and 3 yr of age, when litter weights were heavier among ewes with high milk scores (P < 0.05) for all breeds. Between the ages of 1 and 3 yr, Columbia, Polypay, Rambouillet, and Targhee ewes with an average milk score weaned heavier (P < 0.05) litters (average differences of 10, 9, 13, and 12%, respectively) than ewes with low milk scores. For all breeds at all ages, individual lamb weaning weights were heavier (P < 0.05) when they were reared by ewes with high milk scores compared to lambs reared by ewes with low milk scores. Results suggest that milk score is an economically important trait in these four breeds and should be considered in management and breeding objectives; at a minimum, the incidence of low milk scores should be kept as small as possible.  相似文献   

15.
Two groups of 24 Hampshire and 26 Suffolk purebred ewes each were used to study effects of cohabitation with cyclic white-faced (WF) ewes on estrous activity in June. Ewes lambed in January, February and March and had been isolated from mature rams since the previous fall breeding. From June 1 to July 2, treated (T) ewes were exposed to vasectomized rams and to 65 WF ewes; control (C) ewes were exposed only to vasectomized rams. Ovulation was assessed with biweekly serum progesterone assays; crayon marks were used to detect estrus. Daily observations of ram behavior were conducted to assess sexual activity of rams joined with T and C ewes. Cohabitation with WF ewes increased (P less than .01) ovulation percentages from 46% in C (42% for Hampshires and 50% for Suffolks) to 76% in T ewes (79% for Hampshires and 73% for Suffolks). Mating percentage also was increased (P less than .05) by cohabitation with WF ewes from 14% for C ewes to 30% for T ewes. Rams with T + WF ewes spent more (P less than .05) time checking ewes for estrus than did rams with C ewes. Hence, cohabitation with cycling WF ewes increased ovulation and mating percentages. Many acyclic T ewes first ovulated after 10 or more days of teasing, possibly due to increased ram contact in the presence of WF ewes.  相似文献   

16.
The prevalence of infection with ovine progressive pneumonia (OPP) virus and its effects on ewe wool and lamb production were investigated in a flock of 2,976 ewes of 6 breed types (Rambouillet, Targhee, Columbia, Polypay, 1/4 cross Finnsheep, and 1/2 cross Finnsheep). Prevalence of seropositivity was significantly (P less than or equal to 0.01) lower among Rambouillet and Targhee breeds (44 and 42%, respectively), intermediate in Polypay, Columbia, and 1/4 cross Finnsheep (approximately 53%), and higher among 1/2 cross Finnsheep (62%). Seropositivity increased with age in all breed types from 11% at 1 year of age to 93% at greater than or equal to 7 years of age. Lateral disease transmission is indicated by linear increase of seropositivity prevalence with increasing age, including that in sheep greater than 6 years old. Subclinical infection with OPP virus had no apparent detrimental effect on number of lambs born, lamb viability, birth weight, number of lambs weaned, or growth rate of single and twin lambs, compared with findings for noninfected sheep in the same flock. Mature ewe body weight and grease fleece weight did not differ between subclinically infected seropositive and seronegative ewes. Subclinical infection with OPP virus does not appear to have an adverse economic effect on ewe wool and lamb production. Culling rate attributable to clinical manifestation of infection with OPP virus must be accurately determined before the true effects of virus infection on production can be determined and an eradication program can be recommended.  相似文献   

17.
Two experiments were conducted to examine the milk producing ability of Western White-Faced sheep and to identify traits that correlate well with milk production. In Exp. 1, 31 Targhee ewes were milked and five samples were taken during 107-d lactations in which the ewes nursed twin lambs. Milk yield and composition, lamb weights, ewe weights, wool growth, and udder size also were measured. In Exp. 2, 24 ewes (Rambouillet x Finn-Dorset) were separated from their lambs at 7 wk and milked twice per day for eight more weeks, during which milk yield and composition, feed consumption, udder width, and ewe weights were measured. Results from Exp. 1 showed that lamb 30-d weights, ewe weights at breeding time, and udder width at peak lactation were highly correlated with suckled milk yield (r = .81, .75 and .66, respectively). Results from Exp. 2 indicated that lamb weights and ewe weights were not useful for predicting milk yield in dairy ewes, but feed intake and udder width were (r = .74 and .86, respectively). Single-day milk yield measurements were excellent estimators of total lactation yield in both experiments. Milk yields averaged 1,714 g/d in the suckled ewes and 477 g/d in the dairy ewes.  相似文献   

