Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1987. / Vita. Abstract. Includes bibliographical references (leaves 52-57). Also available via the Internet.

Milk yield of dairy cows is mainly determined by their nutrition and state of health. Dairy cows turn roughage into milk the most effectively. The assessment of the level of nutrition and the processing of silage and haylage was performed in operating conditions. Quality of roughage, technique of nutrition and its influence on milk yield in stanchion-tied stable were assessed. Data were observed over a peri-od of 3 years (2012 2015). The observation included Czech Fleckvieh Breed and Holstein Breed. Average daily yield data were monitored with all dairy cows, which were in lactation period during the observation. The gained data were entered into diagrams and charts and evaluated. The highest performance results have been achieved in 2015, the lowest performance results have been achieved in 2013.

Made available in DSpace on 2014-06-11T19:29:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2003Bitstream added on 2014-06-13T20:38:46Z : No. of bitstreams: 1 beltran_mp_me_botfmvz.pdf: 148138 bytes, checksum: 1776ee2d4797eee98e40fdd19aa6dc82 (MD5) / Este estudo avaliou o efeito de injeções de GnRH (hormônio liberador de gonadotrofina) ou hCG (gonadotrofina coriônica humana) no dia 5 após inseminação artificial (IA) nas taxas de concepção em vacas lactantes durante o verão. Vacas holandesas, n=158, produzindo 26±9 kg de leite/dia e 213±112 dias pós-parto (DPP), foram aleatoriamente distribuídas em 3 grupos: Controle (GC; n=52); GnRH (GG; n=55), 100 mcg IM. de gonadorelina (Cystorelinâ); e hCG (GH; n=51), 2500 UI IM de hCG (Vetecorâ). A temperatura retal foi verificada no momento da IA, e as amostras de sangue coletadas nos dias 5; 7 e 12 após IA para avaliar as concentrações séricas de progesterona (P4). A prenhez foi determinada entre os dias 42 e 49 após IA. Os dados foram analisados pelo procedimento MIXED do SAS, e foram incluídos no modelo efeitos do tratamento, ordem de lactação, produção de leite, temperatura retal no momento da IA e suas interações. O tratamento com GnRH ou hCG aumentou a P4 sérica (P<0,01). As concentrações séricas de P4 (ng/ml; média ± EPM) para GC, GG, e GH foram, respectivamente, no dia 5: 2,71±0,43; 2,45±0,44 e 3,23±0,45, no dia 7: 4,79±0,43; 4,15±0,44 e 5,75±0,45, e no dia 12 após IA: 5,21±0,43; 6,91±0,44 e 8,50±0,45. Devido ao aumento proporcional na concentração sérica de P4 entre os dias 5 e 7 após IA (GC: 77, GG: 69, GH: 77%; P<0,01) é provável que os tratamentos não tenham induzido o efeito luteotrópico no CL existente, porém devido ao grande aumento na P4 sérica no dia 12 nos animais tratados (GG: 112, GH: 87%; P<0,01) em relação aos animais controle (GC: 16%; P=0,31), provavelmente houve a indução de um novo CL. A temperatura retal média das vacas no momento da IA foi de 39,7°C e o tratamento com GnRH ou hCG aumentou as taxas de concepção (média ± EPM) nas vacas com temperatura retal abaixo de 39,7°C... / This study evaluated the effect of GnRH (gonadotropin releazing hormone) or hCG (human chorionic gonadotropin) injection on day 5 after artificial insemination (AI) on conception rates in lactating dairy cows during the summer. Holstein cows, 158, producing 26 ± 9 kg milk/d and 213 ± 112 days in milk, were randomly assigned to one of 3 treatments groups: control (CG: n=52); GnRH (GG: n=55), injection of 100 mcg i.m. of gonadorelin (Cystorelin®) and hCG (HG: n=51), injection of 2500 UI hCG i.m. (Vetecor®). Rectal temperature was checked at the moment of AI and blood samples collected on days 5, 7 and 12 after AI to evaluate serum progesterone (P4) concentrations. Pregnancy was determined between 42 and 49 d after AI. Data were analyzed by the MIXED procedure of SAS and were included in the model the effects of treatment, parity, milk production, rectal temperature at the moment of AI and interactions. Treatment with GnRH or hCG increased serum P4 (P<0,01). Serum P4 concentrations (ng/ml, mean±SEM) for CG, GG and HG were, respectively, on day 5 2.71±0.43, 2.45±0.44 and 3.23±0.45, on day 7, 4.79±0.43, 4.15±0.44 and 5.75±0.45 and on day 12 after AI, 5.21±0.43, 6.91±0.44, 8.50±0.45. Due to the proportional increase in serum P4 concentration from d 5 to 7 after AI (CG: 77, GG: 69, HG: 77%, P<0,01), it is likely that treatments did not have luteotropic effect on the existing CL, but due the higher increase in serum P4 on day 12 in the treated animals (GG: 112, HG: 87%; P<0,01) in relation to the control group animals (GC: 16%; P=0,31), probably induced the formation of a new CL. The average rectal temperature of cows at time of AI was 39,7°C. Treatment with GnRH and hCG increased conception rates (mean±SEM) in cows with rectal temperature below 39,7°C (CG: 10.1±0.075, n= 26, GG: 36.8±0.073, n=27, HG: 32.8±0.088%, n=21; p<.01)... (Complete abstract click electronic address below)

Target is to explore, if homeopatics or another unconventional ways could be used in medical treatment or in prevention of cow mastitis, and at the same time to find by the mesurement of microclimatics indicators if the climate in stable has influence on inflammations of lacteal gland.

