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Thesis (Ph. D.)--Sverges lantbruksuniversitet, 2001. / Based on 4 previously prepared or published papers reprinted here. Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 2010. / Title from document title page. Document formatted into pages; contains viii, 65 p. : col. ill. Includes abstract. Includes bibliographical references.

Thesis (M.S. in animal sciences)--Washington State University, December 2009. / Title from PDF title page (viewed on Jan. 15, 2010). "Department of Animal Sciences." Includes bibliographical references (p. 67-77).

The control of milk protein production was investigated utilising two different approaches. The first model is one of intravenous infusion of atropine. Atropine, which decreases milk protein yield, has been theorised to act either by decreasing blood somatotropin (ST) concentration or by decreasing blood amino acid (AA) concentration. Thus, the first experiment was designed to test which mechanism, or both, is responsible for the effects on milk protein yield. Five lactating dairy cows were assigned to the following treatments which were administered intravenously: Saline (CONT), atropine (ATR), ATR + ST, ATR + AAs, and ATR + ST + AAs. Atropine treatment failed to decrease plasma ST concentration but did decrease plasma alpha-amino nitrogen concentration. Atropine treatment decreased milk protein yield but neither ST, AAs, nor ST + AAs were able to maintain milk protein yield at the CONT level when infused with ATR. It is clear that the treatments tested are not directly responsible for the decrease in milk protein yield due to ATR. Therefore, neither ST, AAs, nor ST + AAs appear to have direct control of milk protein production. Plasma insulin (INS) concentration was decreased and plasma IGF-I concentration was not decreased by ATR treatment. Insulin, therefore, presents itself as a candidate for direct control over milk protein synthesis. The second model is one of monitoring endocrine response to abomasal infusion of AAs mimicking the profile of milk protein with selective deletion of certain AAs. Six lactating dairy cows were subjected to the following treatments: Saline (negative control, NC), AAs (positive control, PC), PC minus methionine (PC-Met), PC minus lysine (PC-Lys), PC minus histidine (PC-His), and PC minus the branched-chain AAs (PC-BCAAs). All endocrine factors studied (ST, INS, glucagon & IGF-I) were affected by treatment. Plasma IGF-I concentration responded similarly, except for the PC-Met treatment, to milk protein yield (Weekes and Cant, 200

Construction of the Karakoram Highway (KKH) has led to more rapid socio-economic change in areas close to highway than in more remote areas such as the Gilgit Ghizer Region (GGR) in Northern Pakistan. In the present study the aim was to compare the livestock enterprise in the developed region (i.e KKH) with the less developed area (i.e. GGR). A 2 x 3 factorial design was used with two geographical transects and three cropping zones and one village being studied within each cell. Nutritional inputs to, and productive outputs from, the livestock system, together with their interaction were investigated. Wheat straw (48%), lucerne (24%) and maize stover (13%) were the dominant feeds. Cereal crop residues and lucerne were main sources of energy and protein respectively. The main livestock species kept were cattle (51%), goats (31%), sheep (10%) and donkeys (8%). Overall, 65% of the herd was made up of non-productive animals. Feed sufficiency was 33% greater in the KKH transect (P < 0.05) and feed offered was 33% higher per unit liveweight in the KKH transect (P < 0.05). Stored feeds and herd weight per household were higher in the GGR transect (P < 0.05). Daily milk yield and calving rate were higher (P < 0.05) in the KKH (2.9 l/d and 0.82) compared with the GGR transect (2.3 l/d and 0.52). However proportions of fodder and cattle sold were higher (P < 0.05) in the GGR transect (16.5 % and 8%) than in the KKH transect (8.5% and <1). Overall, performance was higher in the KKH transect and this was related to herd size being better matched with feed resources. Larger herds in the GGR transect reduced animal performance but detrimental effects appeared to be partly masked by differences in the quality of summer pasture resources between transects.

The cumulative effects of different levels of annual energy intake over the first two parities on two breeds of beef cow (Aberdeen Angus: small size and low milk potential and Simmental: large size and high milk potential) were assessed for productive and reproductive traits during the early post-partum period. Heifers from each breed were allocated to one of two levels of annual energy intake (mean daily intakes equivalent to 705 and 820 kJ/kg M^0.75 metabolisable energy) in a 2 (genotype) x 2 (feeding level) x 4 animals (replicates) factorial design each year. Animals were housed and individually fed throughout the year. The diets were designed to represent energy intakes while grazing during the summer and conserved feeding during the winter. Body condition, live weight, milk yield, blood metabolite and gonadotrophin concentrations, and follicular development were measured during the post-partum period. LH release was measured (15 min intervals for 8 h) in relation to dominant follicle development. Simmental cows gave higher milk yields and lost more body condition score during the post-partum period. Low body condition scores at calving and high losses of body condition during the post-partum period were associated with decreased LH pulse frequency and size of dominant follicle, and longer intervals from calving to first ovulation. LH pulse frequency increased towards ovulation but mean LH concentration and LH pulse amplitude did not . LH pulse frequency appeared to be higher during the dominance phase although this observation was not statistically significant. LH pulse frequency was lower and dominant follicle size smaller during the second than first parity. In conclusion, the data indicate that, during the early post-partum period, reproductive efficiency of Simmental cows appears to be lower than Aberdeen Angus cows when offered similar amounts of metabolisable energy per kg metabolic live weight.

Thesis (M.Sc.(Agric.))--University of Western Australia, 2005.

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Vita. Includes bibliographical references (leaves 83-94). Also available on the Internet.