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1.
Suffolk and Targhee ewes (30 each) with single or twin lambs were used in four periods beginning in late gestation and continuing through weaning to evaluate breed differences in milk production, lamb BW, and DMI by ewes and lambs. In Periods 1 (late gestation) and 2 (early lactation), ewes (Period 1) and ewes with lambs (Period 2) were individually penned, fed .45 kg of barley x ewe(-1) x d(-1) and allowed ad libitum access to chopped alfalfa. Ewes and lambs grazed native range in Periods 3 and 4. Grazed forage DMI was estimated using chromic oxide. Estimates of milk production were obtained by handmilking. Average lamb age was 4, 45, and 73 d at the beginning of Periods 2, 3, and 4, respectively. Milk production tended (P = .20) to be greater for Suffolk than for Targhee ewes. Targhee ewes produced 85% more (P = .001) wool than Suffolk ewes. From 33 d prepartum to 89 d postpartum, Suffolk ewes consistently weighed more (P = .001) than Targhee ewes. Suffolk ewe BW loss (-.15 kg/d) was greater (P = .01) than Targhee ewe BW loss (-.02 kg/d) from 33 d prepartum to 6 d postpartum. From 6 to 89 d postpartum BW gain did not differ (P = .69; .05 kg/d) between breeds. From birth to 89 d postpartum, Suffolk lambs consistently weighed more than Targhee lambs (P = .003). From birth to 89 d postpartum, ADG was greater for Suffolk than for Targhee lambs (P = .006). Targhee ewes consumed 25% more (P = .01) feed over the course of the study than did Suffolk ewes. Grazed forage DMI by Targhee lambs was 26% greater (P = .01) than DMI by Suffolk lambs. When meat production is the primary income from sheep, one potential advantage of Suffolks compared with Targhees is more rapid gain with less feed intake.  相似文献   

2.
The U.S. National Sheep Improvement Program (NSIP) began in 1987 to provide within-flock genetic evaluations for the American sheep industry. An evaluation of operating procedures and methodology for NSIP began in 1993 and has resulted in across-flock, multiple-trait EPD for three breeds: Targhee, Suffolk, and Polypay. Traits reported in the across-flock analyses included direct and maternal effects on weaning weight in all breeds, postweaning weight at 120 d in Suffolk and Polypay and at 365 d in Targhee, greasy fleece weight in Targhee and Polypay, and wool fiber diameter in Targhee. Number born per ewe lambing was also evaluated in single-trait analyses for all breeds. Genetic parameters were derived separately for each breed. Important genetic antagonisms include an unfavorable genetic correlation of .51 between fleece weight and fiber diameter in Targhee and a genetic correlation of -.55 between direct and maternal effects on weaning weight in Polypay. Estimates of genetic trends between 1987 and 1995 were consistent with perceived breed roles. In Targhee, direct and maternal effects on body weights increased, fiber diameter declined, fleece weight was maintained, and number born declined. In Suffolk, direct effects on body weight increased, but number born and maternal effects on weaning weight did not change. In Polypay, number born and maternal contributions to weaning weight increased, but direct genetic merit for body weight declined. Prospective enhancements to NSIP include methods for genetic evaluation of performance in accelerated lambing and of carcass leanness and development of breeding objectives and selection aids for various production systems.  相似文献   

3.
Data are presented on tail length of various breeds or crosses of sheep and various combinations of Mouflon X Rambouillet breeding. Mouflons sheep had 11 coccygeal vertebrae, and Rambouillet had 18-24. Others were intermediate between these types. Finewool sheep (Merino or Rambouillet) had longer tails than medium wool (Dorset, Suffolk or Hampshire), crossed, or Rambouillet breeds. Heritability estimates for tail length of Rambouillet were 0.387 (intra-sire regression), 0.344 (half-sib method), and 0.706 for inter se matings in a population containing some Mouflon breeding. In the Rambouillet breed, tail length was shown to be correlated with various measures of wool production. However, this relationship was low and only wool covering and staple length were significant. The significance of this to the development of long tails in animals under domestication is discussed.  相似文献   

