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1.
Data were obtained from a population consisting of 160 Merino ewes, as well as 64 male and 75 female progeny of these ewes at the 2-tooth age. The age and sex groups were maintained in separate flocks. The population has been divergently selected from the same base since 1986, either for (high or H line) or against (low or L line) maternal multiple rearing ability. All animals were inspected for sheep lice (Bovicola ovis) during September/October 2002 after a wool growth period of at least 4 months. When expressed relative to mean L-line performance, the advantage in lambs weaned per ewe during the lambing season amounted to approximately 110% in the H line (1.01 vs 0.48; P < 0.01). The proportion of animals on which 1 or more lice were observed were markedly lower in 2-tooth replacement ewes than in replacement rams and mature breeding ewes (0.053 vs 0.625 and 0.531, respectively; P < 0.01). One or more lice were observed on a lower proportion of H-line ewes than on those of the L line (0.413 vs 0.571, respectively; P < 0.10), while a similar tendency was observed in 2-tooth ewe hoggets (0.033 vs 0.143, respectively; P = 0.16). When the mean number of lice on individuals on which 1 or more lice were observed was compared between lines, the average number of lice observed on H-line young rams was lower than in the L line (4.36 +/- 0.85 vs 9.71 +/- 1.84 lice, respectively; P < 0.01). A similar tendency was observed in mature breeding ewes (2.15 +/- 0.38 vs 3.22 +/- 0.42 lice, respectively; P < 0.20). The more highly reproductive H-line ewes were not more susceptible to infestation with B. ovis than ewes of the L line. In fact, available evidence suggest that H-line animals could be more tolerant of B. ovis than those of the L line.  相似文献   

2.
Two experiments were conducted with Polypay ewes nursing twin lambs to evaluate the effects of supplementing fat (calcium salts of palm oil fatty acids or hydrogenated tallow) on ewe lactation. In Exp. 1, ewes were fed a 52% concentrate:48% hay-based diet (as-fed basis) consisting of alfalfa hay (n = 4), endophyte-free fescue hay (n = 4), or fescue hay with 3.7% fatty acids (n = 4) from d 4 to 56 of lactation. In Exp. 2, ewes were fed similar diets that had endophyte-free fescue hay (n = 6), fescue hay with 3.7% fatty acids (n = 5), or fescue hay with 3.1% tallow (n = 6) from d 14 before lambing until d 57 of lactation. Diet formulations with supplemental fat were more nutrient dense, and treatments were fed to meet ewe nutrient requirements; this caused diets with added fat to be offered at 10 and 17% lower rates than unsupplemented diets in Exp. 1 and 2, respectively. Lambs were maintained to consume only ewe milk. Ewe milk production and composition were determined using a portable milking machine following a 3-h separation from lambs. In Exp. 1, milk fat content was increased (P < 0.01) when ewes consumed fescue hay with fatty acids vs. the fescue hay diet (11.4 vs. 8.3%). Ewes fed fescue hay with fatty acids lost the most (P < 0.05) weight over lactation (-8.6 kg) compared with ewes fed the alfalfa hay (-2.4 kg) and fescue hay (-3.8 kg) diets. Other milk measures, lamb gain, and production efficiencies were not changed. In Exp. 2, ewes supplemented with fatty acids produced more (P < 0.05) milk fat than those fed tallow (290 vs. 210 g/d). The proportion of synthesized milk fat 14:0 was decreased (P < 0.01), but the percentage of incorporated 16:0 increased (P < 0.05) when fatty acids were fed. Dietary fat digestibility by ewes was increased (P < 0.01) by fatty acid supplementation but decreased (P < 0.01) when tallow was added. Although ewe weight measures were not changed in Exp. 2, twin lamb gain per ewe organic matter intake was most efficient (P < 0.05) when ewes were supplemented with fatty acids. Results suggest that feeding hydrogenated tallow decreased nutrient availability for ewe milk fat production. A complete diet based on endophyte-free fescue hay can replace a traditional alfalfa hay diet, whereas supplementing with the calcium salts of palm oil fatty acids may be more feasible when energy is limiting during ewe lactation.  相似文献   

