No description available.

The dairy industry today is beginning to dedicate more focus on the growth of the calf from birth to first breeding to better improve the milk production as well as the overall performance of the individual cows. While the development of the rumen is one of the most vital contributors to the performance of the calf, it remains unknown what molecular mechanisms are responsible for the development of the rumen, and more specifically the proliferation of rumen epithelial cells. The objectives of this study were to investigate the existing data on rumen development through meta-analysis and to explore the effects of sodium butyrate and lipopolysaccharide (LPS) on rumen development in calves through experiment. In the first study a meta-analysis was performed to summarize the literature on calf performance and derive equations that relate rumen (e.g., rumen pH, reticulorumen weight, papillae area) and non-rumen factors (e.g., feed composition, form of feed, housing) to animal performance (e.g., intake of milk replacer (MR), starter, and forage; average daily gain (ADG); and feed efficiency). We looked at four different relationships to further investigate the connections between rumen, non-rumen, and performance factors. In the first and second relationships of interest, the effect of dietary and environmental variables on rumen variables and performance variables were examined, respectively. The third relationship of interest was how rumen variables influenced performance variables. The final relationship of interest was investigating the additive effects of the rumen, dietary, and environmental variables on the performance variables. Forward selection, multiple regression was used to derive equations to select variables that explained variation in the response variable in each model. Results showed that the variation in calf ADG was explained by daily forage intake, calves that were weaned, total starter intake, and total MR intake (concordance correlation coefficient (CCC) = 0.976). The variation in feed to gain ratio was explained by the weight of the ruminal contents, daily forage, MR, and starter intakes, percent of starter in the diet, and total starter intake (CCC = 0.992). The variation in daily forage intake was explained by the percent of the diet that was starter or MR (CCC = 0.998). The variation in daily starter intake was explained by the percent of acid detergent fiber in the starter, a pelleted starter (versus a texturized), diets including starter and forage (versus a milk replacer only diet), and the percent of the diet that was MR (CCC = 0.998). The variation in daily MR intake was explained by the percent of the diet that was starter, final body weight, ruminal propionate concentration, and daily starter intake (CCC = 0.918). Based on these analyses, although dietary and environmental factors are closely associated with calf performance, ruminal factors such as volatile fatty acid (VFA) concentration and ruminal contents appear to have additional, additive influences on calf performance. In the second study, 24 Holstein bull calves were challenged with oral doses of LPS and sodium butyrate. The hypothesis here was that LPS and sodium butyrate would instigate rumen cell proliferation independently and additively. Calves were assigned to one of four treatments: control (CON; n=5), butyrate (BUTY; n=5), LPS only (LPS-O) (n=6), or LPS plus butyrate (LPSB; n=6). All treatments were administered orally twice daily consisting of either: 0.9% saline (CON); 11 mM sodium butyrate (BUTY); LPS ranging from 2.5 to 40 µg/kg metabolic body weight (BW0.75, LPS), or both butyrate and LPS (LPSB). Calves were fed milk replacer (22% CP, 20% fat, as-fed) and starter (20% CP, 3% fat, as-fed) based on metabolic BW, or about 12% BW of MR and 3% BW of starter. Feed intake, fecal and respiratory scores, and rectal temperature were recorded daily. Calf BW, hip height, jugular blood samples, and rumen content samples (via oroesophageal tube) were collected weekly. Calves were weaned at 6 wk of age and euthanized at 8 wk of age, whereupon ruminal weights and ruminal samples for papillae area and epithelial thickness were collected. Blood and rumen samples were analyzed for concentrations of beta-hydroxybutyrate, glucose, LPS-binding protein, and VFA. Data were analyzed as a 2x2 factorial with the repeated effect of week. Three non-orthogonal contrasts (CON versus the average of all other treatments; LPS-O versus LPSB, and LPSB versus BUTY) were investigated. Feed intake, health measures, and blood metabolites did not differ by treatment. Calf BW increased by week (P < 0.0001). Irrespective of week, LPS calves weighed more and had higher ADG than BUTY calves (P = 0.020). Irrespective of week, withers height was greater in LPS compared to CON (P = 0.006). Rumen pH and rumen VFA concentrations did not differ by treatment but did decrease and increase, respectively, with week in conjunction with increased starter intake. Total empty forestomach (P = 0.014) and reticulorumen weights (P = 0.012) were greater in LPSB compared to BUTY. Overall, LPS and sodium butyrate appeared to have synergistically affected some, but not all rumen measurements without affecting calf growth, intake, or health. Results from the meta-analysis emphasize the importance of continuing to focus on the solid feed intake of the calf from birth through weaning. Implications from the LPS study are imperative to other dairy scientists who will attempt to further study the effects of LPS on the rumen. / Master of Science in Life Sciences / Dairy calves are born with an under-developed stomach. The stomach has four compartments: the rumen, reticulum, omasum, and abomasum. The rumen is the largest component where finger-like projections called papillae grow to absorb nutrients for the calf. It is vital to the calf that the rumen develops not only the papillae to absorb nutrients but also to foster a microbe-rich environment so the microbes can act as a defense mechanism for the calf to aid in fighting disease. While it is known that things like solid feed support the development of the rumen, the mechanism behind how that is happening still remains unclear in the literature. The objective of this study was first to better understand the relationships that exist in the literature between dietary, environmental, and ruminal factors, and second to investigate the claim that certain components of the bacteria in the rumen are stimulating rumen development independently and additively with sodium butyrate. In order to investigate the relationships amongst the dietary, environmental, and ruminal parameters, a computer program called R Studio was used to analyze over 30 different models that extracted data from a database that included a collection of 36 studies from the literature. This is also known as a meta-analysis. The associations of interest that we found were: average daily gain (ADG) of the calf was associated with daily forage intake, calves that were weaned, total starter intake, and total MR intake. Feed efficiency of the calf was associated with the weight of the ruminal contents, daily forage, milk replacer (MR), and starter intakes, percent of the diet composed of starter, and total starter intake. Daily forage intake was associated with the percent of the diet that was starter or MR. Daily starter intake was associated with acid detergent fiber in the starter, a pelleted starter (versus a texturized starter), diets including starter and forage (versus a MR only diet), and the percent of the diet that was MR. Daily MR intake was associated with the percentage of the diet that was starter, final body weight (BW), ruminal propionate concentration, and daily starter intake. These relationships emphasized that although dietary and environmental factors are more closely associated with calf performance, ruminal factors such as rumen contents and volatile fatty acid concentrations appear to have additional, additive influences on calf performance. The second part of the study objective was to explore an idea that, to our knowledge, has not been published in the literature. In the second study, 24 dairy calves were challenged with oral doses of a gram-negative bacteria lipopolysaccharide (LPS), and a short-chain fatty acid sodium butyrate. The hypothesis in this study was that the LPS and sodium butyrate would trigger metabolic pathways on the rumen cell membranes to a greater extent together, versus independently, to increase the amount of cells growing. Calves were assigned to one of four treatments: control (CON), butyrate (BUTY), LPS only (LPS-O), or LPS plus butyrate (LPSB). To study this effect, each treatment group was administered their respective treatment orally as a liquid twice daily. To measure the results, the following data was collected: feed intake, fecal and respiratory scores, rectal temperature BW, hip and withers height, blood samples, rumen content and pH samples, papillae area, epithelial thickness, and organ weights. Blood and rumen samples were analyzed for blood metabolites and volatile fatty acids concentrations respectively. Data were analyzed and results showed no difference amongst feed intake, health measures, rumen pH, rumen VFA concentration, and blood metabolites by treatment. Calves on the LPS treatment weighed more and had higher ADG than BUTY treatment calves. Withers height was higher in the LPS group when compared to CON. Stomach weights were higher in the LPSB group when compared to the BUTY group.