4.
A study was carried out at the International Livestock Research Institute (ILRI) Debre Berhan Research Station in Ethiopia from 1992 to 1995 to compare the peri-parturient rise (PPR) in faecal nematode egg counts (FEC) in ewes of two indigenous sheep breeds. A total of 1439 Menz and 1347 Horro ewes were single sire mated following oestrus synchronization to lamb in the wet and dry season. Three ewe treatment groups were constituted as mated/lactating/undrenched; mated/lactating/drenched; unmated/undrenched for three wet and three dry lambing seasons. All ewes grazed naturally contaminated pasture. Levels of faecal egg output were monitored at mating, 3 months after mating, 2 weeks before lambing, 4, 8 and 12 weeks post-lambing. A significant PPR in FEC occurred 2 weeks before lambing and peaked at 4 weeks post-parturition in ewes lambing just before the beginning of the dry season (October/November). There was no significant increase in FEC when lambing occurred before the onset of the long rainy season (May/June). The PPR in this study was associated with both lactation and seasonal availability of third-stage infective larvae on pasture. There was no consistent breed difference in FEC during the six sampling periods from mating to weaning. Faecal cultures and worm counts from both breeds confirmed the presence of Longistrongylus (Pseudomarshallagia) elongata, Trichostrongylus spp.and Haemonchus contortus. The role of the peri-parturient rise of FEC in ewes in gastrointestinal nematode transmission is discussed.  相似文献   

5.
To investigate the effectiveness of four selection protocols for improving reproduction in sheep, we evaluated nine selection lines and two random-bred control lines for lamb and wool production. Results were based on 25,026 dam and 30,628 lamb records from Rambouillet (R), Targhee (T), Columbia (C), and Polypay (P) sheep collected from 1976 through 1988. Phenotypic trends over years were positive (P < .01) for most reproductive traits, body weight, wool grade (coarser grades), and lamb weaning weight in nearly all selected lines. Small positive trends for both random-bred control lines indicated there were improvements in management and(or) environment during the period. Small but significant phenotypic declines in fleece weights occurred in most lines, including controls. Substantial genetic gains (P < .01) in litter weight weaned (120 d), net reproductive rate (lambs weaned divided by ewes mated), prolificacy, body weight, and weaning weight were made in nearly all selected lines. There were also small but significant improvements in milk score in most lines. There were significant genetic declines and improvements in fleece weights; however, the average genetic change in fleece weight for lines selected for litter weight weaned was negligible. Genetic improvement in litter weight weaned was attributed approximately 37% to prolificacy, 27% to percentage of lambs weaned, 17% to lamb weaning weight, 12% to fertility, and 7% to ewe viability from breeding to lambing. On average, selection based on independent culling levels (litter weight weaned plus yearling body weight), yearling body weight, or early puberty was only 85, 67, or 59%, respectively, as effective as that based solely on litter weight weaned for improving litter weight weaned. The net value of the average (over all breeds) annual increase in production per ewe resulting from selection for litter weight weaned accumulated over 12 yr to an estimated $11.40 and $21.51 annually for genetic and phenotypic increases, respectively.  相似文献   

6.
An eight-year study was conducted to define the epidemiology of gastrointestinal nematode infection in Suffolk and Gulf Coast Native (Native) breeds of sheep, and to determine if the Native sheep is more resistant to infection. For the initial three years, each breed grazed separate pastures where anthelmintic treatments were administered to individual animals on a salvage basis. For the last five years, both breeds grazed concurrently; anthelmintic treatments were administered to individual animals on a salvage basis for the first three years, and to all animals, when treatment criteria were met, for the last two years. The fecal egg count (FEC) and blood packed cell volume (PCV) were monitored, and tracer lamb nematode burdens were determined. Overall, FEC for both breeds increased in the spring (periparturient rise) for most years and in the summer for all years. Under separate grazing conditions, Native ewes and lambs had consistently lower infection levels than Suffolk ewes and lambs. During the haemonchosis season (June-September) each year, Suffolk ewe and lamb PCV decreased, and Native ewe and lamb PCV remained relatively stable. The salvage treatment protocol resulted in 27 treatments for Suffolk and one for Native ewes; similarly for lambs, 13 for Suffolk and zero for Native. Tracer lambs grazed with their respective breed, and the FEC and mean total nematode burden corresponded with the pattern of infection for their respective breed. The predominant nematodes found in Suffolk and Native tracer lambs were Haemonchus contortus and Trichostrongylus spp., respectively. Under concurrent grazing conditions, the same seasonal repeatable pattern of infection was present and was exhibited by both breeds, with the Native ewes and lambs being consistently and significantly (p < or = 0.05) lower for FEC and higher for PCV. The salvage treatment protocol resulted in 57 and zero treatments for Suffolk and Native ewes, respectively; for lambs, 46 and 11. Tracer lamb nematode burdens again corresponded to their respective breed pattern of infection, with H. contortus and Trichostrongylus spp. being predominant in Suffolk and Native lambs, respectively. Data from all tracer lambs showed a relatively low level of hypobiosis (H. contortus only), and, although there was no consistent hypobiosis season, the tendency was for a higher level to occur in the fall. These results showed that the classic repeatable seasonal pattern of gastrointestinal nematode infection occurred in both breeds of sheep, and that Native sheep were more resistant to infection (specifically H. contortus) than Suffolk sheep.  相似文献   