3.
Fifty-two Targhee twin-bearing ewes were used in a factorial arrangement of treatments to investigate the role of supplemental vitamin E (vit E); 0 (NE) vs 400 IU of vit E x ewe x (-1)d(-1) (E) and parainfluenza type 3 (PI3) vaccination; none (NP) vs PI3 vaccination (P) in immune function. Parainfluenza type 3 vaccination was used to evoke an immune response. Ewes receiving PI3 were vaccinated at 49 and 21 d before the expected lambing date. Ewes receiving vit E were orally dosed daily, 32 to 0 d before lambing. Blood was collected from ewes at the time of the initial PI3 vaccination and 4 h postpartum. Blood was collected from lambs (n = 104) at 3 d postpartum. Ewe and lamb sera were analyzed for anti-PI3 antibody titers, immunoglobulin G (IgG) titers, and vit E concentrations. Colostrum was collected 4 h postpartum and analyzed for IgG. The model for ewe and lamb analysis included the main effects of vit E and PI3, sex (lambs model only), and their interactions. No interactions were detected (P > 0.20) for any ewe or lamb variables. Serum anti-PI3 titers were greater (P < 0.01) in P ewes and their lambs than NP ewes and their lambs. Serum vit E concentrations were greater (P < 0.01) in E ewes and their lambs than NE ewes and their lambs. Colostral IgG titers and serum anti-PI3 titers did not differ (P > 0.20) between E and NE ewes. Serum IgG titers in E ewes and their lambs did not differ (P > 0.15) from IgG titers in NE ewes and their lambs. Lamb anti-PI3 titers did not differ (P = 0.76) between lambs reared by E and NE ewes. These results indicate that, although supplemental vit E to the ewe increased lamb serum vit E concentration, it had no effect on measures used in this study to assess humoral immunity in the ewe or passive immunity to the lamb.  相似文献   

4.
The experiment involved 40 mid-lactating Comisana ewes. The animals were housed in straw-bedded pens and assigned to a control group (n = 10) and two test groups of 15 subjects each. Control ewes were never moved from their pen and peers throughout the experiment period, whereas test animals were subjected to either regrouping (RG) or regrouping and relocation (RGRL) three times at weekly intervals (d 7, 14, and 21 of the trial). Three behavioral recordings were conducted after each social and pen exchange over a 6-h period (1000 to 1600). Animals from groups RG and RGRL were bled immediately before each regrouping and relocation and 15 and 60 min afterward. The phytohemagglutinin skin test was performed at d 9, 16, and 23. Milk yield was recorded when the ewes were mixed and moved, and before and after each mixing and moving procedure. Individual milk samples were analyzed for composition, renneting parameters, and bacteriological characteristics; samples with more than 10(6) somatic cells/mL were cultured for mastitis-related pathogens. Control ewes spent more time lying than groups RG (P < 0.001) and RGRL (P < 0.01) and less time in ambulatory activities than RGRL sheep (P < 0.05). Moved and remaining ewes showed a higher number of aggressive interactions than control subjects (P < 0.001 and P < 0.01, respectively). Control sheep showed the highest cell-mediated immune response compared with both moved and mixed ewes (P < 0.001 and P < 0.01, respectively). The RGRL ewes gave lower yields of milk than did the control ewes on the days after the first (P < 0.05) and the second (P < 0.01) change of pen and peers. The RGRL ewes also had a lower fat content (P < 0.05) than control ewes in the milk yielded on the day of the first regrouping and relocation and a lower milk protein content (P < 0.05) on the following day. The RG treatment resulted in the ewes yielding milk with a lower fat content (P < 0.01) on the day of each mixing procedure as compared with controls and in a decreased milk protein content on the days after the first (P < 0.05) and the second regrouping (P < 0.01). One case of subclinical mastitis was recorded in both the RG and RGRL groups, whereas no cases were detected in control group. These findings suggest that regrouping and relocation may cause increased aggression, altered immune responses, and short-term effects on the production performance of lactating ewes. These practices should be performed by attempting to minimize their impact on animal welfare.  相似文献   

