Licentiatavhandling (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2008. / Härtill 2 uppsatser. I boken felaktigt tryckår 2006.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2009. / Härtill 4 uppsatser.

Studies in various animal species have demonstrated that stress during pregnancy can have a detrimental effect on progeny health and development throughout its postnatal life. If this were to apply to dairy cows, minimising stress in pregnant cows could be of critical importance in ensuring offspring health and welfare. However, relationships between maternal health and welfare and offspring performance have not been well investigated in dairy cattle. Traditionally management strategies for cows in late pregnancy (i.e. in the dry period) have focused on maximising milk production whilst minimising impacts on postpartum health. This may include management practices that can have a negative impact on the health and welfare of cows in the dry period itself. This project aimed to identify potential sources of stress associated with management practices in late pregnant cows, and to investigate its effects on offspring health, behaviour and welfare. A survey was conducted to investigate typical dry cow and pre-weaned calf management practices on dairy farms in the United Kingdom (UK). Data from 148 commercial UK dairy farms provided valuable information on dry cow and pre-weaning calf management. Procedures that were commonly practised but potentially stressful for dry cows included the abrupt cessation of milking and frequent changes in diet and social environment. Two experimental studies were conducted to investigate the impact of alternative management practices in late pregnancy on progeny welfare. The first experiment investigated the behavioural, physiological and metabolic responses of dry cows to industry minimum standards (H: high stocking group) compared to a more extensive space allowance (L: low stocking density). The offspring of these cows were monitored until weaning to assess their responses to typical dairy farm procedures. The second experiment was conducted on calves born to heifers from an out-wintering project. Pregnant heifers were kept either indoor or outdoor grazing (on deferred grass or kale) throughout the winter period. The health, growth and behaviour of offspring were monitored for the first 14 days of life. Limited feed-face space resulted in altered feeding patterns and increased competition at the feed-face. There was no association between dry period stocking density and the physiology and metabolism of dry cows. Maternal treatment had no impact on pre-weaned calf birth weight, health, growth, passive immunity, neonatal vigour and the majority of behavioural outcomes. However, H calves made more frequent social contact with companions compared to L calves and showed higher behavioural reactivity to weaning. Maternal high stocking density treatment and previous disease incidence in calves reduced the behavioural reactions to disbudding and the expression of pain-related behaviours. Out-wintering of pregnant heifers on kale showed no negative impact on growth compared to the indoor group, whilst out-wintering on deferred grass resulted in the lowest growth rate. However, out-wintering on deferred grass may have enhanced offspring social motivation and learning ability. This study has demonstrated potential associations between maternal experience during pregnancy, and offspring growth and behaviour. The effect of maternal treatment on offspring behaviour may be more likely to emerge in challenging situations. Further research will be needed to understand the underlying mechanisms and to reach definite conclusions, which would have implications for improving the welfare of late pregnant cows and their offspring.

Orientador: José Luiz Moraes Vasconcelos / Resumo: 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... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: 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) / Mestre

Rumen-undegradable protein might be the first limiting nutrient for high producing dairy cows receiving high levels of maize supplementation while grazing pasture. To test this hypothesis two trials were conducted using fishmeal as a high quality protein source rich in rumen-undegradable protein, Methionine and Lysine. In the first trial cows grazed annual ryegrass for two months in spring. In the second trial cows grazed kikuyu for two months in late summer. In addition to the pasture cows received 6 kg (as is) of a maize-based supplement, including minerals, fed in two equal portions in the milking parlour. A randomised complete block design was used. Three groups of 15 (ryegrass) or 14 (kikuyu trial) cows received control (no fishmeal), low fishmeal (4 % fishmeal replacing maize) or high fishmeal (8 % fishmeal replacing maize) treatments. Multiparous, high producing, Jersey cows in early to mid lactation were used. Milk production was measured and milk samples taken fortnightly. Simultaneous studies were conducted using eight rumen cannulated cows receiving the control and high fishmeal treatments in a cross over design experiment. Ruminal pH, ammonia-N and volatile fatty acid concentrations were measured. In the ryegrass trial milk yield, 4 % fat-corrected milk yield and milk fat and protein percentages of cows on the low and high fishmeal treatments (21.9 and 22.1 kg milk/d, 24.1 and 24.2 kg 4 % fat-corrected milk/d, 4.73 and 4.67 % fat and 3.49 and 3.45 % protein) were significantly higher than the control (20.5 kg milk/d, 20.4 kg 4 % fat-corrected milk/d, 3.97 % fat and 3.25 % protein). There was no treatment effect on milk urea N (16.8, 17.4 and 17.9 mg/dl, for the control, low fishmeal and high fishmeal treatments, respectively). The ruminal ammonia-N concentration was significantly higher in the cows on the high fishmeal treatment than the control (16.67 vs. 14.16 mg/dl). Fishmeal supplementation to cows on ryegrass is profitable under any realistic price scenarios in South Africa. In the kikuyu trial cows on the high fishmeal treatment produced significantly more milk (19.5 kg/d) than the cows on the control (18.2 kg/d), neither differing from the low fishmeal treatment (18.9 kg/d). The cows on the low fishmeal treatment had significantly higher milk fat percentage (4.18 %) than the control (3.71 %), neither differing from the high fishmeal treatment (3.91 %). The cows on the two fishmeal treatments produced significantly more 4 % fat-corrected milk than the control (19.4 and 19.2 vs. 17.3 kg 4 % fat-corrected milk/d). There was no treatment effect on milk protein percentage (3.30, 3.41 and 3.34 % for the control, low and high fishmeal treatments, respectively). Milk urea N was significantly higher for the high fishmeal treatment (10.80 mg/dl) than the control and low fishmeal treatments (9.09 and 9.44 mg/dl). Ruminal ammonia-N concentration was significantly higher in the cows on the high fishmeal treatment than the control (6.52 vs. 4.74 mg/dl). Fishmeal supplementation to cows on kikuyu could be profitable under certain price scenarios. / Dissertation (MSc(Agric) (Animal Science))--University of Pretoria, 2008. / Animal and Wildlife Sciences / unrestricted

