Foram realizados três experimentos visando avaliar diferentes estratégias de vedação. No experimento I, objetivou-se avaliar as características fermentativas e a estabilidade aeróbia das silagens de milho vedadas com diferentes tipos de filme plástico, aplicação na camada superior de aditivo químico ou microbiano e proteção do filme com terra, visando o controle da deterioração aeróbia. Houve diferença para o tipo de filme plástico utilizado, onde foi observado maiores valores de temperatura para as silagens vedadas com o filme de polietileno. As silagens aditivadas com benzoato de sódio ou Lactobacillus buchneri apresentaram menores perdas de matéria seca e menores valores de pH com relação a silagem não aditivada. Apenas em três amostras foram detectadas a presença de aflatoxina B1. No experimento II, objetivou-se avaliar estratégias de vedação, com base na proteção do filme plástico, visando o controle da deterioração aeróbia nas zonas periféricas do silo e o comportamento dessas silagens durante o período de aerobiose. No momento da abertura dos silos a contagem de leveduras foi maior para a silagem que não teve proteção sobre o filme plástico. A digestibilidade verdadeira in vitro da matéria seca apresentou diferença, sendo que as silagens que receberam proteção sobre a lona apresentaram os maiores valores em relação a silagem sem proteção sobre o filme plástico. No experimento III, objetivou-se avaliar diferentes tipos de filmes plásticos na vedação de silos horizontais e suas interferências relativas a qualidade das silagens, ao desempenho de vacas em lactação e qualidade do leite produzido. As maiores quantidades de silagem descartada foram para os tratamentos com a lona preta e lona dupla face. As maiores taxas de permeabilidade da lona ao oxigênio foram observadas para os filmes dupla face e preto de material virgem. A dieta que continha silagem proveniente do silo vedado com lona preta de material reciclado com proteção de bagaço apresentou o maior valor para a produção de leite, sendo a menor média verificada para o tratamento que continha filme plástico preto de material virgem. Ao longo das semanas de experimentação foi verificada a presença de aflatoxina B1 em todas as silagens. A partir do mês de agosto foi verificada positividade para aflatoxina M1 entre as amostras de leite. A dieta que continha silagem proveniente do silo vedado com lona preta de material reciclado e proteção de bagaço apresentou o maior valor de digestibilidade, tanto da matéria seca como da matéria orgânica das dietas. O polímero de poliamida, a proteção da lona com terra ou bagaço e o uso de aditivos como Lactobacillus buchneri ou benzoato de sódio reduzem a deterioração aeróbia de silagens de milho. A proteção da silagem contra o aquecimento, pelo uso da poliamida ou da proteção com bagaço, auxilia na obtenção de silagem de melhor qualidade e facilita o manejo pela redução da mão-de-obra no descarte de silagem deteriorada. O desempenho animal é afetado pela estratégia de vedação utilizada, podendo até mesmo afetar qualidade higiênica do leite produzido. / Three experiments were conducted to evaluate different strategies to cover the silo. The experiment I evaluate the fermentation profile and aerobic stability of com silage covered with different types of plastic sheets, applying additives in the top layer and, protecting the fi 1m with soil, to reduce the top losses in com silages. Higher temperature values were observed for the com silage covered with the polyethylene film. The use of additives showed lower DM losses and pH values in relation the control silage. The presence of aflatoxin 81 was detected in three samples only for the silage covered with polyethylene film, without additive and without soillayer over the top of the film. The experiment 11 was designed to study the effectiveness of covering methods to reduce the top losses in maize silages. The. yeast count was higher for control silage. The dry matter digestibility showed higher values for the protected silos in relation to unprotected treatment. The experiment 111 was designed to evaluate different plastic sheets to seal horizontal silos and their influence on the silage quality, Holstein dairy cows performance and milk quality. There was no difference between treatments for the fermentation profile. The silages temperature values in the silo top and top side increased in relation to samples in the panel center. The deteriorated discarded silage showed high values in silages covered with black virgin polyethylene and black-on-with polyethylene films. Those plastics films showed the highest rates of oxygen permeability. The diet containing silage from black recycled polyethylene with bagasse protection showed the highest value for milk yield, while the lowest milk yield was found to the black virgin polyethylene treatment. Over the experimentation period, the presence of aflatoxin 81 in silage was observed. The diet containing silage from black recycled film protect with bagasse treatment showed the highest digestibility of both dry matter and organic matter. The polyamide plastic film, the use of soil or sugarcane bagasse as a plastic film protection and, application of additives on the silo upper layer, reduce the com silage aerobic deterioration. Inhibiting the silage warming by using polyamide plastic film or sugarcane bagasse, helps in obtaining better quality silage management, reducing the costs and labor associated with the discarded silage. Animal performance is affected by the strategy used to seal the silage and may even affect hygienic quality of milk