Raising replacement heifers consumes a large portion of dairy and beef producers' income. An ultimate goal of producers is to decrease inputs and maximize outputs to produce fertile replacement heifers. Manipulating early postnatal growth and development through diet enables this practice to be successful. Puberty is greatly influenced by body weight (BW). Once heifers reach puberty, they become fertile and can achieve their reproductive potential. Growth can easily be influenced during the preweaning phase of development. Offering calves a higher plane of nutrition through milk diets prior to weaning hastens development and can lead to an earlier age at the onset of puberty. The objective of the first study was to understand how plane of nutrition influences BW, bone mineralization, and organ growth during the preweaning phase of development in Holstein calves. Calves offered a higher plane of nutrition experienced greater BW gains, increased bone mineralization, and accelerated organ growth. The second study evaluated plane of nutrition on reproductive development, specifically adenogenesis in Holstein heifer calves. Adenogenesis, or the development of uterine glands, is initiated in the early postnatal period. It involves rapid endometrial epithelial cell proliferation, germinal bud formation, invasion into the stroma, and extensive branching and coiling. Little is known about how nutrition impacts adenogenesis in ungulates, however, this study provided validation that it does drive gland formation. Additionally, this study assessed the influence of exogenous estradiol on reproductive development and adenogenesis when given after the completion of adenogenesis. We can confirm that exogenous estradiol given after the completion of adenogenesis does not alter the outcomes of gland formation. The beneficial effects of feeding a higher plane of nutrition to calves prior to weaning on bone mineral density, organ growth, and adenogenesis may provide new possibilities for understanding the impacts of early nutrition on calf immune responses and productive lifespan of the cow. Collectively, these studies emphasize the importance of nutrition during preweaning growth and development of Holstein calves. / Master of Science

