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Call number: LD2668 .T4 1959 T68

Call number: LD2668 .T4 1958 A34 / Master of Science

Precision dairy technologies (PDT) are becoming more accessible and are therefore becoming more common on commercial dairy farms and in dairy research. Prior to any use of PDT, one should understand the precision, accuracy and bias of the device by a validations studies before interpreting the behavior measurements. Thus, the objective of the first section of my thesis is to validate ruminating, feeding and resting measurements of a behavior monitoring collar used in the second section. Precision dairy technology is used in heat stress studies to compare behavior of cows exposed to different heat stress treatments or abatement strategies. Heat stress is an important issue to research because it negatively affects cow behavior, physiology, and therefore production in lactating dairy cows. The objective of the second section is to assess the ability of a free choice soaker to reduce heat stress measured utilizing PDT and compare use of a free choice to a soaker in addition to one of the two treatments 1) no mandatory soakings, or 2) two mandatory soakings.

Grain feeding is an important part of a dairy feeding program. Grain supplies energy in a concentrated form and when fed as a supplement to forage permits cows to maintain high levels of production. Also, if the forage is of low quality, additional protein and other nutrients can be supplied with the grain in a concentrate mix. By feeding a balanced concentrate mix, according to individual production, each cow receives the necessary nutrients for production. Dairy cows are usually fed grain individually. During recent years dairy herds have increased in size and milking parlors have been developed in which to milk cows more efficiently. In milking parlors cows are generally fed grain individually. However, the cows are milked so rapidly that there is insufficient time for them to consume more than a few pounds of grain. Cows not consuming all of their grain, while being milked, are left in the stall until the remaining grain is eaten, thus delaying the milking operation or turned out without consuming the allotted amount of grain.

An expert system for identifying cows to be culled, MAXCULL, was programmed to run on an IBM or compatible personal computer . It was designed to be used with Dairy Herd Improvement (DHI) records as an aid in decision making. MAXCULL used fifty-two health, seventeen reproduction, and thirty-nine production rules in the analysis. MAXCULL was initially developed using two expert system tools. VP-Expert and Super Expert both had inductive abilities and were reasonably priced . VP - Expert was selected to continue the development of the MAXCULL system . The program u sed a rule-based method of storing knowledge, which was obtained from literature reviewed in the health, reproduction and management areas. Three blocks of rules were developed. MAXCULL used a backward- chaining control strategy. The information on each cow was obtained from a special report obtained from DHI Provo . The diagnosis from MAXCULL produced an explanation paragraph identifying possible reasons for removing the cow. Twenty herds with DHI records were identified, ten assigned as controls and ten to be evaluated with the MAXCULL system . General linear model procedures were used to compare thirteen variables after using MAXCULL for one year. No significant differences were noted for any of the variables. The chi- square analysis showed that the decisions of MAXCULL were significantly different from the decisions of the manager. The final survey supports the idea that dairy management expertise can be provided to the dairy manager through an expert system.

The relationship of quantity and quality of feed to milk production has been studied for many years. Feeding standards have been developed to systematize feeding of dairy cows according to their requirements. Recently, interest in efficiency of cows in converting feed nutrients into milk has increased.

There is much interest in the nature and quality of the diet consumed by adolescents. To determine whether there are significant associations between diet and gain in height and weight in this age group, the present study analysed data on food intake and weight and height obtained on three occasions over a 30-month period from a total of 326 adolescents aged between 12 and 15 years. Information on sociodemographic and other lifestyle factors, including an indicator of physical activity, was also obtained. Energy intake was found to be a significant positive predictor of both height and weight gain. In addition intake of fat, calcium and riboflavin were found to be significant positive predicators of height gain and intake of carbohydrate and starch significant positive predictors of weight gain. After controlling for energy intake only riboflavin approached significance as a positive predictor of height gain. A food group analysis identified intake of dairy foods as a significant predictor of height gain. Although statistically significant the dietary predictors explained only a small proportion of the variability in height and weight (≤3.5%). Given the difficulties in obtaining complete dietary records from this age group and the generally adequate nature of the diet in the study group, the small proportion of height and weight gain explained by diet is not unexpected. Nevertheless the nutrient predictors identified are consistent with nutrient requirements for growth during adolescence and highlight the importance, for this age group, of an adequate intake of nutrients specifically provided by dairy foods. Few significant associations were found between growth rates and the sociodemographic and the lifestyle factors measured in this study. The ethnic diversity of the study sample may have contributed to this outcome.