5.
Performance of the Dorper and Mutton Merino breeds and their crosses was assessed from 1,305 ewe and 1,453 lamb records from six lambing seasons. Dorper and Mutton Merino were mated in all combinations under an accelerated lambing system and crossbred females were mated to Suffolk rams. The Dorper and Mutton Merino breeds were not significantly different for fertility, pre-weaning lamb growth and survival. Suffolk sired lambs from crossbred ewes grew rapidly and were heaviest at birth and at weaning. They also survived better than lambs from the other breeding groups and this contributed to the higher weaning rate (P less than 0.05) in crossbred ewes. Weight of weaned lambs per ewe exposed to the ram per season was 12% higher (P less than 0.05) in the Dorper than the Mutton Merino ewes. However lifetime production was 28% higher (P less than 0.01) in Mutton Merino ewes due to significantly superior longevity. Crossbred ewes were highly productive. Individual heterosis was not significant but estimates were positive for most traits. Growth rate and survival of lambs increased as age of dam increased to 48 and 40 months respectively. Lambs born to previously non-lactating ewes were heavier and survived better than lambs born to ewes lactating in the previous season. Lambs born and reared as singles were 25% heavier at birth (P less than 0.001) and 52% heavier at weaning (P less than 0.001) than those born and reared as twins. Male lambs grew faster and were 7% heavier at weaning than females (P less than 0.001).  相似文献   

6.
Yearling Targhee ewes (n = 24; not pregnant or lactating) were used in a 2 x 2 factorial arrangement of treatments to determine the effects of supplemental vitamin E (0 IU [0vitE] vs 330 IU vitamin E x ewe(-1) x d(-1) [+vitE]) and Zn (0 mg [0Zn] vs 140 mg Zn x ewe(-1) x d(-1) [+Zn]) on serum alpha-tocopherol concentrations, antibodies to parainfluenza type 3 (PI3), ewe BW, Zn liver concentrations, and serum alkaline phosphatase activity. Ewes were managed as one group, grazed native pasture, and had ad libitum access to white salt and water. Ewes that received supplemental vitamin E were orally dosed every other day with 660 IU of DL-alpha-tocopherol acetate in a gelatin capsule beginning on d 1 and continuing to d 63 of the study. Ewes that received Zn supplement were orally dosed every other day with 280 mg of Availa-Zn 100 (Zinpro Corp., Eden Prairie, MN, IFN 6-32-054) in gelatin capsules for 63 d. All ewes were vaccinated with killed PI3 on d 22 and 42. No interactions were detected (P > 0.35); however, serum alpha-tocopherol concentrations and PI3 antibody titer dilutions changed (P = 0.001) over the length of the study. Ewe BW change, serum alkaline phosphatase activity, and liver Zn concentrations did not differ (P > 0.22) between 0Zn and +Zn or 0vitE and +vitE ewes. Serum a-tocopherol tended to be higher (P = 0.08) in +vitE than 0vitE ewes and was numerically higher (P = 0.16) in +Zn than 0Zn ewes. Antibody titer dilutions were higher (P = 0.06) in 0Zn than +Zn ewes and did not differ (P = 0.83) between 0vitE and +vitE ewes. These results indicate that high levels of supplemental Zn may have a tendency to improve serum alpha-tocopherol concentrations but may have negative impacts on humoral immune function.  相似文献   

7.

Sheep feeding regimes were studied in years when little roughage was available by comparing two levels of concentrate (high and low) and three types of roughage [silage, hay and ammonia-treated (AT) straw]. The duration of the experiment was two production years (1995 and 1996) and included 121 ewes. The traits recorded were live weight for ewes, ewe performance (number of lambs, birth weight, average daily weight gain) and slaughter data (class, value and weight). After 14 weeks, ewes fed low-concentrate AT straw were 6-12 kg lighter ( P < 0.01) than the other ewes, and tended to be undernourished. Lambs from these ewes were up to 1.5 kg lighter at birth ( P <0.01) than the other lambs. No difference was found at the end of the experiment. The gross margin in the group fed the high-concentrate AT straw diet was 205 NOK higher ( P <0.01) than the group with the lowest gross margin (low-concentrate hay). Wool and wood eating was found in groups fed large amounts of concentrate and silage.  相似文献   