O rebanho brasileiro de bovinos leiteiros é composto predominantemente por vacas mestiças criadas em condições tropicais. Os principais modelos usados no Brasil para a formulação e avaliação de dietas são norte-americanos e baseados nas exigências de vacas Holandesas em clima temperado. A principal contribuição do primeiro capítulo deste estudo foi o desenvolvimento e avaliação de um novo modelo para estimar a ingestão de matéria seca (IMS) de vacas mestiças. A nova equação de predição da IMS foi desenvolvida e avaliada usando um banco de dados com 161 médias de tratamentos provenientes de 38 estudos brasileiros publicados com vacas mestiças [n = 446 vacas, 16,60 ± 5,70 (DP) kg leite/dia]. O modelo proposto foi: IMS (kg/dia): [0,5552 (± 0,06636 EP) × LC4%G + 0,06332 (± 0,009455) × PV0,75] × [1 - e (- 0,7732 (± 0,7019) × (SEM - 1,629 (± 1,9313))) ]. O novo modelo apresentou maior acurácia (QMEP = 1,64, r2 = 0,88) na predição da IMS quando comparado com modelos norte-americanos. O novo modelo de predição da IMS pode ser aplicado na formulação de dietas para vacas leiteiras mestiças em condições tropicais. No capítulo 2, um estudo avaliou as novas atualizações das exigências nutricionais de bezerras leiteiras sugeridas por Van Amburgh e Drackley (2005) e inseridas em programa comercial (AMTS, Agricultural Modeling and Training Systems, AMTS.Cattle.ProTM Calf Model versão 3.5.8.0, 2015). Dados de 16 estudos brasileiros envolvendo 51 dietas para bezerros leiteiros (n = 485, peso ao desmane de 62,02 ± 10,16 kg) foram usados para avaliar os modelos do NRC (2001) e o AMTS. Nas condições do conjunto de dados do presente estudo, ambos os sistemas superestimaram o ganho calculado a partir da proteína disponível. O ganho de peso estimado pela energia disponível da dieta, foi superestimado em 19 g/dia quando calculado pelo NRC e subestimado em 68 g/dia quando calculado pelo AMTS. O ganho de peso possível a partir da energia disponível foi menor quando calculado pelo AMTS em relação ao NRC (2001). Para o conjunto de dados experimentais brasileiros, os ganhos de peso de bezerros foram 32% inferiores aos descritos na literatura para sistemas norte-americanos. As razões para esta discrepância precisam ser compreendidas, pois somente assim novos modelos poderão ser desenvolvidos e parametrizados para estimar o desempenho animal de forma mais acurada e precisa. / The Brazilian dairy herd is mainly made up of crossbred cows fed under tropical conditions. The main models in use to formulate and evaluate diets in Brazil are from North America. These models are based on the requirements of Holstein dairy cows under temperate climate. Therefore, the main contribution of this first Chapter was the development and evaluation of a new model to estimate dry matter intake (DMI) of crossbred dairy cows. The new DMI equation was developed and evaluated using a database with 161 treatment means from 38 published studies of Brazilian crossbred cows [n = 446 dairy cows, mean milk production of 16.60 ± 5.70 (SD) kg/day]. The new model showed higher DMI prediction accuracy (MSEP = 1.64, r2 = 0.88) than American models. Therefore, this model can be used in the formulation of diets for crossbred dairy cows under tropical conditions. In Chapter 2, we evaluated the updates on the nutritional requirements of dairy calves suggested by Van Amburgh and Drackley (2005) and inputted into Agricultural Modeling and Training Systems (AMTS, AMTS.Cattle.ProTM Calf Model version 3.5.8.0, 2015). Data from 16 previous Brazilian studies involving 51 diets for dairy calves (n = 485 calves, weaning weight of 62.02 ± 10.16 kg) were used to evaluate the Nutrient Requirements of Dairy Cattle - NRC (2001) and AMTS models. According to the data set from this study, both systems overestimated the gain calculated from the available protein. The weight gain estimated by the energy available from the diet was overestimated by 19 g/day when calculated by the NRC and underestimated by 68 g/day when calculated by AMTS. Weight gain estimated by the dietary energy of the AMTS system was lower than the NRC (2001). The Brazilian data set showed a calf gain around 32% lower than those described in U.S. dairy farms. The reasons for this discrepancy need to be understood, for only then can new models be developed and parameterized to estimate animal performance more accurately and precisely.

O objetivo deste estudo foi verificar a ocorrência de S. aureus e E. coli O157: H7 no leite de vacas com mastite subclínica e no leite de mistura de 42 propriedades leiteiras localizadas em duas regiões do Estado de São Paulo: São Carlos e Ribeirão Preto. Paralelamente, entre os isolados de S. aureus foi objetivo identificar os produtores de toxinas e determinar sua origem epidemiológica. O isolamento de S. aureus foi realizado em agar Baird-Parker (35ºC, 48h) e a confirmação bioquímica através da catalase, coagulase, termonuclease, produção de acetoína e fermentação aeróbia da maltose. O isolamento de E. coli O157: H7 foi realizado em agar Sorbitol MacConkey MUG (35ºC, 24h). Para confirmação utilizaram-se as provas do IMVC e sorologia através do kit Soro Anti E. coli O157. Para a detecção da TSST-1 e das enterotoxinas A, B, C e D utilizou-se aglutinação reversa passiva em látex (RPLA). A identificação epidemiológica dos isolados de S. aureus foi realizada por eletroforese em gel de campo pulsado (PFGE). A ocorrência de S. aureus no leite individual nas regiões 1 (São Carlos) e 2 (Ribeirão Preto) foram 3,9% e 6,7%, respectivamente. Animais pertencentes às propriedades leiteiras com produção entre 400 L e 1.000 L/dia apresentaram maior risco de veiculação de S. aureus através do leite quando comparadas com propriedades com produção 1.000 L/dia. Quanto ao leite de mistura, verificou-se que a ocorrência de S. aureus foi a mesma em ambas as regiões (19%). A produção simultânea das enterotoxinas B e C foi observada em 4,7% dos isolados de leite individual, enquanto que 4,7% produziram enterotoxina A e toxina TSST-1. A produção de TSST-1, isoladamente, foi constatada em 14,3% dos isolados de leite individual e em 25% do leite de mistura. Houve similaridade genética entre os isolados de S. aureus, evidenciando sua dispersão epidemiológica entre as propriedades avaliadas. A ocorrência de E. coli O157: H7 no leite individual foi 1% na região 1 e 1,6% na região 2. No leite de mistura não foi detectada E. coli O157: H7. Ressalte-se a importância de medidas preventivas para assegurar a