Thesis (M.S.)--Michigan State University. Dept. of Agricultural, Food, and Resource Economics, 2008. / Title from PDF t.p. (viewed on July 28, 2009) Includes bibliographical references (p. 105-108). Also issued in print.

Thesis (doctoral)--Humboldt-Universität zu Berlin, 2000. / Includes bibliographical references (p. 128-140).

Replacement heifer rearing is critical for the future of the dairy operation, especially to improve genetic merit and maintain herd size. A replacement heifer from the day she is born to the day she calves herself is generally a 2-year investment without potential income. A myriad of options exists on how to manage, fed, and ultimately raise replacement heifers. This study quantifies the costs associated with replacement heifer management decisions from birth to calving related to housing, labor, feed and health. The heifer rearing period can be broken into pre and post weaning sections to allow for more understanding the variation of these different biological time periods. Variation can influence the investment per day and breakdown of resources required from a dairy producer. Total heifer raising cost varied broadly across all management scenarios in our study, with feed and labor consistently representing over 60% of the total cost. After determining the true cost on an individual farm, or providing developed assumed cost for a change in management, producers can better manage current expenses and be more prepared for future investment.

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The overall objective of this thesis was to assess the effect of feed area design including feeding space availability, barrier type and stocking density, on the feeding behaviour of dairy cows. Feed intake in dairy cows is directly related to milk production, thus a good food supply is extremely important to the modern, high producing dairy cow. Intake is critical for improving milk production, health, body condition and the welfare of the animals. Feeding designs can have a major effect on behaviour and feed intake, therefore it is an important consideration when housing cattle and other livestock. The effect of altering the amount of space allowance available at the feed-face highlighted a significant effect on feeding patterns. As the space allowance increased the number of feeding bouts also increased (P<0.001) and length of bouts decreased (P<0.05). However, when provided with extra space at the feed-face, cows did not increase their feed intake as hypothesised, possibly as a result of the differences between individual animals being masked by an overall group effect. The number of aggressive interactions decreased as the space allowance increased (P<0.001) and furthermore, the number of times individuals were displaced from the feeding area also decreased as the space allowance increased (P<0.05). Subsequently, preference tests were used as a behavioural tool to determine how individual cows perceive their feeding environment with specific emphasis on understanding what difficulties low ranking animals face at the feed-face. Subordinate cows showed a significant preference for feeding alone rather than next to a dominant when they were offered high quality feed on both sides of a Y-maze test (P<0.001). When “asked” to trade-off between feed quality and proximity to a dominant cow, subordinate cows chose to feed alone on low quality food. A follow-on experiment using the same methodology was undertaken and aimed to identify the space allowances at which cows would not trade-off food quality. Four different space allowances were tested. At the two smaller space allowances, cows preferred to feed alone and for the two larger space allowances, cows had no significant preferences. The feed barrier has been shown to have a major effect on feeding and social behaviour of group housed dairy cows. A barrier design that provides some sort of separation between cows has also been shown to reduce competition. The aim of the final study was to determine if a feed barrier which obscured the cows’ visual field whilst feeding would increase vigilance behaviour and alter normal feeding behaviour, particularly for subordinates. Two different types of feed barrier were tested at four different stocking densities. The average daily feeding time was higher when cows were fed using a conventional headlock system compared to an electronic feeding system (P<0.05). All groups of cows displayed vigilance scans, however, neither type of barrier, feed space allowance, or dominance rank had an effect on the frequency of scans. These results indicate that neither feeder design nor stocking rate affect vigilance in dairy cows, at least over the treatment conditions assessed in the current study. The results of this research illustrate that to achieve the maximum levels of feeding behaviour and a reduction of aggressive behaviour, the cows’ environment must be such that it provides sufficient space and feed barrier design which will allow normal social behaviour. Over-stocking at the feed-face should be avoided to reduce competition. Future research should consider the long term effects of over stocking and competition on dry matter intake (DMI), milk production and health.

Heat stress abatement is a challenge for producers in the United States, especially in the southern states. Dairy producers could benefit by having a simply metric to measure heat stress abatement strategies with the goal of motivating improvement in heat stress management. Managing heat stress is key to ameliorating the effects on dairy cow performance. A study was performed to explore the use of a heat stress metric called the Summer to Winter performance ratio (S:W ratio), to quantify and compare farm performance variables among regions of the United States. Summer to Winter ratios were closest to 1.0 in the northern regions and furthest from 1.0 in the southern regions for all performance variables other than milk fat and protein percentage. This suggests that summer performance varies by region and shown using the S:W ratio. A second study compared S:W ratios among Southeast states and then applied the performance ratio to heat abatement strategies in Southeast states. The S:W ratio varied by performance measure and heat abatement strategies but tended to be best for herds implementing cow cooling strategies. The studies in this thesis demonstrated S:W ratios can identify heat stress differences by region and heat abatement strategies by herds.