8.
The objective of this study was to describe the responses of the plasma progesterone and cortisol concentrations in ovariectomized lactating cows to low doses of adrenocorticotropic hormone (ACTH). The estrous cycles in 3 lactating cows were synchronized, and the cows were ovariectomized in the luteal phase. ACTH challenge tests were conducted at doses of 3, 6, 12 and 25 IU. Blood samples were collected at 30 min intervals, and the plasma progesterone and cortisol concentrations were analyzed by EIA. A concomitant rise in plasma progesterone and plasma cortisol was observed in cows treated with 12 IU or higher doses of ACTH. Significant increments in the plasma cortisol concentrations were observed at all doses of ACTH. The means (+/- SE) of the peak plasma progesterone concentrations after the 3, 6, 12 and 25 IU ACTH challenge tests were 0.6 +/- 0.1, 1.3 +/- 0.4, 1.5 +/- 0.3 and 2.4 +/- 0.3 ng/ml, respectively. The means of the peak plasma cortisol concentrations in the 3 cows after the ACTH challenge were 14.0 +/- 1.5, 17.0 +/- 2.5, 23.3 +/- 3.0, and 33.3 +/- 7.0 ng/ml, respectively. The effects of the doses, time after treatment, and their interaction on the plasma progesterone concentrations after the ACTH challenge were significant (P<0.01). Likewise, the effects of the doses, time after treatment, and their interaction on the plasma cortisol concentrations after the ACTH challenge were significant (P<0.01). The mean AUC values for the plasma progesterone and cortisol concentrations after the ACTH treatments were also significantly affected by the dose of ACTH (P<0.01 and P<0.05, respectively). A significantly positive correlation was obtained between the peak plasma progesterone and cortisol concentrations after different doses of ACTH (r=0.7, P<0.05). The results suggest that lactating dairy cows are capable of secreting a significant amount of adrenal progesterone, reaching up to the minimal concentration necessary to cause suppression of estrus in response to 12 IU ACTH (P<0.01). The concomitant plasma cortisol concentration was 23.3 ng/ml.  相似文献   

9.
There is a need to improve the lean tissue content of ruminant animals destined for meat production. Muscle fiber number is set during fetal development. The effect of undernutrition of pregnant ewes on subsequent muscle fiber characteristics of their offspring was investigated. The trial involved 32 pregnant ewes carrying twins. The ewes were allocated randomly to one of four groups: three different treatment groups (n = 8) and a control group (n = 8). The diet of the treatment groups was dropped to 50% of their daily requirement to support the ewe and allow for conceptus growth for varying periods before being returned to 100% of their daily requirement until term. Group d 30-70 ewes were fed 100% of their daily requirement until d 30, the diet was then decreased to 50% until d 70; it was then returned to 100% of their daily requirement until term. Group d 55-95 ewes were similarly restricted from d 55 through 95, and Group d 85-115 ewes were restricted from d 85 through 115. The control group was fed 100% of their daily requirement to support the ewe and allow for conceptus growth throughout gestation. After parturition, the lactating ewes were fed a normal commercial diet. On d 14 (after parturition), the lambs were slaughtered and the LM, semitendinosus (ST), and vastus lateralis (VL) were dissected and snap frozen. The immunochemical determination of myosin heavy-chain slow (MHC-slow) and myosin heavy-chain fast (MHC-fast) proteins was measured by immunoprobing of Western blots. The number of fast and slow fibers and the diameter of these fibers also were measured in each muscle sample by histochemical techniques. Decreased maternal nutrition before fiber formation (d 30 through 70) was observed to change the muscle characteristics of the newborn lambs. These lambs had significantly fewer fast fibers (P < 0.001) and significantly more slow fibers (P < 0.001) in both the LM and VL compared with the other groups. Maternal nutrient restriction at the other periods had no effect on the number of muscle fibers in the newborn lambs; however, a decrease (LM, P < 0.05; VL, P < 0.01; ST, P = 0.08) in muscle weight was observed in the lambs born to the ewes restricted between d 85 and 115 of gestation compared with the other groups. This study has shown that decreased maternal diet before muscle fiber formation will alter the muscle fiber development in the fetus.  相似文献   