qualidade do leite durante a ordenha, a fim de evitar a ocorrência de microrganismos patogênicos, principalmente S. aureus, e conseqüentemente prevenir riscos de veiculação de toxinfecções através deste alimento. / The aim of this study was to verify the occurrence of S. aureus and E. coli O157: H7 in the milk from dairy cows with subclinical mastitis and in the bulk milk from 42 dairy farms located in two regions of São Paulo State (Region 1: São Carlos, Region 2: Ribeirão Preto). Among the S. aureus strains isolated, the aim was to identify the toxin producers and their epidemiological origin. The isolation of S. aureus was conducted using Baird-Parker agar, and the strains were confirmed by catalase, coagulase, thermonuclease, maltose aerobic fermentation and acetoin production. The isolation of E. coli O157: H7 was conducted using Sorbitol MacConkey MUG agar. The strains were confirmed by IMVC and serology using anti E. coli O157 sera. Rapid passive latex agglutination was used for detection of TSST-1 and enterotoxigenic strains of S. aureus. The epidemiological identification was performed using pulsed field gel electrophoresis (PFGE). S. aureus was isolated from 3.9% and 6.7% of the individual milk samples from regions 1 and 2, respectively. Dairy cows belonging to farms with milk production ranging from 400 to 1.000 L/day showed higher risk of S. aureus carrying-over, when compared with dairy farms with milk production < 400 L/day and > 1.000 L/day. In bulk milk samples, the occurrence of S. aureus was the same in both regions evaluated (19%). The simultaneous production of enterotoxin B and C was observed in 4.7% of strains isolated from individual milk samples, while 4.7% produced both enterotoxin A and TSST-1. TSST-1 production alone was observed in 14.3% of S. aureus strains isolated from individual milk and 25% of bulk milk samples. S. aureus strains tested by PFGE demonstrated genetic similarity, showing the dispersion patterns of this microorganism among dairy farms. E. coli O157: H7 was isolated from 1% and 1.6% of individual milk samples from regions 1 and 2, respectively, although it was not detected in bulk milk samples. The importance of preventive measures to ensure milk quality during milking extraction is stressed, aiming to avoid pathogenic agents, mainly S. aureus, and therefore, to prevent the carry-over of food borne diseases to humans through milk.

O mundo atual passa por uma revolução na produção industrial de animais, busca-se atender as exigências do mercado focando na qualidade do produto final e nos sistemas de produção. A partir da preocupação pública com a melhoria do bemestar de animais de produção e o maior controle da cadeia produtiva, protocolos internacionais com recomendações de boas práticas de produção foram desenvolvidos, a fim de simplificar e esclarecer os princípios de bem-estar animal (BEA) para o setor produtivo. No Brasil, os sistemas existentes e as pesquisas direcionadas ainda estão na fase de avaliar os gargalos tecnológicos, oriundos de sistemas de produção com diferenças em relação às escalas de produção. Nesse contexto, há a necessidade de avaliar cada sistema brasileiro de produção, suas particularidades e comparar aos sistemas europeus e americanos. O Brasil é um país de destaque na produção de proteína animal, e deve estabelecer suas próprias condições de qualidade frente à sua escala e a suas particularidades de produção. Não há como simplesmente aderir às exigências internacionais, sem atentar para a realidade nacional seja ela de produção, de nível tecnológico e de exigências/dificuldades dos produtores rurais. Baseando-se na necessidade do estabelecimento de padrões para o sistema brasileiro de produção de leite em pasto, conforme Instrução Normativa 56/2008, do Ministério da Agricultura Pecuária e Abastecimento (MAPA), esse estudo propôs uma adaptação do sistema de avaliação do protocolo Welfare Quality® Assessment protocol for cattle - applied to dairy cows (2009) para avaliação do bem-estar de vacas leiteiras em sistema de pastejo. A aplicação do protocolo Welfare Quality adaptado para o sistema de pastejo possibilitou a avaliação e a classificação de forma quantitativa e qualitativa em relação ao bem-estar geral do rebanho, e consequentemente da propriedade leiteira. / The current world is going through a revolution in the industrial livestock production, so it is important to meet market demands by focusing on product quality and farming systems. Based on public concern regarding farm animal welfare improvement and greater control of the productive chain, international protocols with good production practices recommendations were developed in order to simplify and clarify animal welfare principles to the productive sector. In Brazil, the existing systems and targeted researches are still at the stage of assessing technologic bottlenecks, arising from production systems with differences related to production scales. In this context, there is a need to assess each Brazilian production system, their peculiarities and to compare European and American systems. Brazil is a country of prominence in animal protein production and shall establish its own quality conditions ahead of its scale and its production particularities. There is no simply meeting international requirements without considering the national reality of production, technological level and farmers\' demands/difficulties. Relying on the need to establish standards for Brazilian system of milk production in pasture, according to Normative Instruction n° 56/2008, from the Ministry of Agriculture, Livestock and Supply (MAPA), the present paper proposed an adapted evaluation system from Welfare Quality Protocol® -Assessment protocol for cattle - applied to dairy cows (2009) to assess the welfare of dairy cows raised in pasture. The implementation of the WQ adapted protocol allowed the evaluation and classification of the farms quantitative and qualitatively in relation to general animal welfare, and consequently the production facility.

