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Biomedical subjects

C F Parker

Publications and source records attributed to C F Parker.

At least 19 recordsLinked to original sources
PubMed1991

Energy utilization and organ mass of Targhee sheep selected for rate and efficiency of gain and receiving high and low planes of nutrition.

Two experiments were conducted to examine changes in usage of energy and visceral organ mass in Targhee lambs selected on the basis of improved rate and efficiency of growth. In Exp. 1, Targhee ram lambs from a breeding line selected for improved growth rate and feed efficiency and a control line that was maintained without selection for 20 yr were provided with either a high (ad libitum) or low (maintenance) plane of nutrition. Rams were slaughtered and weights of the visceral organs were recorded. Analysis of variance, using a factorial model with BW as a covariant, was used to examine effects of lines of breeding, plane of nutrition, interaction between line of breeding and plane of nutrition, and days on feed. Weights of liver, kidneys, rumen, abomasum, and small and large intestines from lambs receiving a high plane of nutrition were, respectively, 39, 25, 12, 28, 40, and 31% greater than weights of those tissues in lambs receiving a low plane of nutrition. Ruminal weights were 13% greater for rams from the select line of breeding than for those from the control line. In Exp. 2, seven Targhee ewe lambs from the select line and eight from the control line were examined for differences in heat production and energy usage by indirect open circuit respiration calorimetry using a completely randomized design. Fasting heat production of lambs from the select line was 7.8% greater than that of lambs from the control line. Partial efficiencies of ME used for maintenance and tissue accretion were not different between lines of breeding.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Nutritional Physiological Phenomena↗
PubMed1989

Genetic parameters for ewe productivity traits in the Columbia, Suffolk and Targhee breeds.

Estimates of repeatability and heritability were obtained for the following productivity traits of ewes: litter weight at birth (LWB) and weaning (LWW), litter size at birth (LSB), litter size alive at birth (NBA), litter size at weaning (LSW), neonatal survival rate (SRB) and preweaning survival rate (SRW). Phenotypic and genetic correlations were estimated for litter traits. The data set contained 6,394 ewe breeding records from three state stations over 10 yr on 1,731 ewes that were the progeny of 488 sires among three breeds (Columbia, Suffolk and Targhee). Pooled intra-station estimates of repeatability ranged from .11 to .22 for LWB and LWW among the three breeds. For litter size at birth, number born alive and litter size at weaning these estimates varied from .09 to .17 and for the survival traits (SRB and SRW) the variation was from .11 to .20. Intra-station estimates of heritability for the three breeds varied from .12 to .28 for LWB and LWW, and for LSB, NBA and LSW estimates varied from .05 to .35. Heritability estimates for survival traits (SRB and SRW) were low, ranging from .00 to .14. Phenotypic correlations among LWB, LWW, NBA and LSW ranged from .35 to .92 among the breed-station subclasses, with higher correlations occurring where a part-whole relationship existed. The study suggests that selection of ewes with high litter size at birth or at weaning and(or) litter weight at birth or at weaning will genetically improve total litter weight at weaning per ewe lambing.

Animals↗
PubMed1988

Genetic-associated resistance to foot rot in selected Targhee sheep.

Three Targhee rams obtained from the Ohio Agricultural and Experimental Station had been identified as foot rot resistant on the basis of results of challenge exposure. In the first breeding trial, when rams were bred to 20 foot rot-susceptible ewes, the percentages of foot rot-resistant offspring from the 3 foot rot-resistant rams were 68, 82, and 100, compared with 55 and 60 for foot rot-resistant offspring from 2 known foot rot-susceptible rams. In the second year, the foot rot-resistant rams were mated with ewes of unknown foot rot status. The foot rot-resistant status of their lambs was compared with that of range-raised lambs whose parents' foot rot status was unknown. During the first year, challenge exposure to the disease consisted of confinement of the lambs in moist or wet pens with sheep affected with the naturally acquired disease. This protocol was repeated for lambs born during the second-year breeding trial. In addition, the right front foot of each lamb was inoculated with a broth culture of Bacteroides nodosus. During the second year, when data that included infected feet from all lambs were analyzed, 41% of the progeny of the foot rot-resistant rams and 17% of the offspring of parents of unknown foot rot status were unaffected by the disease. When the B nodosus-inoculated foot was not included in the analysis, however, 61% of the progeny of the foot rot-resistant rams and 29% of the others were unaffected. The resistance to foot rot undoubtedly is hereditary. The mechanism of resistance may be in the interdigital skin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Melatonin advances june breeding and fall lambing in range and farm-flock type ewes.