10.
Thirty-eight pregnant Suffolk ewes were assigned randomly to a control group or implanted with approximately 2 g of testosterone propionate (TP) when they were between d 40 and 60 of gestation. Implants were removed 3 wk prior to lambing. Five ewe lambs born to implanted ewes and ten ewe lambs born to nonimplanted ewes were utilized in this experiment. Ram lambs were not used in this trial. No differences (P greater than .10) were observed for fecal, urinary and total N excretion and amount of N absorbed. Nitrogen retained (percentage of N intake and g/d) was higher (P less than .05) in prenatally androgenized ewe lambs than in control ewe lambs. Plasma insulin concentrations averaged 99% higher (P less than .05) in prenatally androgenized ewe lambs. Plasma insulin-like growth factor I (IGF-I) concentrations averaged 29% higher (P less than .06) in ewe lambs treated prenatally with testosterone. Nonesterified fatty acid (NEFA) concentrations averaged 41% higher (P less than .05) in prenatally androgenized ewe lambs. Significant (P less than .05) treatment x time effects were observed in plasma thyroxine, glucose and urea N concentrations of prenatally androgenized vs control ewe lambs. These significant modifications in the plasma metabolite and endocrine status could be an important element of the physiological mechanism(s) by which prenatal androgenization improves growth performance and leanness of ewe lambs.  相似文献   

11.
The aim of this study was to investigate the impact of ewe genetic merit on ewe performance and efficiency parameters. The study consisted of three genetic merit groups (New Zealand [NZ], High Irish, and Low Irish) and ran from 2016 to 2019, inclusive. Each genetic merit group contained 30 purebred Suffolk and 30 purebred Texel ewes, which were selected based on their maternal genetic indexes in their country of origin, namely Ireland (€uro-star Replacement index) or New Zealand (New Zealand Maternal worth). Ewe body condition score (BCS), ewe body weight (BW), milk yield, milk composition, dry matter intake (DMI), and efficiency parameters were all analyzed using linear mixed models. Ewe BW was similar across all genetic merit groups at each time point (P > 0.05). In comparison to both High and Low Irish ewes, NZ ewes had a higher BCS at mating, mid-pregnancy, lambing, week 10 post-lambing (PL, P < 0.05). Ewe BW change was similar across genetic merit groups, except between mating and mid-pregnancy where ewe BW loss was greater for NZ ewes than Irish ewes (P < 0.05) and between weeks 6 PL and 10 PL, where NZ ewes gained BW and High and Low Irish ewes lost BW (P < 0.01). Ewe milk yield, milk fat, total solids, and gross energy content were superior for milk produced by NZ ewes at week 6 PL in comparison to milk produced by High Irish and Low Irish ewes (P < 0.01). NZ ewes produced a greater quantity of milk solids/kg of BW at week 6 PL compared with High Irish ewes (P < 0.01), whereas Low Irish ewes did not differ from either NZ or High Irish (P > 0.05). Low Irish ewes had a greater daily DMI than High Irish ewes in late lactation (week 10 PL, P < 0.05) and had a greater DMI/kg of ewe BW compared with the High Irish ewes at the same time point (P < 0.05). NZ ewes weaned a litter BW equivalent to 60.4% of their mating BW, which was more than the Low Irish ewes who weaned 57.1% of the ewe’s BW at mating (P < 0.01), whereas the High Irish ewes did not differ from either the NZ or Low Irish ewes at 59.3% of the ewe’s BW at mating (P > 0.05). This study presents a range of parameters across ewes of high and low genetic merit, demonstrating the ability to achieve gains through selection of animals of high genetic merit. Sheep producers should consider genetic indexes as a tool to assist in the decision-making process of selecting replacement ewes and/or breeding rams, once satisfied the animal is correct, and meeting the breeding objectives of the system.  相似文献   