A nutrição está intimamente relacionada com a reprodução nos animais e ainda há muito a se estudar sobre essa inter-relação, principalmente porque ainda há muita controvérsia na literatura sobre este tema. Por exemplo, alguns estudos sugerem ser benéfico o uso do \"flushing\" nutricional na produção de embriões em ruminantes. Entretanto, a maioria dos trabalhos mostra resultados negativos da alta ingestão de matéria seca (IMS). Dessa forma, existe a necessidade em se avançar nos estudos comparando a fisiologia reprodutiva e produção de embriões em fêmeas sob diferentes níveis nutricionais. Foram utilizadas 33 vacas Nelores não lactantes recebendo um dos quatro tratamentos a seguir: Os grupos Mantença (M), Restrição (0,7M) e Alta IMS (1,5M) receberam a mesma dieta padrão variando a quantidade oferecida. O grupo Alta ingestão de energia (E), recebeu uma dieta com alto teor de amido, com a mesma energia do grupo 1,5M, porém, com a mesma IMS do grupo M. Todas as vacas passaram por todos os tratamentos, em um modelo crossover. Estes animais tiveram o ciclo estral sincronizado e acompanhamento ovariano diário, por meio de ultrassonografia até confirmação da ovulação. Posteriormente, nos dias 7 e 10 do ciclo estral foi avaliado o volume do corpo lúteo (CL). Concentrações circulantes de hormônios esteróides (progesterona [P4] e estradiol [E2]) foram mensuradas em dias estratégicos. Os animais foram submetidos à aspiração intrafolicular (OPU) por volta do dia 12 do ciclo estral e dois dias após a OPU, os animais foram superestimulados e avaliou-se a resposta superovulatória e a qualidade embrionária entre os grupos, assim como a taxa de prenhez de 273 receptoras após transferência em tempo fixo dos embriões vitrificados. As análises foram realizadas de acordo com o Proc GLIMMIX do SAS, com nível de significância de P < 0,05. Os resultados estão apresentados na forma de média dos quadrados mínimos ± erro padrão. Este estudo englobou duas áreas principais: fisiologia e concentrações hormonais (Experimento 1) e produção in vivo de embriões (Experimento 2). Apesar de, no Experimento 1, terem sido avaliadas 33 vacas nas quatro repetições, totalizando 132 sincronizações, houve apenas 75 ovulações, as quais foram consideradas para as análises subsequentes. A taxa de ovulação não variou entre os tratamentos (~57%). O folículo ovulatório foi maior conforme a IMS aumentou para a dieta padrão nos grupos 1,5M, M, 0,7M (14,4 ± 0,3a vs 12,8 ± 0,3b vs 12,0 ± 0,3c nos grupos 1,5M, M e 0,7M, respectivamente). Apesar disso, o E2 circulante não diferiu entre os grupos. O volume do CL no Dia 7 do ciclo estral foi semelhante entre os grupos, todavia o grupo 1,5M apresentou menor concentração de P4 circulante (2,4 ± 0,2 ng/mL) em relação aos grupos M e 0,7M (2,9 ± 0,2 vs 3,0 ± 0,3 ng/mL, respectivamente). No Experimento 2, a concentração de insulina plasmática foi maior no grupo E (8,7 ± 0,86 ?UI/mL) comparado com os grupos 0,7M (4,6 ± 0,87) e M (5,3 ± 0,85), não diferindo do grupo 1,5M (6,6 ± 0,9). Houve maior resposta superovulatória (CL) nas doadoras que receberam a dieta padrão, 0,7M (13,0 ± 1,3a); M (14,2 ± 1,2ª) e 1,5M (13,9 ± 1,2ª) comparado às alimentadas com alta energia (9,7 ± 1,2b), devido à correlação negativa entre resposta superovulatória e insulina (r = -0,32). Apesar disso, não houve diferença entre os grupos para o número total de ovócitos/embriões colhidos (~6 estruturas), embriões viáveis (~3 embriões), ou congeláveis (~2,7 embriões). Independente de tratamento, a insulina circulante ao início da superovulação, apresentou correlação negativa com o número de embriões viáveis (r = -0,22). A prenhez aos 23 e 53 dias após a transferência dos embriões não diferiu entre os tratamentos, entretanto, a insulina circulante das doadoras teve correlação negativa com a prenhez das receptoras aos 60 dias de gestação (r = -0,16). Em conclusão, diferentes níveis de IMS alteraram o tamanho das estruturas ovarianas e/ou as concentrações circulantes de hormônios esteróides. Apesar disso, houve um efeito muito discreto de dieta na resposta superovulatória e qualidade embrionária das vacas. Independente de tratamento, alta insulina circulante das doadoras foi associada a menor resposta superovulatória, número de embriões viáveis e prenhez das receptoras aos 60 dias de gestação. / Nutrition is closely related to reproduction and there is still much to learn about this relationship, mainly because there is so much controversy in the literature on this topic. For example, some studies propose beneficial use of nutritional \"flushing\" on embryo production in ruminants. However, most studies show negative results of high dry matter intake (DMI). Thus, there is a need to advance in studies comparing reproductive physiology and embryo production in females under different nutritional levels. A total of 33 non-lactating Nelore cows received one of the following treatments: Groups maintenance (M), Restriction (0.7M) and High DMI (1.5M) received the same standard diet with variations in the amount offered. The group High intake of energy (E) received a diet with high starch content, but the same amount of energy as group 1.5M, however, with the same DMI as Group M. All cows underwent all treatments in a crossover model. These animals had their estrus synchronized and ovarian dynamics was monitored daily by ultrasound until confirmation of ovulation. Subsequently, on days 7 and 10 of the estrous cycle the volume of the corpus luteum (CL) was estimated. Circulating concentrations of steroid hormones (progesterone [P4] and estradiol [E2]) were measured in strategic days. The cows underwent intrafollicular aspiration (OPU) on day 12 of the estrous cycle, and two days after OPU, the cows ovaries were supererstimulated. The superovulatory response and embryo quality was compared among groups, as well as pregnancy rate of 273 recipients after receiving fixed-time transfer of vitrified embryos. Analyses were performed according to the Proc GLIMMIX of SAS, with a significance level of P < 0.05. Results are presented as least squares means ± standard error. This study included two main areas: physiology and hormone concentrations (Experiment 1) and in vivo embryo production and pregnancy rate (Experiment 2). Although, in Experiment 1, 33 cows were evaluated in four repetitions, totaling 132 