Influence of melatonin on reproductive performance was evaluated by randomly allotting Polypay-type ewes to four treatments: controls in drylot, melatonin-treated ewes in drylot, controls on range, and melatonin-treated ewes on range. An additional group of Targhees and Rambouillets was randomized by breed as control ewes or melatonin-treated ewes to test effect of melatonin in range ewes. All ewes were supplemented with 0.34 kg/head alfalfa-barley (1:1) pellets from 1600 to 1630 h daily, from April 15 to June 30. Ewes maintained on range received no further supplementation, while ewes in drylot received alfalfa pellets for maintenance. Melatonin was fed at 10 mg hd(-1) d(-1) in the pellet to designated ewes in drylot or on range. Three rams were put with each group of ewes on June 1 and rotated among groups at 7-d intervals during the first 30 d of breeding to reduce sire differences. After the first 30 d, ewe groups were combined with all rams. Melatonin induced (P<0.01) an earlier onset of estrus (approximately 17 d) as indicated by earlier lambing dates in Polypay-type, Rambouillet, and Targhee ewes managed on spring range. Melatonin also increased (P<0.01) the number of ewes that conceived during the first 30 d of breeding (June) for both management treatments (drylot and range) and for all breeds.

Journal Article↗
PubMed1988

Genetic and environmental factors affecting immunoglobulin G1 concentrations in ewe colostrum and lamb serum.

Presuckle colostral samples and lamb serum samples taken 36 h postpartum were assayed for immunoglobulin G1 (IgG1) concentration (mg/ml) using single radial immunodiffusion. Breeds sampled included Polypay (P), Rambouillet (R), Targhee (T), Columbia (C), Finnish Landrace (F) and Finn crosses (Fx). Sources of variation examined in IgG1 concentration in colostrum (dam trait) included dam's sire breed, dam's sire, age of ewe and number of lambs born. All sources of variation were statistically significant. Least-squares means of IgG1 levels for sire breed were 80, 64, 67, 64, 72 and 69 mg/ml for P, R, T, C, F and Fx breed groups, respectively. A fetal stimulus may exist to increase the mass of IgG1 in colostrum available for multiple births (61, 69 and 77 mg/ml for single, twin and triplet, respectively). Ewe age was a significant source of variation because of a high mean concentration of IgG1 in the yearling's colostrum (100 mg/ml), whereas only slight differences occurred between the other age groups (65 to 67 mg/ml), except for the 7-yr older group (53 mg/ml). Sources of variation examined in IgG1 concentration of lamb serum at 36 h postpartum (lamb trait) included lamb's sire breed, lamb's sire, age of dam, birth type and sex, with dam's colostral IgG1 concentration and day born as covariates. Sire within breed, birth type and the two covariates were significant. Least squares means for sire breed were 36, 32, 33, 32, 31 and 32 mg/ml of serum for P, R, T, C, F and Fx groups, respectively. Lamb serum IgG1 decreased as birth type increased. The heritability of IgG1, estimated by paternal half-sib analyses, was .19 +/- .12 for colostrum and .18 +/- .06 for lamb serum.

Animals↗
PubMed1988

Influence of concentration, duration and route of administration of melatonin on reproductive performance of spring-mated polypay and polypay-cross ewes.

The effects of exogenous melatonin on reproductive performance of 737 Polypay and Polypay-cross ewes were evaluated during a late March and April breeding period. Different concentrations (2 or 10 mg) routes of administration (fed vs implanted) and durations of administration (20 or 40 d before breeding) were studied. Estrus was synchronized in all ewes using 60 mg medroxyprogesterone acetate (MAP) in a vaginal pessary. Number of mature ewes lambing/ewe present at lambing was increased (P less than .05) nearly 20% by implanting for 40 d with melatonin (75%) or by feeding either 2 (72%) or 10 mg (73%) melatonin for 40 d before spring breeding compared with untreated control ewes (54%) or ewes implanted for only 20 d before breeding (58%). Date of lambing, number of lambs born/ewes lambing and number of lambs born alive/ewe lambing were not altered significantly by treatments. Number of yearling ewes (n = 166 for ewes 1.5 yr old at lambing time) lambing/ewe present at lambing was lower (P less than .01; 26%) than that of mature ewes (n = 381, greater than or equal to 2.0 yr; 68%). We concluded that feeding 2 or 10 mg melatonin or implanting melatonin for 40 d enhanced reproductive performance and effectively overcame the restrictions of seasonality of breeding in mature ewes. In yearling ewes, 10 mg melatonin increased the number of ewes lambing.