Optimizing forage productivity is essential to reduce pasture seasonality and ensure available forage to meet the nutritional needs of livestock. This study explores the risk-buffering ability of warm-season forages to fill the summer slump gap in production of cool-season grasses. Small plot experiments were initiated in summer of 2008 in Kentland Farm, Northern Piedmont AREC and Shenandoah AREC, Virginia. Treatments included endophyte-infected tall fescue (KY31 E+), endophyte free tall fescue (KY31 E-), novel endophyte tall fescue (MaxQ), Crabgrass in combination with endophyte-infected tall fescue, Teff, Bermudagrass (BG), and Caucasian bluestem (CB). Plots were harvested May through October of 2009 and 2010 at the late boot stage at a cutting height of 10cm. Subsamples were analyzed for dry matter and nutritive value. To assess risk, bootstrap distributions of biomass and quality data were generated by Monte Carlo simulation and compared against an objective function defined as 59 kg ha-1 d-1 forage yield; 10% CP; 60% TDN. Regardless of variability, warm-season grasses produced biomass yields and nutritional values adequate to fill the summer slump from cool-season forages and demonstrated a higher probability of meeting the minimum requirements in July, August and September. Teff was most consistent in meeting the minimum requirements in mid-summer. However, with good conditions for establishment, both BG and CB can help to fill the gap in summer months when compared to cool-season tall fescue. Bootstrap distributions provide producers with a tool that links their production goals with a measurable value of production risk. / Master of Science

Exposure to antibiotics has the potential to increase the incidence and proliferation of antibiotic resistance genes (ARG) in the gut and fecal microbiome. Non-saleable, antibiotic-containing milk from cows treated with antibiotics (waste milk) is commonly fed to dairy calves but the effects of ingestion of antibiotics at an early age on the gut microbiome and the development of ARG in the naive gut are not well understood. Pirlimycin, a lincosamide antibiotic acting against Gram positive bacteria through inhibiting protein synthesis by binding to the 50S ribosome, is commonly used as mastitis therapy. Lincosamides are also considered highly important in human medicine, often used against Staphylococcus aureus and Clostridium difficile infections. Emerging microbial resistance to pirlimycin is of concern for both animal and human health. The objective of this study was to determine the effect of early lincosamide antibiotic exposure on the abundance of ARG in feces of milk-fed calves. Eight female Holstein calves were blocked by age, paired by block, and randomly assigned to pasteurized whole milk (control; n = 4) or milk containing 0.2 mg/L of pirlimycin (treatment; n = 4). Calves were enrolled after receiving two colostrum feedings and were fed 5.68 L of pasteurized whole milk, treatment, or control, divided into two daily feedings, from d 1 to d 50 of age. After weaning calves were fed non-medicated starter grain ad libitum. Fecal samples were collected weekly until 85 d of age and freeze-dried. DNA was extracted using QiaAmp® Fast DNA Stool Mini Kit and qPCR was used to quantify the absolute abundance (gene copies/g of wet feces) and relative abundance (gene copies/copies of 16S rRNA genes) of erm(B), tet(O), tet(W) and 16S rRNA genes. Data was analyzed using PROC GLIMMIX in SAS. Abundance of 16S rRNA genes, tet(O) and tet(W) were not different between control and pirlimycin-fed calves nor were the relative abundance of tet(O) (mean = 0.050 tet(O) copies/16S rRNA genes) or tet(W) (0.561 tet(W) copies/16S rRNA genes). While abundance of erm(B) was higher in pirlimycin-fed calves compared to control calves (6.46 and 6.04 log gene copies/g wet feces; P = 0.04) the relative abundance of erm(B) (0.273 gene copies/16S rRNA genes) in feces of calves was not influenced by treatment. There was an effect of day (P < 0.10) for absolute abundance of tet(O), tet(W), and erm(B) indicating that the levels change with time as the fecal microbiome develops. This study suggests that feeding pirlimycin-containing non-saleable milk to growing calves may increase environmental loading of erm(B), which codes for resistance to highly important macrolide and lincosamide antibiotics. Additional research is needed on effects of feeding waste milk to calves on other fecal ARG and on the post-excretion and post-application fate of these genes. / Master of Science