synchronizations, there were only 75 ovulations, which were considered for subsequent analyzes. The ovulation rate did not vary between treatments (~57%). The size of the ovulatory follicle incresed as the DMI of the standard diet increased (14.4 ± 0.3a vs 12.8 ± 0.3b vs 12.0 ± 0.3c for groups 1.5 M, M and 0.7M, respectively). Nevertheless, the circulating E2 did not differ between groups. The volume of the CL on Day 7 of the estrous cycle increased as the DMI of the standard diet increased, but the 1.5M group had lower circulating concentrations of P4 (2.4 ± 0.2 ng/mL) than groups M and 0.7M (2.9 ± 0.2 and 3.0 ± 0.3 ng/mL, respectively). In Experiment 2, plasma insulin concentration was higher in the E group (8.7 ± 0.86 ?IU/mL) compared with groups 0.7 M (4.6 ± 0.87) and M (5.3 ± 0.85) not differing from group 1.5M (6.6 ± 0.9). There was a higher superovulatory response (CL) in donors receiving the standard diet [0.7M (13.0 ± 1.3), M (14.2 ± 1.2) and 1.5M (13.9 ± 1.2)] compared with those fed high energy (9.7 ± 1.2 CL) due to the negative correlation between superovulatory response and circulating insulin (r = - 0.32). Nevertheless, there was no difference between groups for the total number of oocytes/embryos collected (~6 structures), viable embryos (~3 embryos), or freezable (~2.7 embryos). Regardless of treatment, circulating insulin at the beginning of superovulation, was negatively correlated with the number of viable embryos (r = -0.22). Pregnancies at 23 and 53 days after embryo transfer did not differ between treatments, however, circulating insulin of the donor cows had a negative correlation with pregnancy of recipients at 60 days of gestation (r = -0.16). In conclusion, different levels of DMI changed the size of ovarian structures and/or the concentrations of circulating steroid hormones. Nevertheless, there was a very minor effect of diet on superovulatory response and embryo quality in cows. Regardless of treatment, high circulating insulin of the donors was associated with lower superovulatory response, lower number of viable embryos and less pregnancies of recipients at 60 days of gestation.

The aim of this study was to evaluate the effects of M. elsdenii (Me) dosing on dairy heifer performance. A secondary set of data (feed intake, heifers birth weights, age and Weight at insemination, and first lactation milk performance) of heifers (dosed and not dosed with Me) was obtained from the dairy herd of the Agricultural Research Council – Animal Production. Data were arranged in a complete randomised design and analysed as repeated measures. Milk, pre-weaning starter and metabolised energy intake did not differ between the control and the Me groups. Post-weaning starter feed intake was higher (p=0.03) for Me fed heifers than control heifers. The post-weaning metabolisable energy intake was also higher (p=0.03) for heifer fed Me than control heifers. The average daily weight gain of heifers dosed with Me was higher during the pre-weaning period (0.66 kg/day; p=0.04) and after weaning (1.12 kg/day; p=0.03) compared to control (0.60 and 0.65 kg/day, respectively). At 42 and 70 days old, the BW of Me-heifers was greater (75.8 ± 2.6 and 91.2 ± 4.6 kg) than control heifers (61.9 ± 2.6 and 77.2 ± 4.6 kg) (p<0.05). There was no difference (P>0.05) in BW at insemination, number of insemination and milk yield between the two groups of cows (p>0.05). Early feeding of Me to heifers in the present study positively affect heifer growth during and early after milk feeding period, confirming previous report. Animal weight at puberty and the subsequent milk production were not influenced by feeding Me. It is possible that Me did not survive long after weaning to continue to express its influence on animal performance. / Agriculture and  Animal Health / M. Sc. (Agriculture)

This thesis describes a series of four experiments designed to evaluate the role of the supply of protein in livestock grazing high quality pasture during mating and during pregnancy. The first two studies investigated the effects of high crude protein content of spring or autumn re-growth pasture on the reproductive performance of dairy cows and of ewes at mating. The last two studies investigated how the dietary supply of protein, body condition and their interactions contribute to the breakdown of immunity during the peri-parturient period in ewes and investigated underlying endocrine mechanisms. In the first study (Chapter 3) cows were blood sampled via the tail vein during the breeding period in spring. Plasma was then analysed for urea concentration. Cows with high plasma urea (HPU) or low plasma urea (LPU) were defined as those with plasma urea concentrations of ≥ or < 44.9 mg/dl respectively. Lactating cows (n = 200) were also categorized into high milk producers (HMP) or low milk producers (LPM) relative to an average daily yield of 26.6 l/d. Pasture clipping showed an average pasture CP (crude protein) content of 223 g/kg DM. Concentrations of plasma urea ranged from 26.6 to 64.4 mg/dl. No correlation was observed between plasma urea concentration and either reproductive indicators or milk parameters. Mean blood urea concentration of HPU cows was 50.8 compared to 38.5 mg/dl in LPU cows. There was a trend for more animals (P = 0.09) in the HPU group than in the LPU group not to return to oestrus. Cumulative pregnancy rate in HPU and LPU was similar except at week 6 after the start of mating when more (P < 0.01) HPU than LPU cows were pregnant. Calving to conception interval, calving interval and interval between conception and first service were similar (P > 0.05) between HPU and LPU cows. Gestation length, calving rate, milk yield and milk components were also similar (P > 0.05) between LPU and HPU cows. There was no difference (P > 0.05) in plasma urea concentrations between HMP and LMP milk producers. However, calving to conception interval, interval between calving and first service and calving interval were longer (P < 0.001), submission rate higher (P < 0.001) and NRR (Non-return rate) higher (P < 0.05) in LMP than HMP. The number of services, the interval between first and second service, gestation length and CR (calving rate) were similar (P > 0.05) between HMP and LMP cows. HMP had lower (P < 0.001) milk protein and fat concentrations than LMP cows. This information