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Biomedical subjects

R W Gardner

Publications and source records attributed to R W Gardner.

At least 19 recordsLinked to original sources
PubMed1990

Causes of adverse responses to soybean milk replacers in young calves.

Sixty Holstein bull calves were randomly assigned to one of three treatment groups following an initial 3-d colostrum feeding period. They were fed either whole cows' milk or ethanol-extracted or hexane-extracted soy flour in milk replacers to 6 wk of age. These products were used to identify possible causative factors associated with adverse responses to soybean in milk replacers. Average weight gains to 6 wk of age were 13.8, 7.3, and 2.8 kg and mortality was 0/20, 4/20, and 9/20 for calves fed milk, ethanol-extracted soy, and hexane-extracted soy, respectively. Heart rates (beats/min) were increased by the soy flours: 99.1 (ethanol extracted) and 116.3 (hexane extracted) versus 87.6 (milk). There was also an increased respiratory rate (breaths/min) with 67.6 and 61.1 versus 41.6 for the same treatment groups. Intradermal wheal growths verified an allergic sensitivity to the soybean products. Serum prostaglandin F2 alpha was 22% higher in the serum of calves fed the hexane-extracted soy milk replacer than in the serum of calves fed milk. Phenolic compounds in the soybean flour were implicated as possible causative factors in the adverse responses to the soybean milk replacers. Ethanol extraction of the soy flour was more effective than hexane extraction in removing phenolic compounds (2.19 vs. 1.00% phenolics).

Animal Feed↗
PubMed1988

Feeding and management of dairy heifers for optimal lifetime productivity.

A total of 433 Holstein heifer calves were fed two different energy amounts from 6 wk of age to breeding weight to determine the effect of early nutrition and age at first calving on lifetime performance. A control group of 182 heifers was fed according to the Beltsville growth standard. A second group of 251 heifers was accelerated in growth by providing more energy during early development. Both groups of heifers were bred at a minimum weight of 340 kg. Average ages at first calving for control and accelerated heifers were 24.6 mo and 22.2 mo with corresponding 305-d first lactation unadjusted milk production values of 6985 and 6729 kg and unadjusted milk fat yields of 222 and 216 kg. Average 305-d milk production values through subsequent lactations for control and accelerated animals, were lactation 2, 7790, 7842 kg; lactation 3, 8200, 8330 kg; lactation 4, 9481, 9134 kg; lactation 5, 9865, 9588 kg; lactation 6, 9515, 10,108; lactation 7, 9661, 10,112. Average total milk yields over five lactations were 42,321 and 41,623 kg. Percentages of cows remaining in the herd after five lactations were 19 and 18 for control and accelerated animals. Reproductive problems, mastitis, and deaths accounted for 70% of cows leaving the herd and did not differ between treatment groups.

Animal Husbandry↗
PubMed1984

Influences of methionine hydroxy analog on milk and milk fat production, blood serum lipids, and plasma amino acids.

Feeding for 150 days of 25 g per day of methionine hydroxy analog was tested on 100 cows (52 treated and 48 controls) in the Brigham Young University herd. Effect of days after parturition of initiating methionine hydroxy analog feeding also was observed. Milk yields were not affected by methionine hydroxy analog, but fat percent and fat yields were increased 21 and 17% by the additive. Abnormally low milk fat by control cows (2.84%) magnified the response to methionine hydroxy analog feeding. Feeding methionine hydroxy analog beginning 0 to 12 days postpartum elicited much larger increases of milk fat than started later (17 to 102 days). Blood from the coccygeal vein of 20 cows from each treatment had 10% more triglycerides from cows fed methionine hydroxy analog than from control cows. Increases of arterio-venous differences across the mammary gland of triglycerides and lipoproteins of blood serum suggested that increases of milk fat could have resulted from greater uptake of performed fat by the udder. Feeding methionine hydroxy analog increased methionine, isoleucine, and leucine in serum of coccygeal vein, but methionine was the only amino acid with significantly higher arteriovenous differences across the mammary gland.

Amino Acids↗
PubMed1981

Milk gases, mastitis and milking machines.

Recent studies both in the field and in research laboratories demonstrate that pressure changes within a milk machine system can cause bacteria-laden milk droplets to be introduced into the teat during milking. The injection of milk droplets into the teat cistern by pressure differentials across the teat orifice is dependent upon: dissolved gases in the milk, the level of vacuum, the time the teat is exposed to vacuum after the end point of milking, and the resistance of the teat wall to collapse in response to the internal vacuum space within the teat cistern after milking. Recent evidence using scanning electron microscopy, supported by field studies, demonstrates manufacturing problems of teat cup inflations as they relate to bacteriologic contamination in the environment of the teat. A new approach is needed in mastitis control research to include an independent agency for the evaluation of milking machines as they relate to tissue damage and microbial recontamination of the teat orifice.

Animals↗