Although the occurrence of ketosis is a postpartum phenomenon, recent studies have focused on the prepartum period as key in the development of the disorder. Indicators of prepartum energy status, such as depressed dry matter intake (DMI) and elevated plasma non-esterified fatty acid (NEFA) concentrations have been associated with the occurrence of ketosis. The objective of this study was to investigate the role of phosphoenolpyruvate carboxykinase (PEPCK) in the periparturient and ketotic cow. The enzyme PEPCK catalyzes the rate limiting step in gluconeogenesis in hepatocytes. Whereas, in adipocytes, it has been suggested that PEPCK functions in the synthesis of glycerol for the formation of triacylglycerol (TAG) when plasma glucose concentrations are low. Thirty-four pregnant multiparous Holstein dairy cows were fed a single prepartum ration that consisted of 50% oat hay, 18% corn silage and 32% grain mix (DM basis). The ration was formulated to meet or exceed NRC requirements of 14% CP and 1.6 Mcal/kg NE[subscript L]. At calving, cows were transitioned onto one of two postpartum diets: control (n=14) or 3.5% supplemental fat (n=20). The postpartum diets, fed from wk 1 to 3, were formulated to isonitrogenous and to meet NRC requirements. Both diets consisted of 25% alfalfa, 25% corn silage and 50% grain mix. The control and fat diets contained 17.2 and 17.6% CP and 1.67 and 1.74 Mcal/kg NE[subscript L] respectively. Liver biopsies from 28 cows and adipose tissue biopsies from 6 cows were collected at -14, 2 or 3 and 14 d relative to calving. Tissue samples were analyzed for PEPCK mRNA and activity. All results were analyzed by period: prepartum (-21 to -2 d), freshening (2 to 7 d) and postpartum (8 to 21 d). In a previous study in our lab, 25 and 75% cows on the control and fat diets, respectively, experienced ketosis. In the current study there a 40% occurrence of ketosis for both control and fat diet groups. The high occurrence in both diets may be attributed to the rapid transition from the dry cow ration (70:30 forage to concentrate ratio, DM basis) to the lactating cow ration (50:50 forage to concentrate ratio, DM basis). The cows on the fat diet had lower serum glucose at freshening. Cows with ketosis had higher prepartum body weights (788 kg) than non-ketotic cows (743 kg; P<.1). No prepartum differences were seen in body condition score, DMI, NE[subscript L] balance, NEFA, glucose or ��-hydroxybutyrate concentrations were detected between ketotic and non-ketotic cows. Expression of adipose PEPCK mRNA was not different between ketotic and non-ketotic cows. However, hepatic PEPCK mRNA expression was higher in non-ketotic cows at freshening when compared to ketotic cows. Cows that experienced ketosis had lower hepatic PEPCK activity prepartum (6.6 vs. 9.3 units /min/g protein) and postpartum (7.6 vs. 10.2 units/min/g protein; P<0.5) when compared to non-ketotic cows. Our data indicated that hepatic PEPCK is a useful prepartum predictor of a cows susceptibility to ketosis. / Graduation date: 1998

Phosphorus (P) is a pollutant in freshwater systems because it promotes eutrophication. The dairies in the North Bosque and its water body segments import more P than they export. Dairies accumulate P-rich effluent in lagoons and use the wastewater for irrigation. As more P is applied as irrigation than is removed by crops, P accumulates in the soil. During intense rainfall events, P enters the river with stormwater runoff and can become bio-available. Reducing the P applied to the land would limit P build up in the soil and reduce the potential for P pollution. Since wastewater P is associated with suspended solids (SS), the flocculants, poly-DADMAC and PAM, were used to reduce SS. To precipitate soluble P from the effluent, NH4OH was added to raise the pH. Raw effluent was collected from a dairy in Comanche County, TX, and stored in 190-L barrels in a laboratory at Texas A&M University. Flocculant additions reduced effluent P content by as much as 66%. Addition of NH4OH to the flocculated effluent raised the pH from near 8 to near 9, inducing P precipitation, further reducing the P content. The total P reduction for the best combination of treatments was 97%, a decrease from 76 to 2 mg L-1. If this level of reduction were achieved in dairy operations, P pollution from effluent application would gradually disappear.