indicates that, despite the fact that plasma urea was consistently higher than levels in the literature which have been associated with reduced fertility in dairy cows; no impairment of reproductive performance was observed. In the second experiment (Chapter 4) mature and dry Coopworth ewes were blocked by weight, body condition and previous prolificacy (high, HP vs low twinning frequency, LP) into two groups and thereafter randomly allocated to diet which were designed to provided either 1) high protein (163 g/kg DM, ryegrass/red clover pasture, HPP) or low protein (119 g/kg DM, hay and barley grain, HB) supply at joining. These were designed to provide high and low plasma urea concentration. Over a period of 17 days, ewes recorded as mated were examined by laparoscopy, at which time there was no difference in blood urea concentration (58.6 vs 56.1 mg/dl) between HPP and HB groups. Fifty days after the start of joining the number of foetuses present was counted using ultrasonography. As a consequence of lack of difference in the plasma urea concentration, irrespective of treatment group, individual animals were categorized into high (HU) and low plasma urea (LU) status based on whether plasma urea concentration was higher or lower than the sample mean of 51.5 mg urea/dl. Lambs which weighed greater than the mean plus one standard deviation for their litter size were classified as oversize. Ovulation rate and conception rate were similar (P > 0.05) between HPP and BH and between HU and LU ewes. Ewes with previous high reproductive performance (HP) as would be expected had higher ovulation rate (P < 0.001) and conception rate (P < 0.01) than LP ewes. Embryo losses was not (P = 0.06) different between HB and HPP ewes. Urea category (HU vs LU) did not (P > 0.05) influence embryo mortality. Foetal loss, neonatal loss, total reproductive loss and mean lamb birth weight was were not affected by diet, nor urea category (P > 0.05). Single ovulations had tended (P = 0.08) to contribute to higher embryo loss compared to multiple ovulations, and, single foetuses suffered higher (P<0.001) losses compared to multiples. While the study did not achieve large differences in plasma urea concentrations between diets, the levels of plasma urea operating were high yet reproductive wastage rates were similar to those recorded in the literature. Together with similar apparent lack of effect on a high plasma urea environment, the data suggest either that previous findings from controlled studies have a more complex aetiology or that pastoral animals can adapt to high tissue ammonia/urea status. The third trial (Chapter 5) was designed to provide information on the supply of amino acids to the abomasum from protein supplementation which have previously been found to overcome dietary scarcity associated with limitation of peri-parturient increase in FEC. Twin-suckling ewes were fitted with rumen and abomasal cannulae and grazed a ryegrass/clover sward (C) or the same sward but with a 500 g/h/d protein supplement (S). The trial was designed as a cross-over with two 14 day adaptation periods followed by two five-day digesta-sampling periods. All ewes were treated with anthelmintic 14 days after lambing. Weekly analysis of blood glucose was carried on whole blood and analysis of amino acids in plasma. The flows of amino acids (AA) and dry matter (DM) at the abomasum were measured during both sampling periods using intra-ruminally infused markers. Live weight and faecal egg count (FEC) were recorded weekly. Diurnal variation in AA flow at the abomasum peaked between 12:00 and 15:00 h and was greatest in S ewes. Flows of AA, including DAPA, were increased by supplementation by 16%, while sulphur amino acids (SAA) were the most enhanced (by 21%) and flows of leucine, lysine, glutamine and aspartate were increased by about 20%. There were significant time effects in rumen and abomasal pH (P < 0.01; in both cases in both periods) reflecting increase in pH after 09.00 h. During Period II, rumen pH in digesta of C ewes was significantly higher (P < 0.001) than that of S ewes (6.7 ± 0.05 vs 6.4 ± 0.05 for C and S ewes, respectively). Plasma AA concentrations (P < 0.01) were lower in S ewes 21 days after parturition, but similar (P > 0.05) to those of C ewes at other times. Forty-three days after lambing (after cross over), the order was reversed as plasma methionine and cysteine concentrations of C ewes became low (P < 0.05). These changes in plasma AA were accompanied by changes in body condition score between day 23 and 70 post-partum whereby C ewes lost more body condition than S ewes. There was evidence for a lower FEC in S ewes, being 46 vs. 670 epg, respectively for S and C groups (P = 0.08) 21 days after anthelmintic treatment. There were higher (P < 0.05) blood glucose levels in C compared to S ewes at day +35 relative to lambing which was reversed and significantly higher (P < 0.01) for S ewes by day +56 from lambing (after treatments were reversed). There was no significant effect of treatment on live weight and lamb performance. There are limited data in amino acid supply on lactating ewes on pasture and the present study contributes additional information on the supply of amino acids at the abomasum. The prediction that flow rates that sulphur amino acids may have been enhanced to the greatest degree could be significant since sulphur amino acids are needed for the synthesis of glutathione for immune response. It can be calculated that supplementation to supply the quantities of S-amino acid at pasture would be needed, since it would not be possible for sheep to increase pasture intake to achieve similar S-amino acid flow. Increase in bypass amino acids in S ewes at certain times in the day probably suggests influence by protein supplementation at certain times of the grazing cycle. Reduced plasma free amino acids at day +21 relative to lambing, may indicate sparing of body protein breakdown by protein supplementation. However, the difference in blood glucose on day 35 and day 56 may indicate re-adjustment of hormonal settings, responsible for nutrient partitioning. The last study (Chapter 6) used ewes during the peri-parturient period on pasture. Eighty pregnant ewes were allocated into four groups balanced for anticipated number of lambs. Group 1 had a high body