12.
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   

13.
Objectives were to estimate effects of sire breed (Dorset, Finnsheep, Romanov, Texel, and Montadale), dam breed (Composite III and northwestern whiteface), mating season (August, October, and December), ewe age (1, 2, and 3 yr), and their interactions on reproductive traits of F1 ewes. A total of 1,799 F1 ewes produced 3,849 litters from 4,804 exposures to Suffolk rams during 35-d mating seasons over 3 yr. Ewes were weighed at breeding. Conception rate and ewe longevity (present or absent at 42 mo of age) were determined. Number born and litter birth weight were recorded, and number and weight at weaning and 20 wk of age were analyzed separately for dam- and nursery-reared litter mates. Total productivity through 3 yr of age for each ewe entering the breeding flock was calculated as the sum of 20-wk weights for dam- or nursery-reared lambs. Interactions of sire breed x mating season, sire breed x ewe age, and mating season x ewe age were generally significant, whereas interactions of sire breed, mating season, and ewe age x dam breed were seldom detected. Interactions of sire breed x mating season were often due to changes in rank as well as magnitude, indicating the importance of matching sire breed to a specific mating season. The number born to Dorset-, Texel-, and Montadale-sired ewes was not affected by dam breed; however, Finnsheep-sired ewes out of northwestern whiteface dams were more prolific than Finnsheep-sired ewes out of Composite III dams, and the opposite situation existed for Romanov-sired ewes. Least squares means of sire breeds (P < 0.001) for total productivity of dam-reared lambs were 98.5, 103.5, 106.9, 124.6, and 154.9 kg/ewe entering the breeding flock for Texel, Dorset, Montadale, Finnsheep, and Romanov, respectively. Superior reproduction of Romanov-sired ewes was due to greater conception rate and prolificacy for each mating season and ewe age, as well as greater ewe longevity. Total productivity of F1 ewes by Composite III dams (125.6 kg) was greater (P < 0.001) than for ewes born to northwestern whiteface dams (109.7 kg), and the effect of mating season increased (P < 0.001) from August to October to December. Litter weight at 20 wk of age of 2- and 3-yr-old ewes was similar but greater (P < 0.001) than for 1-yr-old ewes. Experimental results provide comprehensive information about the appropriate use of these breeds in crossbreeding systems to meet specific production-marketing objectives.  相似文献   

14.
Objectives were to estimate effects of sire breed (Dorset, Finnsheep, Romanov, Texel, and Montadale), dam breed [Composite III (CIII) and northwestern whiteface (WF)], mating season (March and May), and their interactions on reproductive traits of mature F1 ewes in spring mating seasons. A total of 1,099 F1 ewes produced 1,754 litters of 2,995 lambs from exposures to Suffolk rams during March and May mating seasons in 1995 through 1999. Fertility rate and ewe longevity were measured. Number born and litter birth weight were recorded, and number and weight at weaning and 20 wk of age were analyzed separately for dam- and nursery-reared litter mates. Total productivity from 4 to 6 yr of age for each ewe entering the breeding flock was calculated as the sum of 20-wk weights for dam-reared lambs and separately for nursery-reared lambs. Interactions of sire breed x mating season, ewe age x mating season, and ewe age x dam breed were often significant. Interactive effects of sire breed and mating season on fertility rate (P < 0.001) were primarily due to differences in magnitude. Fertility rates of sire breeds for March and May matings, respectively, were 92 and 89% for Romanov, 91 and 72% for Finnsheep, 90 and 52% for Texel, 88 and 52% for Montadale, and 83 and 62% for Dorset. Sire breed x mating season also affected number born (P < 0.03); March and May values were 2.12 and 2.05 for Romanov, 2.00 and 1.94 for Finnsheep, 1.39 and 1.41 for Texel, 1.37 and 1.51 for Montadale, and 1.37 and 1.55 for Dorset, respectively. Interaction of sire breed x dam breed on fertility rate (P < 0.01) was due to change in rank as well as magnitude. Romanov- and Dorset-sired ewes out of CIII dams had greater fertility rates than Romanov- and Dorset-sired ewes out of WF dams. The opposite situation existed for ewes by Finnsheep, Texel, and Montadale sires. Differences between dam breeds (CIII and WF) in total productivity of dam-reared lambs were not detected, whereas ewes exposed in March (78 kg) were more productive (P < 0.01) than those exposed in May (68 kg). Means of sire breeds for total productivity of dam-reared lambs were 47, 65, 70, 70, and 111 kg for Texel, Montadale, Dorset, Finnsheep, and Romanov, respectively (P < 0.001). Superior reproduction of Romanov sired ewes was primarily due to greater fertility rate and prolificacy at each mating season and ewe age. Use of Romanov-crossbred ewes would increase fertility during spring mating, an important constraint of the sheep industry.  相似文献   