Animal behavior can be used to detect disease and well-being in dairy cattle. In this dissertation, we evaluated the accuracy of an accelerometer to measure step activity, lying time, and lying bouts in pre-weaned dairy calves. The output from the accelerometer was correlated with behavioral measurements taken from video footage. The accelerometer proved to be accurate in identifying step activity (r = 0.99), lying time (r = 0.99), and lying bouts (r = 0.99). The accelerometer was then used to detect behavioral changes occurring around respiratory disease events in pre-weaned calves. Activity declined 1 d prior to clinical disease onset, and this decline persisted for 3 d post-diagnosis. Furthermore, lying bouts declined beginning 2 d prior to diagnosis, and this effect persisted after diagnosis as well. However, aside from a slight reduction in milk intake, feeding behavior was not different between diseased and healthy calves. These data suggest that activity and lying behaviors may be a better measure than feeding behaviors for detection of respiratory disease in pre-weaned dairy calves. Dystocia has detrimental effects on both periparturient dairy cows and newborn calves. We administered a non-steroidal anti-inflammatory drug, meloxicam to periparturient dairy cattle. Treatments included administration prior to calving (MEL-PRE, n = 60), post-calving (MEL-POST, n = 69), or a negative control (CTL, n = 65). We measured the length of labor to determine which cows had easy or difficult calvings. Eutocic MEL-PRE animals produced 6.8 kg/d more milk than eutocic CTL. Regardless of calving difficulty, MEL-PRE animals produced more milk fat, protein, and lactose (kg/d) than the CTL. Additional research is needed to determine appropriate treatments for dystocic calvings. Calves born during the above trial were monitored to determine if meloxicam administration prior to calving impacted newborn calf health and behavior. Calves born difficultly displayed fewer lying bouts for the first few days after birth when compared to calves born easily. No effect of treatment or calving difficulty was noted on calf health. Additional research examining intervention strategies aimed at improving well-being of calves born difficultly is needed. / Ph. D.

Neste trabalho, foi pesquisada a eficiência de abrigos individuais para bezerros, a partir de índices de conforto térmico (carga térmica radiante, índice de temperatura de globo e umidade e índice de globo negro) calculados com base na temperatura ambiente, temperatura de globo negro e umidade relativa do ar, comparando-se abrigos cobertos por telha de cimento celulose ou telha de cimento amianto comercial. O experimento foi implantado num sistema de abrigos convencionais, tipo boxe, com cinco tratamentos diferentes e cinco repetições por tratamento (um bezerro por repetição), durante os meses de setembro a novembro de 2002. Foram registradas variáveis fisiológicas de termorregulação (freqüência respiratória e temperatura retal). As telhas de cimento celulose foram caracterizadas por meio de testes físicos e mecânicos com resultados aceitáveis. Estimou-se o custo final da produção da telha de cimento celulose, que se mostrou vantajoso em relação a outras opções de cobertura com telha cerâmica. Os abrigos expostos ao sol e cobertos com telha de cimento amianto apresentaram os índices menos satisfatórios quanto ao conforto térmico animal, em relação aos demais abrigos também expostos ao sol. Já os abrigos cobertos com telhas de cimento celulose apresentaram os melhores índices de conforto térmico animal, quando estes estavam dispostos em área sombreada. Os resultados das variáveis fisiológicas também foram significativamente melhores para os tratamentos posicionado à sombra. Encontrou-se uma relação satisfatória entre os resultados de conforto térmico e os resultados fisiológicos. / This work focused the efficiency of individual housing for calves, based on thermal comfort indexes (radiant thermic load, black globe humidity index and black globe index) that were calculated with ambient temperature, black globe temperature and relative humidity of the air. Animal housing covered with cellulose cement tiles were compared with commercial asbestos cement tiles. The experiment was installed in a system of conventional housing, box type, with five different treatments (one calf per repetition), during the period from September to December 2002. Physiological variables of thermoregulation (respiration rate and rectal temperature) were also registered during the experiment. The roofing tiles of cellulose cement were characterized by physical and mechanical tests with acceptable results. The final cost of the production of the cellulose cement tiled showed to be advantageous in relation to other options of roofing with ceramic tiles. The housing exposed to the sunlight and covered with asbestos cement tiles presented the less satisfactory results for the animal thermal comfort in comparison with the others treatments exposed to the sun. The housing covered with cellulose cement tiles under shade showed the best results of thermal comfort. The results of the physiological variables were significantly better for the treatment positioned under the shade. A satisfactory relation between the thermal comfort indexes and the physiological results were found in the conditions of the present work.