condition score (BCS) of 4.0 which was maintained throughout pregnancy by pasture allowance (HM; n = 20). Group 2 (n= 40) had medium body condition (BCS 3.0) and were split into two subgroups; one was offered pasture to allow gain of condition (MH; n = 20) and the second allowed to lose condition by offering a low grazing allowance (ML; n = 20). Group 3 were thin ewes (BCS 2.4) and pasture allowance was designed to maintain this condition (LM; n = 20). These feeding regimes were maintained for 3 weeks from week -8 of pregnancy. During week -5 to -4 all ewes were acclimatized to a protein supplement (60 g/d). A glucose tolerance test (GTT) was conducted during week -4 after which half of the ewes in each group were offered a protein supplement at the rate of 500 g/d, creating –S and –NS groups. During wk -2, a second GTT was carried out. Animals were treated with an anthelmintic 3 wks before lambing, and were then challenged with a dose of 10 000 Teladorsagia circumcincta larvae on weeks -2 and -1 relative to lambing. Weekly recording of FEC, live weight and body condition was carried out. Lambs were weighed within 24 h of birth and again at 44 and 65 d of age. Computed tomography body scanning was carried out on ewes at weeks -8, -3 and +8 relative to lambing. There were no differences (P > 0.05) in lamb performance due to body condition or protein supplementation. FEC of all groups was low (≈ 9 peg) and there was no (P > 0.05) significant difference between ewes of different body condition or due to effects of protein supplementation. Ewes bearing/bearing multiple lambs had the highest FEC at day -32 and +12 relative to lambing, which was significant (P < 0.05) on the latter date. There were no significant effects of supplementation on parasite status. There were differences in basal plasma glucose concentration between groups (P < 0.001), being highest in HM/S and least in ML/NS ewes and was generally higher (P <0.001) during GTT 2 than GTT 1. Ewes carrying a single foetus had higher (P <0.001) basal glucose than those carrying multiple lambs (2.2 vs. 1.7 mmol/L, respectively). Other plasma glucose response indexes were similar (P <0.05) between groups. There were differences in insulin responsiveness between groups (P < 0.001), being highest in MH/S and least in ML/S ewes. Insulin responsiveness tended (P = 0.06) to be lower during GTT 1 than GTT 2, but was higher (P < 0.01) in ewes carrying singles than multiples. There was tendency for higher though non-significant, basal insulin concentrations in HM ewes. Insulin trends over time after glucose infusion suggest greater insulin response at GTT 1. Basal insulin was not correlated with CT muscle weight. Despite differences in body muscle mass at the start of the trial and differences induced by nutrition during late pregnancy, positive gains in muscle mass occurred during early pregnancy and muscle mass was similar in all groups by day 56 of lactation. Animals with greatest fat content at parturition (HM) mobilised the greatest amount and those with least fat (LM) deposited fat during lactation. Further experimentation may consider the use of the hyperinsulinemic-euglycemic clamp approach to more precisely estimate whether hormonal re-setting through insulin resistance may be involved in relaxation of immunity during the peri-parturient period.

Il periparto della bovina da latte è caratterizzato da processi infiammatori, che aumentano la vulnerabilità delle vacche alle malattie tipiche peripartali, spesso dovute a patogeni occasionali. In tale periodo, si hanno notevoli variazioni metabolico-fisiologiche, che si evidenziano con la tipica risposta “di fase acuta”, caratterizzata dall’aumento delle proteine positive di fase acuta (es. aptoglobina) e di alcuni specifici metaboliti (es. metaboliti reattivi all’ossigeno) ma anche dalla diminuzione delle proteine negative di fase acuta (es. albumina, colesterolo, PON). In queste prove si è cercato di attenuare e/o modulare tali fatti infiammatori mediante trattamenti specifici caratterizzati dalla somministrazione di: una citochina antinfiammatoria (interferon-alfa) due settimane dal parto per via orale con 1000 UI/Kg (1° prova), 0,5 UI/Kg (2° prova), un antibiotico (tilosina) a circa 10 giorni prima del parto per via intramuscolare, in tre giorni consecutivi ed un farmaco antinfiammatorio (acido acetilsalicilico) nel pre e post parto per via orale con un dosaggio di 30g/d a giorni alterni. L’interferone-alfa ha mostrato un effetto pro-infiammatorio, verosimilmente dovuto alla persistenza della citochina nel rumine (confermata dalla prova in vitro); di qui il ritorno in bocca con il bolo ed una reiterazione dell’effetto, quale fosse un alto dosaggio. La tilosina non ha modificato i processi infiammatori, probabilmente per l’effetto limitato nel tempo degli antibiotici. L’unico trattamento che ha modulato i fatti infiammatori e migliorato talune performance delle bovine trattate è stato quello con l’acido acetilsalicilico. / The transition period in dairy cows is characterized by inflammatory processes, which can contribute to the of their increased susceptibility to periparturient diseases, health disorders and lowered performance. During that phase, dairy cows show metabolic and physiological changes characterized by the rise of positive acute phase proteins (i.e. haptoglobin) and some specific metabolite (i.e. ROS), besides a reduction of negative acute phase proteins (i.e albumin, lipoproteins, PON, etc.). The aim in this study was the attempt to reduce and/or to prevent inflammations, with specific treatment: an antinflammatory cytokine (interferon-alfa) before calving about 1000 UI/Kg/day (1st trial), 0.5 UI/Kg (2st trial) per os, an antibiotic parenterally (tylosin) 10 days before calving and a conventional antinflammatory drug (acetylsalicylic acid), about 30 g/day orally before and after calving. Interferon- increased inflammatory response maybe due to a high-dose, because the cytokine (whom activity site is oral cavity) showed to be persistent in the rumen and renewed the cytokine effect with rumination. The use of an antibiotic (tylosin) did not change the inflammatory status of the dairy cows. The oral administration of Acetylsalicylic acid has otherwise reduced the inflammatory effect and improved the performance of treated dairy cows.

