Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
Browse
14 results
Search Results
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 Grazing, feed intake, and milk production differences in beef cows of varying efficiency classification and size(Montana State University - Bozeman, College of Agriculture, 2018) Williams, Alyson Rose; Chairperson, Graduate Committee: Timothy DelCurto; C.T. Parsons, J.G.P. Bowman, D.L. Boss and T. DelCurto were co-authors of the article, 'The influence of weaning weight ratio and cow size on feed intake behavior, milk yield, and milk constituents' submitted to the journal 'Journal of animal science' which is contained within this thesis.; S.A. Wyffels, C.T. Parsons, J.G.P. Bowman, D.L. Boss and T. DelCurto were co-authors of the article, 'The influence of weaning weight ratio and cow size on winter grazing and supplement intake behavior' submitted to the journal 'Journal of animal science' which is contained within this thesis.Metrics that identify beef cow efficiency in extensive rangeland environments has long been desired in both beef cattle research and production settings. However, research is limited relative to matching cattle metrics to western production systems. Previous research has suggested the ratio of calf weight weaned to cow weight, or weaning weight ratio, is an accurate estimate of cow efficiency. Furthermore, milk production has been attributed to influence calf pre-weaning average daily gain. Few studies have evaluated how cow type or cow characteristics influence grazing distribution and supplement consumption on native landscapes. The objectives of this study were to assess cow feed intake, grazing behavior, supplement intake, and milk production differences between cows of differing weaning weight ratio and body weight classification. Individual cow average daily feed consumption, average daily feeding bout duration, number of visits per day, and total time spent eating per day were collected during a feed intake period and a supplement intake period. Total distance traveled and time spent grazing were collected on individual cows with global positioning system collars. Milk samples were analyzed for fat, solids not fat, total solids, protein, and lactose content, and milk yield was calculated as the change in calf weight following a weigh-suckle-weigh procedure. High weaning weight ratio cows consumed more feed when expressed on a g/kg bodyweight basis (P < 0.001) but did not differ in supplement consumption (P > 0.10). High weaning weight ratio cows produced more milk both in total kg (P < 0.03) and when expressed as /kg bodyweight (P < 0.001). Heavy bodyweight cows tended to consume more feed than light bodyweight cows (P < 0.09) but neither bodyweight group ate more supplement than the other (P > 0.10). High weaning weight ratio cows spent an hour longer grazing per day than low weaning weight ratio cows (P < 0.02). Total distanced traveled per day did not differ (P > 0.10). Results suggest weaning weight ratio and cow size are not accurate metrics of cow efficiency and the use of weaning weight ratio may unintentionally favor cows with higher milk production and higher feed requirements.Item Utilization of biuret and urea as affected by feeding interval and energy level(Montana State University - Bozeman, College of Agriculture, 1970) Armitage, Jesse GeorgeItem The forage intake of supplemented cows grazing winter foothill rangelands of Montana(Montana State University - Bozeman, College of Agriculture, 1985) Turner, Mark EstesItem Influence of starch digestion rate on feedlot performance and site of starch digestion in beef steers fed high concentrate diets of corn or barley(Montana State University - Bozeman, College of Agriculture, 2000) Milner, Timothy JamesItem The effects of diallyldiethylstibestrol, diallylhexestrol and diethylstilbestrol on fattening steers and heifers(Montana State University - Bozeman, College of Agriculture, 1960) Doty, John T.Item Fecal output by calves of Tarentaise, Hereford and crossbred cows under range conditions(Montana State University - Bozeman, College of Agriculture, 1998) Miller, Eric ThomasItem Physiological and behavioral responses of cows on Montana foothill range to winter and supplement(Montana State University - Bozeman, College of Agriculture, 1986) Dunn, Roger WilliamItem Maternal biological efficiency of beef cattle(Montana State University - Bozeman, College of Agriculture, 2000) Stevens, Jeffrey DavidItem Influence of different forms of methionine on gain, intake, and ruminal parameters of heifers grazing improved pastures(Montana State University - Bozeman, College of Agriculture, 1991) Sorensen, Sharon Joyce