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The acceptability and digestibility of mixtures containing selected fats of animal, vegetable and blended sources were studied. Ten fat containing mixtures were fed to Saddlebred horses in cafeteria style palatability trials and ranked according to preference. Preference ranking of the fats from highest to lowest is as follows: corn oil, blend no. 1, cottonseed oil, inedible tallow and fancy bleached tallow. When the most preferred fats from each classification (animal, vegetable and blended) were offered in single mixture palatability trails, no significant difference was observed in consumption. In Digestion Experiment I three fats, corn oil, blend no. 3 and inedible tallow, were added to an alfalfa and grain diet at the 102 level. The apparent digestibility of fatty acids in corn oil when calculated by difference, was higher than an inedible tallow or blend no. 3. The apparent digestibility of energy in corn oil calculated by difference, was 95.4%. However, this value was not different from that of inedible tallow and blend no. 3. The addition and kind of fat did not affect the apparent digestibility of acid detergent fiber or apparent absorption of minerals. Blood serum levels of total fatty acids, calcium, inorganic phosphorus, magnesium and glucose were not affected by the addition of the fats. However, serum cholesterol levels were increased (P <.05) by addition of fat. In Digestion Experiment II, feeding four fats (corn oil, peanut oil, inedible tallow and blend no. 3) at two levels (7.5 and 152%) was studied. When the apparent digestibility of fatty acids in the diet was calculated by difference, the average values were higher for corn oil and peanut oil, but the differences were not significant. The true digestibility of fatty acids showed all fat sources and levels were digested similarly. The apparent digestibility of diet energy was increased by the addition of the fats. The energy of diets containing corn oil had higher (P <.05) digestibilities than those containing inedible tallow or blend no. 3. As in Experiment I, there was no difference in energy digestibility of the added fats when calculated by difference. There was no depression of calcium absorption due to kind or level of added fat. Apparent absorption of phosphorus was not affected by type of level of added fat. Apparent absorption of magnesium was higher (P <.05) for the basal diet and those diets containing blend no. 3. Blood serum levels of total fatty acids, calcium, inorganic phosphorus, magnesium, cholesterol and glucose were not affected by the addition or type of fat. / Ph. D.

Five studies were conducted to elucidate a possible mode of action of dietary organic acids in weanling pigs (n=536). The effect of feeding 1.5% fumaric or citric acid on growth performance, intestinal digesta pH, chloride ion concentration (Cl-), VFA profile and microflora populations was studied. In study 1, feeding citric acid improved ADG and feed conversion (F:G), whereas fumaric acid only numerically improved ADG and F:G. No significant dietary effect on intestinal pH, Cl- or VFA profile was observed. In study 2, feeding organic acids with and without a microbial supplement (Lactobacillus acidophilus) resulted in no interactive effects, but fumaric acid and the microbial supplement each improved ADG and F:G. In study 3, pigs fed organic acids were killed at -2, 0, 3, 7, 14 and 21 d postweaning. Organic acids had no significant effect on intestinal pH, Cl-, VFA profile or microflora populations. Postweaning age affected intestinal digesta measurements in these ways: pH decreased; VFA concentrations increased; lactobacillus decreased to d 3 postweaning; E. coli increased to d 7 postweaning; and clostridia decreased to d 21 postweaning. In study 4, pigs were fed organic acids and orally challenged with 10¹⁰ enterotoxigenic E. coli (0157:K88) (ETEC) at d 3, 7 and 14 postweaning. Organic acids had no measurable effect on intestinal pH, Cl- or VFA profile. ETEC challenge increased jejunum lactic acid concentration, lower colon VFA concentration and severity of scouring. Postweaning age affected these intestinal digesta measurements: cecum pH decreased; jejunum Cl- increased; jejunum lactobacillus count decreased; lower colon lactobacillus count increased; and E. coli count decreased in all intestinal sections. In study 5, pigs were fed organic acids and challenge with ETEC on d 3 postweaning. Organic acids had no significant effect on severity of scouring or protection against reduced growth performance from the ETEC challenge. The ETEC challenge resulted in an increased severity of scouring and a reduction in ADG of 20% and F:G of 19%. In summary, feeding organic acids generally improved weanling pig growth performance and had little effect on intestinal digesta measurements. Postweaning age did have an effect on intestinal digesta measurements. The primary mechanism of action of dietary organic acids does not seem to be the lowering of intestinal pH or modifications to the intestinal microflora, but may act as an additional energy source. / Ph. D.