Administration, Oral↗
PubMed1987

Level of alimentation and line of breeding on oxygen uptake by ovine jejunal mucosa.

Targhee rams from a selected and control line of breeding were provided with the same diet at either 100 or 40% of ad libitum feed intake levels for 28 days. The rams were killed in a serial fashion over a 35-day period. A sample of the jejunum mucosa was taken, and O2 consumption rates with and without ouabain were measured. Total O2 consumption and ouabain-sensitive respiration rates of the jejunal mucosa taken from rams of the select line were greater than for samples taken from the control rams. Line of breeding did not influence the percent of the total O2 consumption that was ouabain sensitive and the proportion of the jejunum that was mucosa. Differences in rates of total and ouabain-sensitive O2 consumption attributed to level of feed intake were not detected as significant. Both the percentage of the total respiration rates that was ouabain sensitive and the proportion of the jejunum that was mucosa were greater for rams fed at high intake levels compared with rams fed at low intake levels. Thus both breeding sheep on the basis of improved growth potential and level of alimentation influenced aspects of jejunal mucosa respiration that was Na+-K+-adenosinetriphosphatase dependent.

Animals↗
PubMed1985

Prefreezing and post-thaw semen characteristics of five ram breeds collected by electroejaculation.

Rams representing five breeds were electroejaculated twice weekly, during a three-week collection period. Ejaculates were evaluated for volume and concentration before freezing and for rate of motility and percentages of motile and abnormal cells both before and after freezing. Interactions between breed and collection period were evident (P<0.05) for semen volume and post-thaw values for rate of motility and percentage motile cells. Breeds differed (P<0.05) in these traits during some periods. In contrast, pre-freezing observations of rate of motility, percentage motile and abnormal cells and post-thaw percentage abnormal cells did not differ (P>0.15) among breeds. Sperm concentration per ejaculate tended to vary (P=0.11) among breeds. Semen characteristics frequently varied across collection periods. Rams within a breed differed (P<0.01) in all semen traits except post-thaw rate of motility and percentage motile cells. Semen was negatively affected by the freezing and thawing procedure. Ram within a breed and ejaculate within ram should be considered when selecting electroejaculated semen for freezing and subsequent use in artificial insemination.

Journal Article↗
PubMed1985

Effects of number of lambs suckled and supplemental protein source on lactating ewe performance.

Effects of number of lambs suckled and supplemental protein source on ewe performance were determined. Lactation performance of ewes nursing twin or triplet lambs was compared in Exp. 1 and 2. In Exp. 1, ewes giving birth to and nursing triplets produced 21% (P less than .05) more milk/unit metabolic body weight, were 10% more efficient in the conversion of feed to milk and produced 26% (P less than .05) more kg of lamb/ewe on d 42 of lactation than did ewes giving birth to and nursing twins. In Exp. 2, lactation performance of ewes giving birth to triplets and rearing only two lambs was compared with performance of ewes giving birth to triplets and rearing three lambs. Ewes rearing three lambs produced 28% (P less than .08) more milk and were 26% (P less than .05) more efficient in converting feed to milk than were those rearing two lambs. This suggests that direct nursing stimulation of the mammary gland is responsible for the improvement in milk production observed when ewes nurse additional lambs. The efficacy of slowly degradable protein sources for improved lactation was studied in Exp. 3 and 4. When blood meal was fed to twin-rearing ewes at 3.30% of the diet (25% of total dietary protein), milk production was greater (3,176 vs. 2,506 g/d, P less than .05) and efficiency of milk production was greater (1.05 vs .79 g milk/g feed, P less than .05) than when ewes were fed supplemental soybean meal. Ewes in this experiment fed supplemental meat and bone meal also tended to produce more milk than those fed soybean meal.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Population Groups↗
PubMed1984

Epidemiologic approach to the control of sheep nematodes.