The objective of this study was to evaluate two semen collection schedules utilizing the assumed behavioral differences between bovine species. The efficiency was measured by bull behavior and semen quality parameters. Four Holstein and four Brahman bulls were collected each during a morning and a night collection time weekly. Ejaculates (n=64) were obtained via artificial vagina over four-weeks. To avoid masking benefits of night collection, the first collection of the week was alternated between night and day. Two collection teams were employed to reduce the time needed for collection, and the variability in collection method. Sampling order and collection team were randomized throughout the study. Bull behavior parameters included reaction time to first mount, time to ejaculation, a refractory period test, and a thrust intensity test. As a managerial factor, the numbers of handler interruptions were counted. Pre-freeze semen parameters included total volume, initial motility and concentration. These were combined as total motile sperm harvested. Post-freeze semen viability parameters included post thaw motility, percent intact acrosomes, and 3-hour post thaw motility. Semen morphology parameters consisting of primary and secondary abnormalities were also measured. All data were analyzed by least squares methods. The bull within breed interaction was significant for all bull behavior parameters as well as the managerial parameter (P < .05). The bull within breed effect for total motile sperm harvested was not significant, but differed between breeds (P< .05). There was a mixed response due to bull within breed for the post freeze semen viability parameters. Bull within breed was not significant for the semen morphology parameters. The night versus day treatment was significant for the managerial parameter (P = .002). Consideration of a different collection schedule for Bos indicus cattle was not warranted. However, the efficiency of the collection process was impacted by extraneous environmental conditions.

There is a pronounced public awareness about herbal remedies. Garlic and ginger have antibacterial properties and prevent cardiovascular diseases. Onion and turmeric decrease the risk of diabetes and like garlic, they have anticancer properties. Streptococcus thermophilus, Lactobacillus bulgaricus and Lactobacillus acidophilus are lactic acid bacteria that produce lactase and reduce the symptoms of malabsorption. Earlier work has shown the influence of spice extracts but the influence of pure spice juice on yogurt culture bacteria is not known. Characteristics of yogurt culture bacteria were measured by suspending freshly thawed cultures in 0.1% peptone water (growth), acidified MRS broth (acid tolerance), MRS-Thio broth with oxgall (bile tolerance) and skim milk (protease activity) with 1% (v/v) of freshly extracted spice juice. Control samples had no spice juice. A probiotic blueberry yogurt was made with 0.05% of individual spice juice. Physico-chemical characteristics of the three bacterial cultures used were determined and a consumer acceptability test was conducted. Results show that these 4 spices did not have an inhibitory effect on the growth of the three culture bacteria. Turmeric improved the protease activity of L. bulgaricus and alongside with ginger, it also improved the protease activity of L. acidophilus. All four spices decreased the pH of the spicy yogurt. Coliform bacterial growth was significant on turmeric yogurt at day 1 of storage when compared to control and the other spices. Streptococcus thermophilus grew better in garlic and ginger yogurt, while L. bulgaricus grew better in onion and turmeric yogurt. Color measurements showed a decreased lightness (L*) from all spices, red color space values for the red-green axis (a*), turmeric in the yellow color space and the rest of the spices in the blue color space for the blue-yellow axis (b*). Apparent viscosity was higher in onion and ginger yogurt. The consumer testing showed a well acceptance of the control and ginger yogurt. Ginger had the highest intent of purchase by consumers. Ginger can be used in yogurts for direct consumption while all 4 spices have potential for a new product line of yogurts for cooking and dips, enabling potential health benefits from both sources.

Lactose sugar is a source of energy for Lactic Acid Bacteria (LAB) in dairy fermented products. Enrichment of yogurt with lactose addition may increase growth and viability of the yogurt starter culture (Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus) and enhance yogurt physico-chemical and sensory attributes. The objectives of this study were: to determine the influence of added lactose on (1) acid and bile tolerance of yogurt starter culture Streptococcus thermophilus ST-M5 and Lactobacillus bulgaricus LB-12, (2) the final lactose content of yogurt during its shelf life, (3) the physico-chemical characteristics of yogurt during shelf life, (4) the growth of the yogurt starter culture during yogurt´s shelf life and (5) the sensory attributes of yogurt. Acid tolerance test was conducted on pure culture at 30 minutes intervals for 2 hours of incubation period and bile tolerance at 1 hour intervals during 12 hours. Fat free plain set-type yogurt was manufactured using 0, 1, 3 and 5% w/w added lactose to accomplish objectives 2, 3 and 4. For objective 5, a blueberry yogurt was manufactured using the same lactose levels. Analyses for plain set-type yogurt were done at 7 days intervals during 35 days of storage period. Sensory evaluation was conducted on yogurt 3 days after its manufacture. Data were analyzed using Proc Mixed model of SAS® 9.3 program and by analysis of variance (ANOVA) using Proc GLM. Significant differences between means were analyzed at α = 0.05 using Tukey´s adjustment. Lactose had a positive effect on acid tolerance and bile tolerance of both yogurt starter cultures, growth of S. thermophilus and sensory attributes of flavored yogurt. Mean overall liking scores were higher for samples containing added lactose compared to control as tested by 100 panelists. Lactose supplementation in yogurt might be a good approach to increase its health benefits, acceptability and purchase intent among consumers.