18.
Targhee sheep were selected for 120-d weight under irrigated pasture-drylot conditions at Davis (DW) and under range conditions at Hopland (HW). Unselected control lines were maintained in both environments (DC, HC1 and HC2). At Hopland, a line (DH) was maintained in which ewes were mated to Davis (DW) rams. Selection for 120-d weight was successful in both environments, with more improvement made in the drylot environment. The genetic improvement made in the drylot environment was expressed, although to a lesser degree, under range conditions. Correlated responses were analyzed. Birth weight increased significantly in all three selected lines; the increase was less in line DH than in the other two lines. In all selected lines, weights of ewes of all ages at mating increased significantly compared with their respective controls. Proportion of ewes lambing decreased (P less than .05) in line DH; the trend was negative but nonsignificant in line DW. Differences in litter size between lines within location were not significant. Lamb survival to weaning decreased in lines DW (P less than .05) and DH (P less than .01), compared with their respective controls; and the trend in HW was negative but nonsignificant. Fertility and survival data indicated that, under range conditions, the line selected under drylot conditions (DH) was less fit than the line selected under range conditions (HW). As a result of the decreases in lamb survival and fertility, none of the selected lines produced more total lamb weight weaned per ewe than the controls, in spite of the significant direct response to selection. Mature ewes of lines DH and DW produced less total lamb weight weaned per ewe (P less than .001 and P less than .05) than their respective controls. The results indicate that while single trait selection for growth rate to weaning results in heavier lambs, it does not increase and may decrease total lamb production per ewe.  相似文献   

19.
A group of crossbred Dorset or Finnish Landrace ewes maintained under a synthetic light regimen (Light Treatment, 4 mo long days - 16 h light, 4 mo short days - 8 h light) and exposed to rams every 8 mo (January 1, September 1, May 1) was compared for lamb production over a period of 4.5 yr with two other comparable groups under natural daylight conditions, one exposed to rams once a year in the fall (Control I) and the other every 8 mo (Control II). Conception rates across breed type of ewe were 92% for Control I, 66% for Control II and 83% for Light Treatment ewes. Conception rates for May breedings only were 16% in Control II and 88% in Light Treatment ewes. Prolificacies of crossbred Finn ewes were higher (P less than .05) than those in crossbred Dorset ewes of Control I (258 vs 193%), Control II (187 vs 165%) and Light Treatment (238 vs 163%). The annual production at lambing from the crossbred Finn and Dorset ewes in Control I was 251 and 206 lambs/100 ewes exposed to rams, respectively. Corresponding productions were 231 and 178 for Control II and 296 and 211 for Light Treatment ewes. Mortality of lambs from the crossbred Finn ewes (27%) was higher (P less than .01) than that from the crossbred Dorset ewes (12%). Annual attrition of the crossbred Dorset ewes in Control I, Control II and Light Treatment groups was 5.2, 5.4 and 5.4%, respectively. Corresponding percentages of the crossbred Finn ewes were 7.0, 8.8 and 11.2.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

20.
Data on ewe body weights and on lamb birth and weaning weights and survival rates were recorded on a total of 557 multiparous Rambouillet, Hampshire X Suffolk and Synthetic I (composite of Finnish Landrace, Rambouillet and Polled Dorset) ewes in two experiments started after the first trimester of gestation. In Exp. 1, a 2 X 2 factorial arrangement of treatments included all combinations of low (.24% in gestation and .48% in lactation), or high (.80%) dietary Ca and low (20 ppm) or high (74 ppm) dietary Zn. No effect of dietary Ca or Zn level and no Ca X Zn interaction with respect to number of lambs born or weaned, birth weight, weaning weight or survival rate of the lambs or body weight of the ewes was shown. Mean number of lambs born was 1.63 +/- .71 with a survival rate of 85.0 +/- .3% and a weaning weight (59 d) of 19.4 +/- 4.4 kg. Experiment 2 was a repeat of Exp. 1 except that two intramuscular injections of vitamins A, D and E (d 65 and 93 of experiment) were given to one-half of the ewes in each diet group. There was no effect of dietary Ca or Zn level or of vitamin administration on ewe body weight changes, number of lambs born (1.89 +/- .55), survival rate (86.6 +/- .3%), lamb birth weight 4.6 +/- 1.5 kg) or lamb weaning weight (23.2 +/- 7.2 kg). Blood plasma Ca, inorganic P and Mg concentrations of ewes in late pregnancy were unaffected by diet or vitamin injections.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

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