This study was an extension of a study submitted in April 2014 by Sheldon D. Holt entitled “Ambient Temperature, Calf Intakes, and Weight Gains on Preweaned Dairy Calves”. A major component in a profitable dairy operation is the raising of female calves as replacement heifers; but since no direct income is generated by calf raising alone, it is often overlooked as a potential profit area on a dairy farm. Calf management practices that ultimately impact milk productivity and reproductive performance during a heifer’s lifetime begin at birth. This study examines the effect of calf starter intake on calf growth, measuring specifically calf weight. How calf starter intake affected production costs was also examined. Other factors included in the study were seasonal change, hip height, days since birth, and weather conditions. The cost of calf starter is one of the main contributors to total production cost in raising dairy calves. Since the amount of starter intake consumed by the calves in this study was measured by Holt, a cost analysis can be performed using these data. Therefore, the first two objectives of this study are to 1) develop a model which minimizes cost of starter feed (which is a variable controlled by the dairy producer) and 2) use the model developed under objective 1) to find the breakeven point (where the cost of an input is less than or equal to the value gained from that input) and conduct sensitivity analysis with respect to this point. Although an analysis was performed on the data at the close of its collection in 2014 by S.D Holt, there are several econometric issues that were not adequately addressed before these analyses were performed. The following problems have been found in the data: functional form, multicollinearity, heteroskedasticity, and serial correlation. Any interpretation or prediction based on these data, without these issues being resolved, is not reliable. In order for interpretations and predictions based on these data to be valid, the last two objectives of this study are to 3) define in detail the econometric problems that existed in Holt’s study and 4) find and implement solutions to econometric problems that existed in that study.

Neste trabalho, foi pesquisada a eficiência de abrigos individuais para bezerros, a partir de índices de conforto térmico (carga térmica radiante, índice de temperatura de globo e umidade e índice de globo negro) calculados com base na temperatura ambiente, temperatura de globo negro e umidade relativa do ar, comparando-se abrigos cobertos por telha de cimento celulose ou telha de cimento amianto comercial. O experimento foi implantado num sistema de abrigos convencionais, tipo boxe, com cinco tratamentos diferentes e cinco repetições por tratamento (um bezerro por repetição), durante os meses de setembro a novembro de 2002. Foram registradas variáveis fisiológicas de termorregulação (freqüência respiratória e temperatura retal). As telhas de cimento celulose foram caracterizadas por meio de testes físicos e mecânicos com resultados aceitáveis. Estimou-se o custo final da produção da telha de cimento celulose, que se mostrou vantajoso em relação a outras opções de cobertura com telha cerâmica. Os abrigos expostos ao sol e cobertos com telha de cimento amianto apresentaram os índices menos satisfatórios quanto ao conforto térmico animal, em relação aos demais abrigos também expostos ao sol. Já os abrigos cobertos com telhas de cimento celulose apresentaram os melhores índices de conforto térmico animal, quando estes estavam dispostos em área sombreada. Os resultados das variáveis fisiológicas também foram significativamente melhores para os tratamentos posicionado à sombra. Encontrou-se uma relação satisfatória entre os resultados de conforto térmico e os resultados fisiológicos. / This work focused the efficiency of individual housing for calves, based on thermal comfort indexes (radiant thermic load, black globe humidity index and black globe index) that were calculated with ambient temperature, black globe temperature and relative humidity of the air. Animal housing covered with cellulose cement tiles were compared with commercial asbestos cement tiles. The experiment was installed in a system of conventional housing, box type, with five different treatments (one calf per repetition), during the period from September to December 2002. Physiological variables of thermoregulation (respiration rate and rectal temperature) were also registered during the experiment. The roofing tiles of cellulose cement were characterized by physical and mechanical tests with acceptable results. The final cost of the production of the cellulose cement tiled showed to be advantageous in relation to other options of roofing with ceramic tiles. The housing exposed to the sunlight and covered with asbestos cement tiles presented the less satisfactory results for the animal thermal comfort in comparison with the others treatments exposed to the sun. The housing covered with cellulose cement tiles under shade showed the best results of thermal comfort. The results of the physiological variables were significantly better for the treatment positioned under the shade. A satisfactory relation between the thermal comfort indexes and the physiological results were found in the conditions of the present work.

No description available.