Published research suggests that it might be beneficial to increase the amount of rumen undegradable protein (RUP) that passes out of the rumen, through manipulation of rumen fermentation to establish a lower rumen pH. To test this hypothesis, a study was conducted in which three ruminally cannulated Holstein cows, 722 kg ±25.6 kg fed three different diets (treatments) were used in a Latin square design experiment to determine effects of increasing levels of dietary concentrate on some rumen parameters and ruminal crude protein (CP) degradability. The in situ method was used to determine the ruminal protein degradability of sunflower oilcake, cottonseed oilcake and roasted soya. The three treatments differed in roughage:concentrate ratio, being 60:40 (Treatment UP 60), 45:55 (Treatment UP 45) and 30:70 (Treatment UP 30). Intake of dry matter (DM) (kg/day) did not differ between treatments. The mean rumen pH in cows receiving the three experimental diets differed and was 6.00, 6.27 and 6.44 for treatments UP 30, UP 45 and UP 60 respectively. The time (hours) below pH 5.8, which is considered to be the pH where fibre degradation is substantially negatively affected, was approximately 2.5 hours, but only on treatment UP 30. Mean rumen ammonia nitrogen (N) and total volatile fatty acid (VFA) concentrations did not differ among cows receiving different treatments but, cows fed treatment UP 30 had a lower ruminal acetic acid:propionic acid (A:P) ratio compared to the other treatments. There were no differences in ruminal CP degradation within the three feedstuffs when incubated in cows fed diets with different roughage:concentrate ratios. Results suggest that roughage:concentrate ratios ranging from 60:40 to 30:70, which resulted in mean pH values ranging from 6.4 to 6.0, did not affect ruminal CP degradation of sunflower oilcake, cottonseed oilcake and roasted soya. / Dissertation (MSc(Agric))--University of Pretoria, 2009. / Animal and Wildlife Sciences / unrestricted

Milk fever (parturient paresis / hypocalcaemia) is a metabolic disorder that usually occurs near parturition and at the onset of lactation in high producing multiparous dairy cows. Milk fever can indirectly contribute to an increased incidence of several diseases in early lactation. This study was conducted to compare two different feeding strategies to prevent milk fever, namely (i) the established concept of feeding a diet with a negative DCAD and (ii) a feeding strategy combining a negative DCAD supplement with 25-hydroxyvitamin D3 (25-OH-D3). Thirty dairy cows were used in a randomized block design and were selected and blocked by parity (second parity and later), 305 day mature equivalent milk production in the previous lactation and expected calving date. Within each of the 15 blocks, the cows were allocated to two experimental groups named DCAD and DCAD + HyD. Fifteen animals in the DCAD + HyD group received a daily oral dosage of 3 mg of 25-OH-D3. Plasma samples were collected from day 21 prepartum to 10 days postpartum and were analysed for 25-OH-D3, 1,25-dihydroxyvitamin D3, total and ionized calcium, phosphorus and magnesium. Samples were collected on day 21, 14, 10 prepartum and every second day to calving, 4 and 6 h postpartum and every second day up to day 10 after calving. Urinary samples for determination of macro minerals (calcium and phosphorus) were collected via manual stimulation on day 21, 14, 8 and 4 prepartum and day 4 postpartum. These samples were used to ensure that mild metabolic acidosis was achieved in both treatment groups. The metabolic acidosis was demonstrated by decreased urinary pH. Milk samples were collected on day 1, 4 and 10 postpartum and used for macro mineral (calcium and phosphorus) determination. This study did not achieve all of the expected results observed in similar experiments. No treatment differences could be detected for plasma Ca2+ concentrations (P>0.05) and the mean plasma Ca2+ concentrations were [1.086a mmol/L ± 0.010 (DCAD treatment) and 1.083a mmol/L ± 0.010 (DCAD + HyD treatment)] respectively.   Furthermore 1,25-(OH)2D3 plasma concentrations did not indicate any treatment differences (P>0.05). These results could be due to the fact that the experimental animals were not sufficiently challenged and therefore the combination of a low DCAD diet and Rovimix HyD did not influence the calcium homeostatic mechanisms as expected. A clear correlation between plasma 25-OH-D3 concentration and treatment duration was however demonstrated (P<0.001), indicating effective absorption of orally supplemented 25-OH-D3. Several authors demonstrated that feeding massive doses of vitamin D2 (30 million units) for extended periods led to clinical evidence of vitamin D toxicity. When 10 million IU of vitamin D3 were however administered intramuscularly within 10 days of parturition, a reasonable measure of protection against toxicity could be provided. It can be concluded from this study that longer feeding periods (± 21 days) than the proposed 10 days prior to calving can safely be implemented when feeding 3 mg 25-OH-D3 per animal per day (=240 mg Rovimix HyD 1,25%). Copyright / Dissertation (MSc(Agric))--University of Pretoria, 2012. / Animal and Wildlife Sciences / unrestricted

