Theses and Dissertations at Montana State University (MSU)
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Item Genomic, microbial, and linear relationships between residual feed intake, dry matter intake, average daily gain, and post weaning weights in range sheep(Montana State University - Bozeman, College of Agriculture, 2023) Schaub, Daniel James; Chairperson, Graduate Committee: Christian J. PosberghOver forty years, United States sheep producers have selectively bred range sheep for larger post-weaning weights using estimated breeding values. However, this has led to increased feed intake, prompting this study's objective to quantify the relationship between lamb growth estimated breeding values, feed intake, and feed efficiency. The study involved 40 Targhee and 40 Rambouillet ewe lambs weaned at four months and put on a GrowsafeTM feeding system for a 56-day experimental period, with ewes weighed weekly and at the start and end of the trial. Residual feed intake was calculated using body weights, average daily gain, and daily feed intake measurements. The ewe lambs' post-weaning weight estimated breeding value was associated to their phenotypic traits. These procedures were repeated when the same ewes were yearlings and at maintenance. The study found that while post-weaning weight estimated breeding values predicted dry matter intake (P<0.05), they lacked association with residual feed intake (P>0.05) in both experimental periods. However, the ewe's post-weaning weight estimated breeding value predicted mid-trial body weight in both periods (P<0.05). Thus, while selecting higher post- weaning weight animals may increase feed usage due to larger body size, it does not affect feed efficiency. Comparing the residual feed intake between the two experimental periods, growth residual feed intake measurements did not predict residual feed intake in maintenance. Therefore, caution should be used when utilizing residual feed intake from the growth period as an indicator of feed efficiency in maintenance. The study also examined rumen microbial profiles in sheep between the two experimental periods. Methanogenic archaea were relatively increased within the growth experimental period, where a pelleted diet was used, and cellulolytic bacteria were increased in the maintenance experimental period, where hay was provided. Since methanogens are associated with decreased feed efficiency, diet may play a role in changing a sheep's microbiome towards more feed efficient bacteria. Finally, a genome-wide association study found the Dmrt2 gene associated with DMI and RFI in maintenance. The Dmrt2 gene may regulate muscle and bone development in the early embryo, affecting feed efficiency in sheep later in life.Item Influence of supplementation on the productivity of ewes grazing improved pasture and suckling twins(Montana State University - Bozeman, College of Agriculture, 1988) Frey, Ana LidiaItem The effect of aureomycin upon lamb mortality and body weights and the effect of delayed feeding upon weaning weights(Montana State University - Bozeman, College of Agriculture, 1957) Bassett, James WilburItem The effect of Aureomycin in pelleted or whole grain creep rations fed to suckling lambs : the effect of Thyroprotein, Thiouracil, and Stilbestrol on gains of fattening lambs(Montana State University - Bozeman, College of Agriculture, 1956) Daley, Charles A.Item Production of two-year-old ewes(Montana State University - Bozeman, College of Agriculture, 1957) Colman, Kenneth L.; Chairperson, Graduate Committee: J. L. Van HornThe purpose of the investigation of these data was to explore the possibilities of relationships existing between the body weights of the ewes during their early life and their subsequent lamb and wool production as two-year-olds. The effects of environmental influences, such as type of birth and age at weaning, on the growth of ewe lambs and their production as two-year-olds were studied. The growth of two-hundred and fifty-nine ewes was measured by body weights taken at irregular intervals from birth to twenty-three months of age. Records of the individual lamb and wool production of these ewes were tabulated with the body weights. Results showed that the effect of type of birth and age at weaning, on body weights of ewe lambs was reduced as the lambs progressed toward maturity from weanling age. It was also found that the birth weights, weaning weights, and fall yearling weights of the ewes were significantly related. The fall yearling weight of the ewes was most indicative of two-year-old lamb and wool production. A significant relationship was found between the birth weights of the Rambouillet ewes and the pounds of lamb born per ewe as two-year-olds. The relationship between the birth weights of the Targhee ewes and the pounds of lamb born per ewe was not significant nor was this relationship significant for the birth weights of the Columbia ewes and the pounds of lamb born per ewe. The early single-born lambs were consistently lighter at birth than the late single-born lambs; however, at weaning time, the early single-born lambs were consistently heavier than the late single-born lambs. The average daily gain of the early single-born lambs and the late single-born lambs was about the same. The weaning weights of the ewes and their yearling fleece weights were significantly and positively related. The difference between the yearling fleece weights of the ewes and their two-year-old fleece weights was significant, the yearling fleece weights being the heaviest. It