7.
Methods were developed and incorporated into a previously published computer model to predict ME intake and calculate biological efficiencies in terms of grams of empty BW (EBW) and fat-free matter (FFM) gained/megacalorie of ME consumed from weaning to slaughter. Efficiencies were calculated for steers from F1 crosses of 16 sire breeds (Hereford, Angus, Jersey, South Devon, Limousin, Simmental, Charolais, Red Poll, Brown Swiss, Gelbvieh, Maine Anjou, Chianina, Brahman, Sahiwal, Pinzgauer, and Tarentaise) mated to Hereford and Angus dams, grown under nine backgrounding systems, finished at either a low (1.0 kg) or high (1.36 kg) ADG, and slaughtered at 300 kg carcass weight, small or greater degree of marbling, and 28% carcass fat. Backgrounding systems were high ADG (.9 kg) for 111, 167, or 222 d, medium ADG (.5 kg) for 200, 300, or 400 d, and low ADG (.25 kg) for 300 or 400 d, and 0 d backgrounding. The high ADG finishing system was more biologically efficient than the low ADG finishing system, and generally backgrounding systems were less biologically efficient than direct finishing after weaning (0 d backgrounding). Large-framed breeds were more efficient at the constant carcass weight and carcass fatness end point, and breeds that achieved the marbling end point at low levels of carcass fatness were more efficient at this end point. Some small-framed breeds gained EBW more efficiently but gained FFM less efficiently than some of the large-framed breeds. Variation in efficiency between genotypes was greatest with 0 d backgrounding and decreased in the other backgrounding systems.  相似文献   

8.
The aim of this study was to examine the effect of the FecBB fecundity gene on plasma concentrations and pituitary content of growth hormone (GH) in sheep. No differences were found between homozygous carriers (BB) and non carriers (++) of the FecBB gene with regard to pituitary GH contents in both ovariectomized and intact ewes. However, ovariectomized ewes had higher levels of pituitary GH than intact ewes (P < 0.01). There were no differences between FecBB genotypes with respect to plasma concentrations of GH in 6-year-old ovariectomized ewes bled every 10 min for 12 h or in ram lambs bled weekly during their first year of life. GH levels in the rams decreased until week 27, increased to a peak at week 31 then decreased before increasing again at week 43. Mean plasma GH concentrations in the ewe lambs bled weekly for a year decreased until week 19 then remained at approximately this level for the remainder of the year. Mean GH plasma concentrations in the ram lambs were higher than in the ewe lambs (P < 0.001). Ewe lambs that were homozygous for the FecBB gene had lower body weights (P < 0.05) and had higher levels of GH (P < 0.01) than non carrier ewe lambs during their first year. Before the average age of first behavioural oestrus (36 weeks) GH levels in the ewe lambs were negatively correlated with body weights (r = -0.69, P < 0.001, n = 22). When body weight was included as a covariate in analysis of variance the genotype difference in ewe lamb plasma GH concentrations was no longer significant.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