A series of experiments was conducted to examine protein and energy utilization in growing and breeding turkeys, and to investigate the impact of body weight restriction on subsequent reproductive performance. In the first experiment, dietary self-selection of energy and protein and feed restriction were studied in growing turkeys. Body weight of males and females was significantly reduced by feed restriction. Protein efficiency was significantly lower in self-selecting males and females. Feed restriction significantly reduced the carcass yield of males, but not females. / Ph. D.

To assess the biotin needs of developing gilts and sows, female swine were fed corn-soybean meal diets supplemented with 0 (NB) or 220 ug (SB) d-biotin/kg diet in three growing-finishing trials and corn (C) or wheat-based (W) diets supplemented with 0 (NB) or 440 (SB) ug d-biotin/kg in a four-parity sow study. During the growing-finishing trials, feedlot performance, hair and soundness scores were unaffected by dietary treatment, however, SB elevated (P<.001) plasma biotin (PB) and reduced the number and frequency of various toe lesions. Conception rate and the weaning to estrus interval were improved (P<.05) with SB. No significant responses were noted in farrowing and lactation performance. There was a trend for SB to improve litter size in multiparous females. Feeding SB diets elevated (P<.001) the biotin content of sow plasma, liver and milk, while sow hepatic pyruvate carboxylase activity was unchanged. Fetal plasma biotin levels were high in pigs from NB females and were increased four-fold when dams received SB diets. Farrowing performance was reduced in W females; however, level of biotin x type of grain interactions were not present. The frequency (%) of females with heel cracks, heel-horn junction cracks and side-wall horn cracks was reduced (P<.01) when females were fed SB diets. Females fed SB diets had fewer (P<.001) total toe lesions, heel cracks, heel-horn junction cracks, side-wall horn cracks and white-line horn cracks (P<.03) compared with NB females. Level of biotin x age interactions (P<.05) indicated that SB was more effective in reducing toe lesions in multiparous females with most reductions occurring following the first parity. Supplemental biotin did not alter soundness scores (P>.10) but increased (P<.001) the number of hairs/cm² and improved (P<.001) hair scores. Toe location influenced toe size and lesion development with outside toes being larger and containing more lesions. Toe lesions and toe size were not correlated (P>.10) to soundness. The results of this study suggest that the development of toe lesions in swine can be reduced with biotin supplementation and improvements in reproductive performance may be attainable. / Doctor of Philosophy

The effects of genetic and social factors influencing ingestive behaviors, growth, livability, and dietary self-selection were investigated in three experiments. In Experiment I, ingestive behaviors, livability, and body weight were measured in lines of White Plymouth Rock chickens selected for high (HW) and low (LW) juvenile body weight reared in cages and floor pens as line-separate (S) and line-intermingled (I) flocks in three replicated trials. Body weights of Line HW chicks in cages, livability of Line LW chicks in cages, and ingestive behaviors of Line LW chicks in floor pens were higher in I than S flocks. Experiments II and III were designed to determine the ability of young chicks to discriminate among diets differing in amino acid content. In Experiment II, growth, feed intake, and feed preferences for diets varying in content of lysine, methionine, or tryptophan were measured in Line HW and a line of White Leghorns (HA) selected for high antibody response to sheep erythrocytes. Chicks were fed one of seven diets which were either balanced (Diet A), or slightly (1) or moderately (2) deficient in lysine (L), methionine (M), or tryptophan (T) for seven days. Chicks were then offered a choice between Diet A and the diet fed for seven days (3 to 10 days of age). Line HW chicks eventually showed a consistent preference for Diet A to all but Diet L1. For diet preference, interactions between time and diet were common in Line HW and the causes of these interactions were discussed. Line HA chicks preferred Diet A to M2, but otherwise did not choose between diets. Growth of Line HW chicks was reduced by feeding Diets L2, L1, and M2, but growth was not affected in Line HA. In Experiment III chicks from Lines HW, HA, and LW were provided a choice among diets with .85, .58, and .44 % methionine from one day of age. Line HW discriminated among diets with different methionine content from five days of age, but chicks did not make a consistent choice until after a period of deficiency. After a period of deficiency, Line HW chicks consistently chose the diet with .85 % methionine. Line HA chicks consumed more of the diet in slight excess of their methionine requirement and the reason for this is not clear. Line LW chicks did not discriminate among diets at any time during the trial. These results indicate that several factors interact to influence ingestive behaviors, growth, livability, and dietary self-selection in different genetic lines of chickens. / Master of Science