is evident from this study that valuable genetic breeding stock may be lost if suitable precautions are not taken to adjust for environmental conditions affecting the size of ewe lambs at weaning time when most replacements are selected. According to these data and that published previously by other workers, a sounder method of selecting higher producing replacements is to retain a larger number of ewe lambs at weaning and to make final selections at fall yearling age. Since production factors are closely related to body weight at fall yearling age, the heavier ewes of similar breeding will be better producers than the lighter ewes if selections are made at this age.Item Lamb selection by index(Montana State University - Bozeman, College of Agriculture, 1949) Williamson, Leslie O.Item Palatability, creep feeding and fattening studies with lambs(Montana State University - Bozeman, College of Agriculture, 1960) Montgomery, Charles E.Item Influence of colostrum from safflower supplemented ewes on lamb cold tolerance and lamb growth(Montana State University - Bozeman, College of Agriculture, 2008) Robinson, Brenda Lee; Chairperson, Graduate Committee: Rodney Kott; Patrick G. Hatfield (co-chair)Five hundred, ninety-seven and 643 white face range ewes were used in a 2 year study, respectively, in a 3-way factorial arrangement to determine effect of supplemental linoleic oil on lamb serum metabolites, thermogenesis and lamb growth. During the last 45 ± 4 days of gestation ewes were group fed a daily supplement of either 0.23 kg·ewe-1·d-1 whole safflower seed (SS) or 0.34 kg·ewe-1·d-1 whole barley (C). Colostrum was collected from each supplement treatment and pooled according to treatment. At parturition, twin born lambs received either SS or C pooled colostrum. One h postpartum, lambs were placed in a 0°C dry cold chamber for 30 min. and lamb rectal temperature was recorded at one min intervals. Blood samples were taken prior to and after cold exposure. Lamb weights were taken at birth, turnout and weaning for growth. There was no difference (P > 0.10) in body temperatures between lambs born to ewes supplemented with SS vs. C or between lambs given pooled colostrum form SS or C supplemented ewes. At 0 minutes lambs born to SS supplemented ewes had lower glucose (P = 0.05), total protein (P = 0.05) and NEFA (P = 0.003) and higher BUN (P = 0.03) than lambs from C supplemented ewes. Lambs from SS supplemented ewes had lower NEFA (P = 0.01) after cold exposure (30 minutes). Total protein concentration was similar in year 1 but lower (P < 0.01) in year 2. Concentrations of aGP were higher in lambs from SS supplemented ewes at both 0 and 30 min in year 1. Lambs from SS ewes had higher (P < 0.01) blood aGP levels at both 0 and 30 min in year 1 than in year 2. No differences (P > 0.30) were detected between lambs from SS ewes vs. C for changes in any blood metabolites measured during cold stress period. No differences (P > 0.12) were detected for average date of birth, number of lambs born, number of lambs present at turnout and weaning or for weight of lambs at turnout or weaning for ewes receiving either SS or C supplements.Item Thermogenesis, serum metabolites and hormones, and growth in lambs born to ewes supplemented with docosahexaenoic acid(Montana State University - Bozeman, College of Agriculture, 2010) Keithly, Jennifer Irene; Chairperson, Graduate Committee: Patrick G. Hatfield.Neonatal lamb mortality is a major factor effecting profitability in the sheep industry. Lamb thermogenesis and immunocompetence are key elements in neonatal lamb survival. Research has shown an increase in lamb vigor, when ewes were supplemented during late gestation with algae-derived docosahexaenoic acid (DHA). However, the impact of DHA on lamb thermogenesis and immunocompetence has not been investigated. Eighty twin-bearing Targhee ewes were assigned randomly to 1 of 2 supplemental treatments to determine the effects of feeding (DHA) to ewes during late gestation and early lactation on lamb thermogenesis, immunocompetence, serum metabolites and hormones, and lamb growth. Treatments within supplements were: 1) 12 g/ewe daily of the product DHA Gold in the form of algal biomass (ALGAE), and 2) no DHA (CONTROL). Treatment supplements were individually fed daily during the last 30 d of gestation and pen fed (6 pens/treatment, and 6 or 7 ewes/pen) during the first 38 d of lactation. One h after lambing and before nursing, twin-born lambs were weighed, bled via jugular puncture, and placed in a dry cold chamber for 30 min (0°C). Lamb rectal temperatures were recorded every 1 min. After 30 min, lambs were removed from the cold chamber, bled, warmed for 15 min, and returned to their dam. Ewes were bled and colostrum samples collected 1 h postpartum. Ewe and lamb sera were assayed for glucose, non-esterified fatty acids (NEFA), cortisol, leptin and anti-Parainfluenza Type 3 (PI³) titers. Lamb rectal temperature, glucose, NEFA, cortisol, leptin, anti-PI³ titers, and birth weights did not differ between treatments. Thirty-eight-d BW was greater (P = 0.03) in lambs born to CONTROL-supplemented than lambs born to ALGAE-supplemented ewes; however, the colostrum of ALGAE-supplemented ewes had a greater specific gravity (P = 0.05), indicating greater IgG concentrations, than colostrum of CONTROL-supplemented ewes. Supplementation of DHA during late gestation and early lactation had a negative impact on lamb BW and did not affect indices of lamb thermogenesis, but may have improved IgG concentrations in ewe colostrum.