9.
Antiserum to a high-sulphur protein (SCMK-B2) from wool was purified to obtain the immunoglobin G fraction, and this was labelled with horse-radish peroxidase. The labelled antibody was then applied to sections of sheep skin embedded in glycol methacrylate in order to locate the distribution of high-sulphur protein within the lower hair shaft. Regions containing the highest concentration of high-sulphur protein were the cuticle of the hair shaft and the keratogenous zone of the cortex.  相似文献   

10.
The interactions between T. congolense infection and nutritional supplements on onset of puberty and age at first lambing were observed in 24 young Djallonké ewes. As experimental design, a randomised complete block design was used with four treatment combinations, of which two were kept on a restricted diet (L), the remainder on an unrestricted diet (H) and half of each nutritional group being infected with T. congolense (LI and HI), the remainder serving as controls (LC and HC). Infection with T. congolense took place at an average age of 6 months and 15 days. Mortality due to trypanosome infection was zero and clinical symptoms were not obvious. Intensity of parasitaemia and packed cell volume (PCV) drop following trypanosome infection were similar in both infected groups (HI and LI). High dietary supplementation resulted temporarily in a better haematopoietic response following trypanosome infection, measured as a macrocytic anaemia. Dry matter intake (DMI) was significantly depressed in the HI group immediately following infection. Trypanosome infection had a negative effect on live weight gain during the chronic phase, with the difference being most obvious in the HI group (interaction diet x infection; p< or =0.05). Whereas trypanosome infection had no significant effect, high supplementary feeding significantly reduced the age at first cycling. Age at first lambing was similarly reduced by the diet. Trypanosome infection tended (p< or =0.09) to delay age at first lambing with a mean difference of 31.5+/-22.4 days between infected and controls. Interactions between diet and infection for age at first cycling/lambing were not significant, indicating these effects were just additive. Neither birth weights nor growth rates of offspring born to the experimental animals were significantly affected by previous trypanosome infection, nor by the diet of the dam. In contrast, lamb mortality up to 3 months of age was significantly increased by infection of the dam and most losses arose in group LI. In conclusion, the effects of trypanosome infection on puberty and age at first lambing were indirectly mediated through depression of growth rates. Nutritional supplementation enabled a better erythropoietic response to T. congolense infection and better offspring survival rates but resulted in more depressed weight gains. The results however clearly indicated the delaying effect of insufficient feeding on onset of puberty and reproductive performance in young Djallonké sheep.  相似文献   

11.
We investigated heat tolerance and growth rate in two trials under ambient conditions in central Florida. Trial 1 (1994) involved 38 Brahman (B), 21 Senepol (S), 19 B x Angus (A), 20 S x A, and 20 Tuli (T) x A heifers. Trial 2 (1995) involved 13 A, 35 B, 30 S, 23 B x A, 17 S x A, and 28 T x A heifers. Measurements were made on three consecutive weeks during the hotter and cooler seasons of each year and included rectal temperature (RT, degrees C), respiration rate (RR, bpm), temperament score (TS; 1 = very docile, 5 = very aggressive), blood packed-cell volume (PCV), and plasma cortisol concentration (CORT). Data for RT were transformed (log10 [RT - 37]) before analysis. On the hottest date in Trial 1, log10 RT was not different between B (.39 +/- .011) and B x A (.37 +/- .016) or between T x A (.35 +/- .015) and B x A, but log10 RT was lower (P < .05) in S x A (.30 +/- .015) than in either S (.35 +/- .015) or T x A. On all dates in Trial 1, RR was lower (P < .05 to .001) and PCV was higher (P < .05 to .001) in B than in B x A. There were few differences in TS except on two dates when B scored higher (P < .01 to .001) than B x A, and these differences were associated with higher (P < .05) CORT in B than in B x A. Using initial BW as a covariate, adjusted ADG (kg) of T x A (.52 +/- .023) was not different from adjusted ADG of B x A (.57 +/- .024) or S x A (.54 +/- .023). On the hottest date in Trial 2, log10 RT and RR were higher (P < .001) in A (.59 +/- .017, 74 +/- 2.7) than in B (.47 +/- .010, 39 +/- 1.6), S (.42 +/- .011, 50 +/- 1.8), and crossbred heifers (.47 +/- .011, 60 +/- 1.8; .43 +/- .014, 55 +/- 2.4; and .50 +/- .012, 48 +/- 2.0 for T x A, S x A and B x A, respectively), and RR was higher (P < .001) in B x A than in B. On the coolest date in Trial 2, RR was slightly lower in B (32 +/- .5) than in A(34 +/- .7, P < .01) and B x A (36 +/- .6, P < .001) and was associated with higher PCV in B than in A. On both dates, TS and CORT were higher (P < .01) in B than in A. In Trial 2, adjusted ADG (kg) was higher (P < .01) in B (.43 +/- .017) than in A (.32 +/- .033), higher (P < .001) in S (.45 +/- .018) than in A, and higher (P < .001) in crossbreds (B x A [.53 +/- .023] + S x A [.44 +/- .025] + T x A [.46 +/- .019]) than in A. These data indicate that heat tolerance in F1 crosses of tropically adapted breeds (Tuli, Senepol, Brahman) with a temperate breed (Angus) is similar to heat tolerance displayed by purebred tropical breeds (Senepol, Brahman).  相似文献   