Eight pregnant mares were randomly allotted to receive 100 and 120% of the recommended digestible energy (DE) (NRC, 1978), respectively, for the last 90 d of gestation. During the first 30 d of lactation, all mares were fed the NRC (1978) recommendations for lactation. The 120% DE-fed mares had an advantage of .18 kg (P<. 03) ADG during the last 90 d of gestation. The length of gestation and foal birth weight were unaffected by treatment. During 30 d postpartum, 120% DE-fed mares lost .16 kg/d while 100% DE-fed mares gained .33 kg/d (P<.04). Postpartum mare ADG were supported by foal ADG, with foals on 120% DE-fed mares having gained .37 kg/d more (P<.06) than 100% DE foals. Pooled data for all mares showed that day to first postpartum ovulation and follicle size on the eighth day postpartum were negatively (r=-.80; P<.05) correlated. First estrus postpartum was negatively correlated (r=-.69; P<.01) to follicle size at the eighth day postpartum and was positively correlated (r=.91; P<.01) to the day of first postpartum ovulation. Serum progesterone (P₄) and luteinizing hormone (LH) values were obtained at 3 d intervals starting 3 wk prepartum through 30 d postpartum with daily values 1 wk pre- and postpartum. No treatment differences within period in hormone concentrations were seen. However, the curvilinear effects of day for LH concentration up to and including the fifth order (r²=.73) and the seventh order for P₄ concentrations (r²=.59) were highly significant (P<.01). All mares received 100 µg gonadotropin releasing hormone (GnRH) on d 6 postpartum. Seven of 8 mares exhibited an LH response (P<.01) within 6 h post-administration. The 120% DE-fed mares experienced an advantage of weight gain during gestation and their foals gained faster during 30 d postpartum. No treatment differences were found for pre- and postpartum hormone concentrations or for the responsiveness of the pituitary as determined by GnRH administration. / Master of Science

Thirty six: Holstein bull calves were assigned to a 3X3 factorial design with ration physical forms of chopped hay (CH), ground hay (GR) and all concentrate (CONC) and rumen degradable nitrogen (RDN) of 30, 45 and 60%. Metabolic body weight, liver weight and blood glucose were greatest in CONC-fed calves. Neither dry matter nor ash content of liver tissue was affected by either physical form or RDN. Within physical form, protein content was highest and fat lowest in livers of CH-fed caIves. Within RDN, livers of calves feel 30% RDN rations had lowest protein and highest fat content. RDN percent had no effect on carbon dioxide production. Livers from CONC-fed calves produced significantly· (P<.05) more carbon dioxide from [1⁻¹⁴C}propionate and [U⁻¹⁴C}lactate.Glucose production from propionate and lactate was greatest for CONC-fed and 60% RDN-fed calves, although significant only from lactate within physical form. Interaction between ration physical form and RDN makes interpretation of propionate data difficult. In 30% RDN-fed calves both lactate and propionate metabolism was similar for GR- and CONC-fed animals. At 45 and 60% RDN rations, CONC- and CH-fed calves had similar gluconeogenic rates from propionate but glucose from lactate was significantly greater in livers of CONC-fed calves compared to GR- and CH-feet animals. Ten lactating and five dry Holstein cows were liver biopsied at various stages of lactation (30,60,90,120,180 days postpartum and dry) and when fed two rations, control ( 18% CF) or high concentrate (HI CONC, 10.5% CF). Lactating cows at 30 and 60 days and dry cows were fed the control ration. After 60 days half the cows remained on the control ration and half the lactating cows were changed to the HI CONC ration. Milk fat percent was depressed in cows fed HI CONC ration. Milk fat percent was depressed in cows fed HI COCC ration. HI CONC cows consumed more dry matter and due to the higher energy content reached a positive energy balance before control cows. Rumen fluid volatile fatty acid production was not affected by stage of Lactation or ration fed. Both plasma glucose and plasma insulin nonsignificantly increased as lactation progressed. Liver tissue protein did not change over lactation but increased when HI CONC ration was fed. Stage of lactation affected (P<.0002) propionate metabolism to carbon dioxide with higher production at 120 days compared to 180 days. By ration, HI CONC cows' livers produced more carbon dioxide than control cows’ livers. Feeding the HI CONC ration significantly increased labelled glucose production. Increased production of both labeled carbon dioxide and glucose by liver from cows fed HI CONC ration was nonsignificant when based on liver protein content. Carbon dioxide/glucose ratio was similar for lactating (>60 days) and dry cows. Cows early in lactation (30 days) had significantly lower carbon dioxide/glucose ratios, indicating a higher glucose production. Ration and stage of lactation are important factors in ruminant metabolism.. Gluconeogenesis, a pathway especially important in ruminants, is affected by both factors. In calves and cows, concentrate rations increased glucose production. Ration RDN, studied in calves, affected lactate metabolism to glucose. The liver of lactating cows showed a greater response (increase in glucose production) to stage of lactation than ration fed demonstrating the importance of energy balance on ruminant metabolism. / Ph. D.