15.
Active immunization of sheep of the Dala breed against androstenedione caused a mean increase in number of lambs born (live-born and stillborn) of 0.29 (p less than 0.01). In yearlings the difference was 0.43 lambs (p less than 0.01) and in older ewes 0.23 lambs (p less than 0.1). Five of the older immunized ewes gave birth to quadruplets while none in the control group gave birth to more than 3 lambs. In older ewes there was an increase in the number of stillborn lambs. In young immunized ewes the mean ewe production, registered as total live weight of lambs in the autumn, was 11.3 kg higher than in control animals. This difference was however not significant (p less than 0.1).  相似文献   

16.
Peripubertal ewe lambs (44.3 +/- 1.1 kg of initial BW) were used in a 2 x 3 factorial design to test the effects of plane of nutrition (diet) and stage of gestation on maternal visceral tissue mass, intestinal cellularity, crypt cell proliferation, and jejunal mucosal vascularity. Singleton pregnancies to a single sire were established by embryo transfer, and thereafter ewes were offered a control (Control) or high (High) amount of a complete diet (2.84 Mcal/kg and 15.9% CP; DM basis) to promote slow or rapid maternal growth rates. After d 90 of gestation, feed intake of the Control group was adjusted weekly to maintain BCS and meet the increasing nutrient demands of the gravid uterus. Ewes were slaughtered at 50 d (n = 6 Control; n = 5 High), 90 d (n = 8 Control; n = 6 High), or 130 d (n = 8 Control; n = 6 High) of gestation. Ewes were eviscerated and masses of individual organs were recorded. The jejunum was sampled and processed for subsequent analyses. Final ewe BW for Control-fed ewes was similar at d 50 and 90 and increased (P = 0.10) from d 90 to 130 (46.0, 48.9, and 58.2 +/- 1.6 kg, respectively), whereas final BW increased (P 相似文献   

17.
To examine effects of nutritional plane and Se supplementation on colostrum quality and mammary development, individually fed, pregnant Rambouillet ewe lambs were allotted randomly to 1 of 6 treatments in a 2 x 3 factorial arrangement. Main effects included dietary Se level, which began at breeding (d = 0) [adequate Se (9.5 mug/kg of BW) vs. high Se (81.8 mug/kg of BW)], and plane of nutrition, which began at d 50 of gestation [60% (RES), 100% (CON), and 140% (HIGH) of requirements]. Upon parturition, lambs were immediately separated from dams and weighed. Three hours after lambing, colostrum yield was determined, and samples were obtained for components and immunoglobulin G (IgG) analysis. Ewes were slaughtered within 24 h of parturition, and mammary tissues were collected for determination of alveolar secretory epithelial cell proliferation index and luminal area. Gestation length was reduced (P < 0.01) in HIGH ewes compared with RES and CON ewes. Although birth weights were reduced (P < 0.01) in RES and HIGH compared with CON ewes, there was little effect of diet on placental size. Mammary gland weight was reduced (P /= 0.15) on mammary gland weight, colostrum quantity, or IgG concentration in pregnant ewe lambs. Improper nutrition from mid to late pregnancy in ewe lambs altered colostrum quality and quantity and reduced offspring birth weight, which may have negative implications for lamb health and survival during the early postnatal period.  相似文献   

18.
Experiments were conducted to compare the efficacy of synthetic progestogens administered by subcutaneous ear implant or intravaginal sponge to induce a synchronized estrus in adult ewes and ewe lambs and to evaluate reproductive performance (fertility and litter size) to breeding at the synchronized estrus. Experimental animals were representative of three strains maintained in total confinement and exposed to a synthetic light regimen which alternated at intervals of 4 mo from 18 h day length to 10 h day length/24 h. Treatments were applied at different times of the year at the end of a low light cycle. Implants contained Norgestomet (3 mg) impregnated in a polymethacrylate polymer (Implant H) or impregnated in a silastic polymer containing 1.05 (Implant S1), 1.78 (Implant S2) or 2.60 mg (Implant S3) Norgestomet, respectively. Intravaginal sponges contained 40 mg Fluorogestone Acetate. Implants or sponges were left in situ for 12 d and 500 IU pregnant mares' serum gonadotropin was injected im at the time of removal. Following treatment with Implant H, 96% of ewes were judged to be in estrus at 48 h after implant removal. Fertility of adult ewes and ewe lambs (6 to 7 mo of age at time of breeding) at the synchronized estrus were similar after implant H or sponge treatment, but litter size was higher (P less than .05) for adult ewes treated with sponges. The percentages of adult ewes marked by rams within 60 h after removal of silastic implants or intravaginal sponges were similar. There was a tendency for ewe lambs to be marked later than adult ewes and for adult ewes treated with Implant S1 and Implant S2 to be marked earlier than ewes treated with Implant S3 or sponges. Higher percentages (P less than .05) of adult ewes and ewe lambs lambed to breeding at the synchronized estrus after treatment with Implant S2 or Implant S3, respectively, than after treatment with Implants S2 or sponges.  相似文献   