12.
Hair from smokers and non-smokers has been exposed in a dynamic exposure chamber to air nicotine concentrations ranging from 1.5 to 45 and from 20 to 2000 micrograms/m3 for 8 weeks and 72 hr, respectively. Accumulated hair nicotine was quantified by GC/MS. Hair was also collected for direct measurements of nicotine in 0-2, 2-4 and 4-6 cm segments from the scalp. Human hair showed a high affinity for air nicotine and the chamber experiments revealed a linear relationship between the initial hair uptake rates of nicotine and the duration of exposure at all air nicotine concentrations applied. Hair nicotine uptake rate decreased with time after 4 to 6 weeks exposure to 15 and 45 micrograms/m3 air concentrations of nicotine, but not to the 1.5 micrograms/m2 nicotine concentration. Ratio between the hair uptake rate of nicotine and the applied air concentration of nicotine decreased with increasing air concentrations of nicotine. Segment analysis of hair revealed an outward increasing gradient of nicotine in hair. Hair uptake pattern of air nicotine suggests the uptake to be governed by an equilibrium between nicotine in air and nicotine on the hair surface, possibly combined with a slower diffusion process of nicotine from the hair surface into the hair core. The hair segment analysis of nicotine indicates that environmental nicotine is the dominating contributor to the overall nicotine found in hair both from smokers and non-smokers.  相似文献   

13.
Two lines of White Leghorns that had undergone long-term selection for high (HH) or low (LL) antibody response to sheep red blood cell antigen(s) formed the nuclear lines for this experiment. Matings were made in a full diallel cross to produce in a single hatch from age-contemporary breeders the parental lines, reciprocal F1 and F2 crosses, and backcrosses for 16 progeny types. For males and females, there were parental line differences in BW to 42 d of age, after which there was decline between lines for males. Differences in BW between reciprocal F1 crosses and maternal heterosis declined with age, primarily reflecting dissipation of effects of egg weight. Heterosis of BW was dependent on the particular F1 cross and recombination effects were not important. At 50 d of age chicks were inoculated with either a 1 or 10% suspension of spleen extract from chickens infected with marble spleen disease virus (MSDV). A third group served as uninjected controls. Response to MSDV was evaluated by spleen weight 6 d after inoculation. Spleen weights relative to BW of control chicks were heavier for the HH than LL line with evidence from the crosses of sexlinkage and negative heterosis. Line LL chicks were more resistant to MSDV than Line HH chicks was F1 crosses intermediate to and different from either parental line with no evidence of heterosis.  相似文献   