Epidemiologic approaches to parasite control, with reduced reliance on the use of anthelmintics, were studied in 6 groups of weaned lambs and 4 groups of suckling lambs grazing fertilized pastures. Strategies tested included prophylactic treatments in the spring, provision of safe pastures, treat-and-move strategies, and winter (prelambing) treatment of ewes. Suppressive treatment with a non-benzimidazole drug was used as a production yardstick against which the epidemiologic approaches were judged. Suppressive treatment with a benzimidazole drug was used to determine the drug resistance status of the flock. The success of each strategy was evaluated by measurements of body weight, wool growth, fecal egg counts, pasture larval counts, and total worm burdens. Prophylactic treatments in the spring were just as effective as suppressive treatments throughout the entire grazing season and resulted in significant (P less than 0.001) increases in weight gain. Effective parasite control also was obtained by moving ewes and lambs to safe pastures (low infectivity) in May, and resulted in significant (P less than 0.001) increases in weight gain. A treat-and-move strategy led to significant (P less than 0.001) increases in weight gain until September, but then a loss of weight in October, suggesting the need for a double treat-and-move strategy in the case of late-marketed lambs. The value of winter (prelambing) treatments for ewes also was demonstrated. Suppressive treatments with a benzimidazole drug confirmed the presence of benzimidazole-resistant nematodes.

Animals↗
PubMed1984

Control of hypobiotic and benzimidazole-resistant nematodes of sheep.

In studies comprising a total of 117 naturally infected crossbred lambs, it was found that lambs turned out to spring pasture were exposed to immediate infection with overwintered Ostertagia, Nematodirus, and Trichostrongylus spp, but did not acquire Haemonchus contortus infection until July. With all species, there appeared to be only one major disease-producing generation of worms per year; it was responsible for serious worm burdens and clinical disease from July onward. High frequencies of hypobiosis (arrested development) were demonstrated in H contortus (98% to 100%), Ostertagia circumcincta (89% to 96%), and Nematodirus filicollis (77% to 90%) by late November; Trichostrongylus spp comprised most of the adult (egg-laying) worm population at that time. The onset of hypobiosis appeared to be induced by seasonal stimuli rather than by host-immune responses. The results of these studies showed benzimidazole resistance to be a major problem. In the first year, fenbendazole (5 mg/kg) reduced worm burdens by 46% and 20% in September and December, respectively. In December of the second year, levamisole (8 mg/kg) reduced worm burdens by 99%, thiabendazole (44 mg/kg) by 55%, fenbendazole (5 mg/kg) by 47%, and fenbendazole (15 mg/kg) by 11%. Levamisole was highly efficient (99%) against adult worms, hypobiotic worms, and benzimidazole-resistant worms. Ostertagia circumcincta was strongly resistant to the benzimidazole drugs at all dosages tested, while H contortus and Trichostronglylus spp were partially resistant. There was no evidence of reversion of resistant worms to susceptibility on this farm, even though benzimidazole drugs had not been used for 9 years.

Animals↗
PubMed1983

Increased litter size in gilts by intrauterine infusion of seminal and sperm antigens before breeding.

Three experiments were conducted to evaluate the effect of exposure of the uterus to semen at least 3 wk before breeding on subsequent reproductive performance. In Exp. 1, uterine exposure to semen was performed three times. At least 3 wk elapsed between each treatment. Control gilts received saline infusion. All gilts were bred by artificial insemination using semen from the same boars used for semen treatment. At farrowing, significantly more (10.35 vs 8.39) pigs/litter were produced by semen-treated gilts than controls. However, due to a disease outbreak (porcine parvovirus) during the last two-thirds of the farrowing period, live pigs born and litter size at 2 wk were not statistically different between the two groups. Gilts that farrowed were rebred and no difference in their reproductive performance for second litters was noted. For Exp. 2 and 3, a single semen treatment was given using freeze-thaw killed semen at estrus before breeding. Within both Exp. 2 and 3, semen-treated gilts had a larger average litter size, but no significant differences were detected. When data for nondiseased animals in Exp. 1 and animals in Exp. 2 and 3 were pooled, it was found that total pigs born (P less than .01), live pigs born (P less than .01) and live litter birth weight (P less than .1) were all greater in semen-treated gilts than in controls. Thus, these results indicate that reproductive efficiency in gilts can be improved by intrauterine treatment with boar semen before insemination to elicit conception.

Animals↗