Call number: LD2668 .T4 1931 A34

Call number: LD2668 .T4 1960 P34

No description available.

No description available.

No description available.

The objectives of this study in the Nakuru District of the Kenyan Highlands, the major milk sources for the Nairobi milk market, were to evaluate current dairy cattle rearing and feeding practices, and suggest efficient feeding management strategies on large and small-scale commercial dairy farms. 139 small-scale farms with 738 dairy cows were surveyed and 6 large-scale dairy farms with 4379 dairy cattle. On the small farms, high mortality rates, cost of AI, and disease were the major causes of poor reproduction leading to a lack of replacement stock. Feeding systems used were: 24% free grazing system, 33% semi-zero grazing, 40% zero grazing, and 3% rotational grazing, but limited feeds were available – crops and feed crop residues, cut grass on the roadside, neighbouring farms with some purchased hay and straws in the dry season. After weaning, feed supplements were rarely given to calves, priority being given to milking cows, explaining the few replacement stock kept and their high mortality. The six large scale farms were from 200 to 3500 acres with milk production, cereal crops, fodder crops, the scale of replacement dairy stock and hay to other dairy farms the main activities with land allocated 65% to livestock, 20% to cash crops (Barley and Wheat), 10% to fodder crops and 5% to other land-uses. Replacement heifers for sale were insufficient to meet demands from small-scale farms. Grazing systems were mainly extensive with supplements fed at milking.  All the farms depended on planted forage grasses, mainly: Rhodes grass, Star grass, Sudan grass and Kikuyu grass. Calf mortality rate (10-18 %) was high caused mostly by respiratory diseases and East Coast Fever. Extended age at first calving (>31.8 ± 4.5 months), long calving intervals (> 406 days) and low average milk yields (6.81/day ± 3.9) for all breeds, occurred. Production and reproductive performances needs to be addressed by proper nutrition. Suitable pasture grasses, legumes and fodder crops not currently being used have been identified as potential options to complement the existing pasture. Among these are: Guinea grass (panicum maximum), Cynodon dactylon, Buffel grass (Cenchrus ciliaris), Naivasha star grass (Cynodon plectostachyus) and Rhodesian star grass (Setaria sphacelata). Other studies examining supplementation of animals on low quality pastures with the above feeds resulted in increased body weights and milk yields. The greatest potential seems to be supplementing with home-grown proteinaceous feedstuffs such as Leucaena leucocephala, Calliandra, Sesbania or food crop residues like groundnut, cassava, sweet potato vines or pigeon-pea leaves and stems. Farmers could increase their pasture land productivity by establishing fodder grass, fodder shrubs and food crops as intercropping, hedgerows and along contour bands.

Master of Science / Department of Animal Sciences and Industry / Barry J. Bradford / Declining ground water supplies are putting significant pressure on the dairy industry in the United States. The water needed for forage production represents the great majority of total water use on most dairy farms, posing a major challenge in the pursuit of improved drought resilience. Teff (Eragrostis tef), a drought-tolerant annual grass (C4 physiology) native to Ethiopia, could prove an attractive alternative to traditional forage crops. While teff grass has potential to fit the needs for forage production in water-stressed regions, very little is currently known about its nutritional characteristics and whether it can support high levels of milk production by dairy cattle. An experiment was conducted to investigate the effects of variety and cutting age on dry matter yield, nutritive values, and digestibility of teff grass. Eighty pots were blocked by location in a greenhouse and randomly assigned to 4 teff varieties (Tiffany, Moxie, Corvallis, and Dessie) and to 5 cutting ages (40, 45, 50, 55, or 60 d after planting [DAP]). Results from this study indicate that, under greenhouse conditions, the first cutting of teff grass should be harvested at 45 to 50 DAP to optimize forage yield, quality, and digestibility in that cutting and in subsequent cuttings. A second experiment was conducted to assess the productivity of lactating dairy cows fed diets with teff hay as the sole forage. Nine multiparous Holstein cows were randomly assigned treatment sequence in a 3 × 3 Latin square design. Diets were either a control, where dietary forage consisted of a combination of corn silage, alfalfa hay, and prairie hay, or 1 of 2 teff diets, where teff hay was the sole forage. The teff diets maintained yields of milk and milk fat while increasing milk protein yield. Together, these two studies suggest that teff-based diets have potential to maintain high levels of milk production while improving the resilience of the dairy industry to future water shortages.

Doctor of Philosophy / Department of Animal Sciences and Industry / Timothy G. Rozell / Dairy cows require a low-stress environment in order to efficiently produce milk, and thus stress management is a common focal point for both researchers and producers. A primary source of stress for dairy cattle is associated with the environment, particularly heat, and therefore a considerable amount of research has been done in an attempt to find ways of reducing heat stress. Most of the research, however, has focused on using heat abatement techniques to cool the cow, using evaporative cooling systems to reduce temperature in the environment thus also cooling the cow, and selective breeding to improve thermal tolerance. Whereas cow comfort has been improved, there are still negative responses to heat stress today including decreased milk production and altered milk composition. Cattle remove excess body heat primarily through evaporative and convective cooling in the respiratory system and exercise is likely to improve blood flow and efficiency of heat transfer within the lungs. Furthermore, exercise has been proven to improve performance in humans and horses. This study was designed to determine whether or not exercise improved fitness and heat tolerance, and to observe whether there were any resulting effects on milk production and parturition. Two experiments were carried out during the late summer/early fall of 2014 and summer of 2015. Each experiment utilized a different exercise regimen: experiment 1 used a combination of high-intensity intervals and endurance training, whereas experiment 2 involved an endurance regimen performed during the afternoon in early summer. Pregnant Holstein heifers (Experiment 1, n = 24; Experiment 2, n = 24) were exercised in an 8-panel motorized walker over a period of 8 wk that ended approximately 21 d prior to parturition. In experiment 1, fitness was improved in heifers that were exercised compared with their non-exercised counterparts based on their duration of exercise and speed of exercise at failure (P < 0.05). During a cool hour of the day after 6 wk of exercise, exercised heifers spent more time in body temperature zone 1 (< 39.0°C) compared with their non-exercised counterparts (P < 0.05). Exercised heifers also spent less time (P < 0.05) than non-exercised heifers in body temperature zone 3 (> 40.0°C) during the hottest hour of a hot day during the 6th week. No treatment effects (P > 0.10) were found for weekly milk components or milk production. In experiment 2, exercise resulted in greater milk protein and solids-not-fat (SNF) percentage (P < 0.05) compared with contemporaries that did not exercise; however, there was no difference in weekly milk production during the first 150 days (P > 0.10). Fat-corrected milk and energy-corrected milk were calculated and no difference was detected between treatments (P > 0.10). These results are the first to show that high-intensity intervals and endurance training exercise in pregnant dairy heifers can improve heat tolerance, increase production of milk protein and SNF, and perhaps increase animal comfort and well-being during hot weather.

No description available.

This project has investigated the mechanism of caking of lactose and identified some possible solutions to minimise caking of lactose and dairy powders, additional to those suggested in the literature. A background to lactose and caking is given. The problems of caking are identified and discussed. The project adds information to the knowledge on the polymorphic forms of lactose and their inter-relationships due to moisture sorption and processes such as milling. This information and many others in the literature are used to complete the simplified lactose conversion diagram developed by King [1965] and improved by Walstra, et al. [1999], which has been widely used in the literature as a guide for lactose manufacturing, processing, and storage. / Doctor of Philosophy (PhD)