14.
The effects that characteristics of forage-based diets on gut and liver energy use in sheep with ad libitum consumption were discussed, and practical consequences of diet and animal effects on splanchnic energy use were projected. Explained variation in portal-drained viscera (PDV) and hepatic energy use by sheep in recent experiments increased when independent variables were included in regressions on DE intake (DEI) (PDV: R2=33 vs 22%; liver: R2=48 vs 25%). The regression equations used were the following: PDV energy use, Mcal/d=-.0194 + (.1207 x DEI, Mcal/d) + (1.1173 x fecal NDF excretion, kg/d) - (.2860 x DEI x fecal NDF excretion) and hepatic energy use, Mcal/d=.0014 + (.0266 x DEI, Mcal/d) + (.3325 x PDV energy use, Mcal/d) + (.0745 x urea N hepatic net flux, mol/d) + (.0016 x BW, kg). Thus, gut digesta, as implied by fecal NDF excretion, seemed to influence PDV energy use in addition to the effect of DEI, and energy consumption by the liver seemed affected by PDV energy use and hepatic ureagenesis. A regression equation (R2=49%) for splanchnic bed energy use, expressed as a percentage of DEI, was 43.61 - (9.531 x DEI, Mcal/d) + (15.914 x fecal NDF excretion, kg/d) + (6.057 x urea N hepatic net flux, mol/ d). If physiological control of feed intake with effect of efficiency of energy metabolism is assumed, and if whole-body efficiency of energy metabolism with ad libitum intake is constant, then efficiency of energy metabolism in extrasplanchnic tissues decreases as level of ad libitum intake and the ratio of splanchnic bed energy use to DEI decrease. Therefore, animal characteristics (e.g., maturity, body condition, and biological type) and grazing conditions (e.g., forage mass) may affect feed intake by influencing heat production by peripheral tissues. In conclusion, an increased understanding of dietary influences on efficiency of splanchnic tissue metabolism may lead to enhanced efficiency of forage utilization and ruminant production systems.  相似文献   

15.
BACKGROUND: The long-term epilation of hair is the goal of several lasers and intense pulsed light systems. OBJECTIVE: The purpose of the study is to use the EpiLight Hair Removal System to assess long-term epilation and to assess its safety profile following a single treatment session. METHODS: Patients received a single treatment with the Epilight Hair Removal System after entering the patient's skin type, skin color, hair color, and hair density into the system's computer software. Treatment parameters include various wavelengths of light, pulse duration, pulse delay, and energy fluence. Thirty-seven subjects received a single treatment using one of four cut-off filters consisting of two to five pulses with energies of 34-55 J/cm2. RESULTS: The results of a single treatment show hair clearances occurring immediately and over a 12-week study period. Approximately 60% hair removal was noted at 12 weeks. CONCLUSIONS: The EpiLight Hair Removal System is an effective and safe method for long-term epilation of unwanted hair.  相似文献   

16.
Cumulative lifetime (five lamb crops) lamb production and wool production of 681 ewes were evaluated in this study. Lamb production and wool production from each ewe at the end of age 2, 3, 4, 5, and 6 yr were added to the previous year's production and analyzed within age of ewe. If a ewe failed to lamb, died, or was culled, it received a zero for that year and subsequent years. Main effects in the model included ewe breed and management system. Per ewe entering the study, Finn-Dorset-Targhee (FDT) ewes had a higher (P < .01) number of lambs born (7.42 vs 5.70), number of lambs weaned (5.39 vs 4.48), and total lamb weight weaned (131.7 vs 110.5 kg) than did Targhee ewes. Targhee ewes produced more (P < .01) wool (16.1 vs 13.6 kg) than FDT ewes. Range flock ewes had a higher number of lambs born (6.74 vs 6.38; P < .05), number of lambs weaned (5.39 vs 4.48; P < .01), and total lamb weight weaned (135.8 vs 106.5 kg; P < .01) than did farm flock ewes. Farm flock ewes produced more (P < .01) wool (15.2 vs 14.5 kg). A second analysis based on only those ewes retained at the start of each subsequent breeding season showed FDT ewes had a higher (P < .01) number of lambs born (9.96 vs 8.11), number of lambs weaned (7.61 vs 6.57), and total lamb weight weaned (183.8 vs 165.7 kg) after five lamb crops. Targhee ewes produced more (P < .01) wool (22.5 vs 17.6 kg). Farm flock ewes had a higher (P < .10) number of lambs born (9.18 vs 8.89) and produced more (P < .01) wool (21.1 vs 19.0 kg) than range flock ewes. Range flock ewes weaned more (P < .05) lambs (7.27 vs 6.92) and had more (P < .01) total lamb weight weaned (184.3 vs 165.2 kg) than farm flock ewes.  相似文献   