The widespread increase in use of maize-based feedstuffs in California dairy cow rations has raised concerns of reduced efficiency of CP utilization due to the low lysine content of maize and maize by-products. The objectives of this research were to determine the impact of increased dietary maize CP levels on animal performance using three metabolic models of dairy cows in order to predict limiting AA’s in California dairy rations to identify a ruminally protected AA package to supplement similar rations. Since lysine was the most consistently predicted limiting AA among dairies, and metabolic models, the dairy with the ration calculated to be the most limiting in lysine was chosen to determine effects of feeding an RPL product on milk production and composition, as well as on N balance. Nutrient profiles of 16 high multiparity cow rations were evaluated and limiting AA predicted by the metabolic models Amino Cow, CPM Dairy and Shield. Higher inclusion levels of maize products in rations increased the contribution of maize CP to the total CP content of the TMR, to between 20 – 40%, but had no impact on cow performance. Even though the lysine to methionine ratio decreased as more maize CP was included in the TMR, it did not have a major impact on the final predicted AA profile of MP, or milk component levels, but, according to Shield, it had an effect on milk yield. Methionine, isoleucine and lysine were predicted to be most limiting according to Amino Cow, CPM Dairy and Shield respectively. The models suggested three dramatically different AA packages but the high degree of consistency within model in predicting the limiting AA sequence among dairies, suggest that there may be sufficient consistency in the nutrient profiles among rations to support production of a ruminally protected AA complex. The second experiment used a double (i.e., early and mid-lactation multiparity dairy cows) 2 x 2 factorial with 28 day experimental periods. Feeding the RPL, with estimated rumen escape of lysine between 18 and 23% suggesting an increased intestinal absorption of lysine between 8 and 22 g/d/cow, did not influence DMI or milk, true protein and lactose yields. Milk fat yield and concentration decreased, while MUN percentages increased when RPL was fed. Blood plasma levels of almost all AA’s, except lysine, decreased when RPL was fed, suggesting that lysine was the limiting AA and that its supplementation led to increased absorption and utilization of other AA. The lack of response in milk protein synthesis and the decrease in plasma 3-MH concentrations when RPL was fed suggests that muscle protein synthesis was stimulated, and degradation reduced, with RPL feeding. It is possible that lysine had an effect, either directly or indirectly, on muscle protein turnover and energy metabolism that, impacted intakes, metabolism and absorption of AA and milk production in mid lactation cows, but it had no major impact on early lactation cows. Copyright / Dissertation (MSc(Agric))--University of Pretoria, 2009. / Animal and Wildlife Sciences / unrestricted

Rumen protected methionine has been used in an effort to improve the amino acid composition of metabolisable protein since the early 1960’s. The positive response in dairy cows in terms of milk protein composition and milk production, especially during early lactation has been well documented. Rumen protected methionine supplementation contributes to improving the protein efficiency of the dairy cow which improves the overall productivity of the dairy enterprise. Recently a locally developed liquid rumen protected methionine prototype became available. In our study this product was evaluated through a series of experiments in conjunction with two standard, well known methionnine sources, Smartamine ™ M and unprotected DL-methionine that provided a reference to the relative bioavailability of the liquid rumen protected methionine. In the first of the two studies the effect of methionine supplementation on milk yield, milk composition as well as milk protein composition was evaluated through the milk composition technique. The ability of the liquid rumen protected methionine to elevate blood plasma methionine levels was also evaluated through the blood plasma technique after oral dosing and post ruminal infusion of methionine. The liquid rumen protected methionine prototype induced no response in either milk yield or milk composition. Results suggested that the prototype is either not adequately protected against rumen degradation or it is not available for absorption in the small intestine. The inability of the liquid rumen protected methionine prototype to elevate blood plasma methionine after post ruminal infusion further proved that the product is not available for absorption at this site either. In the event that the product’s mode of action or method of protection caused it not to be detected as pure methionine in the blood, an effect on milk yield would have been expected which was not the case. This product proved to have a very low or no bioavailability in comparison to the well researched and proven Smartamine ™ M. / Dissertation (MSc(Agric))--University of Pretoria, 2012. / Animal and Wildlife Sciences / unrestricted

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The subject of my thesis was an analysis that deals with the level of nutrition of holstein cattle, witch evaluates feeding, drinking, silage quality techniques and optimalization of the feed ration in 2017 and 2018. In 2017 the feed ration used for dairy cows contained more PDIE. In 2018 the feed ration contained lower amount of energy (6MJ NEL/ 1kg of dry matter) and NL (138,6 g NL/kg of dry matter). After comparing of these two diets for dairy cows with nutrient need, there was recommended an increase of dry matter content in feeding ration. In the milk productivity assessement, the fat and protein content, SC, total aerobic microbial count, was reviewed. The statistic shows the impact of the season of the year on the fat and protein content, SC, total aerobic microbial count in milk. From ecomomy point of view, costs per litre of selled milk was 7,69 Kč in 2017, which was lowered to 7,28 CZK per litre of selled milk. Both years was profitable, and in comparing the economy from 2017 with Czech republic average, tracked stable was more profitable 3 662 CZK per dairy cow.