Thirty high-producing multiparous Holstein cows were used in a completely randomized block design to compare a lysine deficient total mixed ration, which was sufficient in methionine, to the same diet supplemented with a rumen protected lysine product. The CPM-Dairy prediction model was used to estimate the nutrient requirements and adequacy or deficiency of amino acids. During the 21-day prepartum transition period, cows were fed 4 kg (dry basis) of the lysine deficient diet plus Eragrostis curvula hay ad lib. After calving, cows were fed the lysine deficient diet for the first three weeks and were then blocked according to the average production from day 19-21. Fifteen cows were allocated to each treatment and blocked into 15 groups of two each. Data on production parameters were analyzed for all cows and also separately for cows in the 10 highest production blocks. The experimental period was from day 22 to 120 postpartum. Lysine supplementation resulted in an optimal dietary lysine : methionine ratio in metabolisable protein of 7.2 : 2.4. Lysine supplementation did not affect dry matter intake, milk production, milk fat percentage, milk protein percentage, milk urea nitrogen, body weight or body condition score; but decreased the non-casein nitrogen and whey content of milk. Furthermore, milk casein, which is the milk nitrogen fraction most sensitive towards increased duodenal supply of lysine and methionine, was not affected. The rumen protected lysine product evaluated did not improve cow productivity, probably because the product was either unprotected from rumen degradation, or overprotected to the extent that the lysine was not available for absorption in the small intestine; or absorbed but could not be metabolised. Copyright / Dissertation (MSc(Agric))--University of Pretoria, 2009. / Animal and Wildlife Sciences / unrestricted

Virginiamycin (V) and Ionophores, such as Poulcox (active ingredient monensin sodium), are antimicrobial feed additives approved for use in cattle to improve performance. The effect of virginiamycin on Gram positive bacteria is similar to that of monensin (M) although the modes of actions differ. Very little information is available on the potential synergistic effects of V and M, especially in dairy cattle diets. The objectives of this study were to investigate the effect of combinations of V and M on the performance of dairy cows. Forty high producing Holstein cows were blocked according to previous milk production and randomly allocated to one of the following lucerne based total mixed diets: 1) Control, no medication (C); 2) Control plus 20 ppm virginiamycin (V); 3) Control plus 15 ppm monensin (M); 4) Control plus 20 ppm virginiamycin and 15 ppm monensin (V+M). The experimental period was from 21 days prepartum until 60 days postpartum. Data were analysed according to a randomized block design, using the model GLM procedure (SAS, 2001). Dry matter intake varied from 23.6 kg/d to 25.4 kg/d and did not differ between treatments (P>0.10). Milk production was higher (P<0.10) for cows receiving V+M (41.2 kg/d) when compared to cows receiving only V (36.6 kg/d), but did not differ from other treatments (P>0.10). Milk fat % was lower for cows receiving M (3.42 %) and the control (3.62 %) when compared to treatment V+M (3.86 %) (P<0.10). Milk protein and MUN did not differ. Body weight loss for the period from calving until day 60 postpartum, tended (P<0.15) to be less for cows receiving V+M (-8.1 kg) when compared to the control (-34.2 kg) and M (-31.9 kg) treatments. Both treatments M and V respectively, decreased blood BHBA and treatment M increased blood glucose (P<0.10) when compared to the control diet. Results suggest a complementary effect between the two additives monensin and virginiamycin when supplemented to early lactation cows. / Dissertation (MSc(Agric))--University of Pretoria, 2008. / Animal and Wildlife Sciences / unrestricted

No description available.

Manure nitrogen in dairy cattle represents a substantial economic and environmental loss to the industry. Current strategies used to improve N efficiency (Neff) have shown limited progress and thus, warrant more effective approaches. Considering that the gastrointestinal bacterial community has been associated with various phenotypes of economic importance, the objective of this project was to evaluate the associations between the rumen and fecal bacteriomes and Neff phenotypes in dairy cows. Results showed similarities in the overall bacterial community composition and structure of cows differing in Neff. However, the relative abundance of specific bacterial ASV differed between low and high Neff cows. Furthermore, bacterial ASV strongly correlated with Neff could be involved in processes such as nutrient supply, performance, and feed efficiency. These suggest that the gastrointestinal bacterial community is a factor influencing Neff in dairy cows and specific bacterial members can potentially serve as markers of Neff phenotypes.