17.
Hair loss can be assessed objectively by examining a hair pull sample for stage of growth and hair shaft diameter, getting an estimate of average daily hair loss, and mapping scalp hair density. The history of the loss, the clinical picture, and the growth stage and diameter of the hair when lost all help to establish the type of loss. Hair regrowth occurs without treatment in most types of hair loss. There is as yet no effective treatment for pattern or senescent alopecia, although in women the loss can now be retarded somewhat.  相似文献   

18.
The objective of this study was to evaluate the effects of a long-term, low-calcium diet on fetal calcium metabolism and fetal skeleton development in ewes. Eleven pregnant sheep were assigned to two groups, fed either a diet low in calcium (0.26% total dry matter) or normal in calcium (0.8% total dry matter) for 2 months, starting at 60 days gestational age. The ewes fed the low calcium diet showed lower plasma levels of calcium and higher plasma levels of hydroxyproline, parathyroid hormone, and 1,25(OH)2D compared with the ewes fed the normal calcium diet. There were no differences in these variables between the two groups of fetuses. These observations suggest that the plasma components of calcium homeostasis measured in the fetal lamb in the present study are independent of the ewe and are not significantly affected by the presence of lowered maternal calcium for many weeks during pregnancy. Despite the ability of the fetus of the ewe on the low calcium diet to maintain relatively normal circulating plasma components of calcium homeostasis, long-term maternal hypocalcemia delayed fetal skeletal ossification as shown by histological examination of the fetal humerus. The fetal humerus from low calcium-fed ewes showed a lower proportion of bone versus cartilage (45.6 +/- 5.9 versus 57.4 +/- 4.6%, mean +/- SD) lower ash content (15.4 +/- 1.5 versus 17.4 +/- 1.0%), and lower specific gravity (1.19 +/- 0.2 versus 1.22 +/- 0.02) (P < 0.05) than the humerus from fetuses of normal calcium-fed ewes. This study shows that the long-term calcium intake of the ewe does affect fetal skeletal development, despite a lack of observable effects on fetal plasma concentrations of calcium or known calcium regulating hormones such as 1,25(OH)2D or parathyroid hormone.  相似文献   

19.
Seventy postpubertal Holstein replacement heifers were assigned to one of four treatments to assess effects of accelerated postpubertal growth on performance during first lactation. Heifers were fed control or accelerated diets from 10 mo of age until parturition, and breeding was initiated at 14 or 10 mo of age, respectively. Heifers were also subdivided into two breeding groups (target or delayed) based on normal AI breeding efficiencies. Heifers fed accelerated diets had a higher average daily gain (933 vs. 778 g/d) and calved earlier (21.7 vs. 24.6 mo) than did heifers fed control diets. Heifers fed accelerated diets had similar prepartum (10 d) BW, but lower wither height and postpartum BW, than heifers fed the control. For heifers fed accelerated diets, milk fat and milk protein yields were lower, and milk fat percentage was higher, at mo 1 and 2; milk fat percentage was lower at mo 3 to 7 of lactation. Delayed bred heifers calved later (approximately 2 mo), had higher prepartum and postpartum BW, and were taller at the withers than target bred heifers. Delayed breeding resulted in higher body condition scores at calving and a greater incidence of dystocia, but lactation performance was not affected. Accelerated postpubertal growth resulted in earlier calving at similar prepartum BW, but data for wither height, pelvic area, and postpartum BW suggested that heifers fed accelerated diets were smaller. Accelerated postpubertal growth and early calving reduced performance during first lactation, but the exact mechanisms could not be determined.  相似文献   

20.
Conducted 3 experiments with 53 gerbils to assess the conditions for ultrasonic emission. Exp I indicates that isolated Ss rarely emitted ultrasounds, males emitted at a higher rate than females, and emission rates ordinarily decreased with continual testing. Ultrasonic emissions were stimulated by olfactory cues from conspecifics. Exp II demonstrates that dominant males emitted more ultrasounds than subordinate males and responded to cues from anesthetized, shaved, or dead animals or from anesthetized animals in the dark. Exp III shows that body hair elicited ultrasounds from males unless organic materials were removed from the hair with chloroform. Hair was an effective stimulus at a distance only when an airstream blew the volatiles over the recipient. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   

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