19.
A resource population of ewes derived from Dorset and Romanov grandparents was generated over 5 yr to provide genotypic and phenotypic data to estimate effects of each callipyge genotype on component traits of reproduction. Effects on ovulation rate were estimated from data recorded by examination of ovaries from serially slaughtered ewe lambs (n = 174) born in 1994 and 1995. Productivity and longevity through 5 yr of age were recorded on a total of 265 F2 ewes produced in 1996 through 1998. Number of lambs born, birth weights, and weaning weights of lambs were calculated for each ewe. Weaning weight was recorded for each lamb and adjusted for age to 56 and 32 d for dam- and nursery-reared lambs, respectively. Longevity was determined as a binary trait based on the presence or absence of the ewe in the breeding flock at 5 yr of age. Ewes generated 937 records for breeding weight and 925 records for conception rate, which was determined on ewes exposed and still present at the start of each lambing season. Seven hundred seventeen records were analyzed for traits based on the number of ewes lambing. Genotypes for the causative callipyge mutation were determined using a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry assay. Each ewe was classified into 1 of 4 genotypes; NMatNPat, NMatCPat, CMatNPat, or CMatCPat, where N represents wild type and C represents the mutant allele. The mean ovulation rate of the ewe lambs genotyped NMatNPat was greater (P < 0.02) than that exhibited by NMatCPat; however, the estimated difference of 0.25 ovum in the ewe lambs did not affect the number born. The live weight of NMatCPat ewes at breeding was 2.5 kg less than that of other genotypes (P < 0.01). The callipyge genotype class did not significantly affect conception rates, fecundity, maternal ability, or ewe longevity. Maintaining a ewe flock to produce homozygous mutant rams for use in terminal sire mating systems presents no unusual problems from a reproduction standpoint.  相似文献   

20.
Three experiments were conducted to investigate experimentally the occurrence of periparturient nematode egg rise in ewes and the hormonal modulation of Haemonchus contortus infections. In the first experiment, fall-bred and winter-bred pregnant (n = 4 and 14, respectively) and nonpregnant (n = 5 and 29, respectively) ewes were treated with anthelmintic and were pastured together on fields that were contaminated with H contortus. Three weeks before lambing, all ewes were placed in concrete pens; fecal egg counts for the winter-bred group were obtained on alternate days. Pregnant and lactating ewes had significantly larger numbers (P less than 0.01) of H contortus eggs than did the nonpregnant controls 1 week before and after lambing. Lactating, fall-bred ewes had significantly (P less than 0.01) more adult worms in their abomasum through natural acquisition than the nonpregnant controls. In the second experiment, fall-bred and winter-bred, helminth-free, pregnant (n = 4 and 8, respectively) and nonpregnant (n = 3 and 15, respectively) ewes were inoculated on 5 alternate days, beginning 70 days after breeding with 20,000 infective H contortus larvae. The ewes were maintained on concrete pens throughout pregnancy. Fecal egg counts were significantly (P less than 0.05) greater in pregnant ewes, beginning 1 week before lambing until 1 week after lambing. Abomasums of lactating ewes from both lambing seasons yielded significantly (P less than 0.01) more adult worms at necropsy than nonpregnant ewes. In the third experiment, ewes were ovariectomized (n = 15) or sham-operated (n = 9); half of the control ewes were bred.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

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