Il processo infiammatorio è un meccanismo di difesa aspecifico innato, che costituisce una risposta protettiva dell’organismo a vari tipi di insulto (infezione, danno tissutale, trauma, stress, malattie autoimmune,). Esso comporta il rilascio in circolo di mediatori pro-infiammatori (es. citochine) and anti-infiammatori (es lipossine ed alcune citochine). Le citochine pro-infiammatorie inducono effetti infiammatori (es. anoressia e febbre) e stimolano la risposta di fase acuta (APR). Invece, le lipossine e le citochine anti-infiammatorie tendono ad attenuare l’infiammazione. Gli scopi di questa ricerca erano due: distinguere i soggetti in base al grado di severità della APR dopo il parto, e dopo stimolazione intramammaria con lipopolisaccaride (LPS) in bovine da latte sottoposte a diversi stress metabolici (NaCl, BHB, EuG e IpoG). I soggetti EuG e BHB hanno mostrato una APR più severa rispetto a IpoG e NaCl. Un ulteriore scopo è stato proposto un indice composto da alcune proteine di fase acuta al fine di stimare i processi infiammatori e le conseguenze epatiche (PICE). Le bovine con PICE più basso prima del parto, avevano più alti livelli plasmatici di citochine pro-infiammatorie e lipossine prima del parto (e mostravano una APR più severa dopo il parto), anche in assenza di sintomi clinici. / Inflammation is the innate, non-specific response of the host to disturbances in his homeostasis caused by infection, tissue injury, stress, trauma, neoplastic growth, immunological disorders. It involves pro- (e.g. cytokines) and anti-inflammatory mediators (e.g. lipoxins, some cytokines). The pro-inflammatory cytokines induce inflammatory effects (e.g. anorexia, fever) and play key roles in the stimulation of acute phase response (APR). The lipoxins and anti-inflammatory cytokines tend to mitigate the inflammation. Two were the aims of this research: to investigate in dairy cows the severity of APR at calving time as well as after intramammary lypopolysaccharide (LPS) administration in cows challenged with hyperinsulinemic hypoglycemic (HypoG, n=4), hyperinsulinemic euglycemic (EuG, n=5), hyperketonemic (BHB, n=4) and control (NaCl, n=6) clamps. Plasma samples were assayed for a wide metabolic and inflammatory profile. With respect to HypoG and NaCl animals, more severe APR was observed in EuG and BHB. A further aim was the proposal of an Index, composed by several acute phase proteins, to estimate Inflammatory Processes and Hepatic Consequences (IPHC). The dairy cows with lower IPHC after calving, had higher plasma levels of pro-inflammatory cytokines and of lipoxins before calving (and showed a stronger APR after calving); this was seen also in absence of clinical symptoms.

Aufgrund der zu erwartenden Klimaveränderungen, insbesondere durch eine Erhöhung der Temperaturen und einer Zunahme der Extremsituationen (Hitze- und Kälteperioden), sollte vermehrt über Effekte von Hitzestress auf das Wohlbefinden und Leistungsvermögen von Tieren nachgedacht werden. Um den Einfluss von klimatischen Bedingungen (Temperatur und Temperatur-Humiditäts Index) auf die Gesundheit und das Leistungsvermögen von Milchkühen zu untersuchen, wurden drei Studien durchgeführt. Zuerst wurden die Auswirkungen des Temperatur-Humiditäts Index (THI) auf die Behandlungsfrequenz von Milchkühen ermittelt. Hierfür wurden die Daten aus den Bestandsbüchern von 2003 und 2005 von acht Milchviehbetrieben ausgewertet. Die Behandlungen wurden in vier Komplexe unterteilt: Stoffwechsel, Fruchtbarkeit, Euter und Klauen, wobei 37,4% der Behandlungen zum Stoffwechsel-, 32,9% zum Euter-, 21,6% zum Fruchtbarkeits- und 8,1% zum Klauenkomplex gehörten. Es zeigten sich ein tendenzieller Anstieg der Stoffwechselinzidenzen mit steigendem THI und ein nicht signifikanter Anstieg von Euterbehandlungen mit abfallendem THI. Die zu analysierenden Daten bezüglich des Einflusses auf das Leistungsvermögen wurden im Rahmen eines einjährigen Feldversuches vom April 2010 bis März 2011 aufgenommen. Hierfür wurden aus einem Pool von niedersächsischen Milchviehbetrieben 20 Betriebe mit unterschiedlichen Haltungssystemen (gedämmte und ungedämmte Laufställe mit und ohne Weidegang) ausgewählt. Auf diesen Betrieben wurden klimatische Werte (Stalltemperatur, relative Stallluftfeuchtigkeit und THI) als auch Herden- bzw. tierindividuelle Leistungsdaten (4% fettkorrigierte Milchmenge (FCM), Milchinhaltsstoffe und somatischer Zellscore (SCS)) anhand von Tankmilchproben bzw. Einzeltiermilchproben im Rahmen der Milchleistungsprüfung erfasst. Insgesamt wiesen die Untersuchungen unterschiedlich hohe Hitzestresseffekte auf die Milchleistung, Milchinhaltsstoffe und den SCS in den verschiedenen Haltungssystemen auf. Für die Milchmenge ergaben sich Regressionskoeffizienten von -0,12 kg FCM/THI und -0,11 kg FCM/THI bei gedämmten Laufställen ohne und mit Weidegang sowie -0,21 kg FCM/THI für Außenklimaställe ohne und mit Weidegang. Für den SCS ergaben sich bei den Stallhaltungssystemen Regressionskoeffizienten von +0.03 SCS/THI für gedämmte Systeme und +0,07 SCS/THI für Außenklimaställe. Basierend auf den Ergebnissen der Arbeit kann geschlussfolgert werden, dass Milchkühe in Niedersachsen während der Sommermonate Hitzestress ausgesetzt waren, wohingegen sich die Auswirkungen je nach Haltungssystem differenziert darstellten. Des Weiteren konnte gezeigt werden, dass in dem System mit gedämmtem Dach niedrigere Auswirkungen mit steigendem THI zu finden waren.