Doctor of Philosophy / Department of Animal Sciences and Industry / James S. Drouillard / Two trials were conducted to evaluate the effects of crude glycerin in feedlot cattle. The objectives of this research were to determine the effects of crude glycerin on animal performance, carcass characteristics, ruminal metabolism, and diet digestibility when fed in steam-flaked corn finishing diets. Trial one utilized crossbred heifers (n = 373) fed finishing diets containing 0, 2, 4, 8, 12, or 16% crude glycerin. Feeding heifers crude glycerin at 8% or less of the diet resulted in improvements in body weight gain and feed efficiency. Dry matter intake decreased linearly (P < 0.001) when glycerin was included at increasing levels from 0 to 16%. Average daily gains of heifers fed crude glycerin increased when glycerin was fed at 2, 4, or 8% of diet DM, but reductions in ADG were noted when glycerin increased to 12 or 16% (linear, P = 0.013; quadratic, P = 0.010). Feeding glycerin had a quadratic effect on G:F, and was optimal when fed at 2% of DM (P = 0.46). Hot carcass weights increased when glycerin was fed at 2, 4, and 8% of the diet, but decreases in HCW were observed with 12 and 16% crude glycerin (linear, P = 0.009; quadratic, P = 0.006). Low concentrations of glycerin can be fed without negatively impacting animal performances. Trial two consisted of a 3 × 3 Latin Square and utilized cannulated crossbred steers (n = 9) fed finishing diets containing 0, 2, or 4% crude glycerin. Apparent total tract digestibilities of DM, OM, starch, CP, and crude fat were unaffected by the addition of glycerin at 0, 2, or 4% of cannulated steer diets (linear, P > 0.51). Apparent total tract digestibilities of NDF tended to decrease as glycerin concentrations increased to 2 and 4% (linear, P <0.13). Ruminal pH increased as glycerin concentrations increased (linear, P < 0.05), and concentrations of butyrate and valerate decreased (linear, P < 0.03). Acetate production also tended to decrease when glycerin increased from 0 to 2 or 4% of the diet (linear, P =0.06). Collectively, these results suggest that glycerin may negatively influence fiber digestion.

Studies were conducted to determine the conditions in which alterations in cholesterol and lipoprotein metabolism can be induced by copper deficiency in male and female hamsters. Three week old animals were placed on either a copper-deficient or copper-adequate diet. The hematocrit and hepatic copper content were significantly reduced in the treatment animals, and the plasma volume was enlarged. These changes, however, were small in comparison to the findings of previous studies using copper-deficient rats. The hamsters, therefore, appeared to be only marginally deficient. There was no treatment effect on the composition of the lipoprotein fractions, except for decreases in HDL protein concentration and pool size in the plasma of females fed the copper-deficient diet. It was concluded that the copper status of the treatment animals was not sufficiently diminished to affect lipoprotein profiles and plasma cholesterol, and that dietary treatment should begin earlier than the third week of age.

Two experiments using lambs were conducted to obtain additional information on the potential nutritional value of halophyte forages for ruminants. In experiment one, Salicornia bigevolii Torr. planted in mid-March and harvested at three dates (July, August and September) replaced wheat straw (30%) in a 65% forage diet. Nutrient composition and digestibility of Salicornia forage declined with advancing maturity. Forage from the July cutting was superior to wheat straw, while that from later cuttings was approximately equal to straw. In experiment two, digestion coefficients were lower when Atriplex deserticola replaced 50% of the alfalfa hay in a 70% roughage diet. Even when all of the alfalfa hay was replaced using a mixture of 85% Atriplex barclayana and 15% Atriplex deserticola consumption by lambs was not adversely affected. It is concluded that Salicornia bigevolii and Atriplex deserticola have potential as feedstuff for ruminants, especially in geographical areas where conventional feedstuffs are not available.

No description available.

Tannins are polyphenolic compounds which precipitate, or conjugate, with proteins to make them indigestible. Tannins appear to confer anti-herbivore defense in shrub live oak (Quercus turbinella), a common browse in the interior chaparral of Central Arizona. The results of the present study indicate that the rumen microflora in goats can adapt to tannin rich diets thereby increasing in vitro dry matter digestibility of shrub live oak leaves. Major digestion inhibitors of shrub live oak appear to be fiber content (NDF, ADF, and lignin) and presence of condensed tannins in the leaves. In vitro dry matter digestibility of oak leaves appears to be higher in rumen microflora from goats than in rumen microflora from cows, although further research is needed to determine digestive efficiency among these species.

Effects of weaning on metabolic profiles and hepatic IGF-1 mRNA of beef dams (Trial 1), and diet effects for early-weaned (EW) steers on response to an infectious bovine herpesvirus-1 (BHV-1) challenge (Trial 2) were investigated. Trial 1 treatments were arranged in a 2 x 2 factorial and included 14 heifers and 14 cows assigned randomly to one of two treatment regimens: EW (average age of 114 ± 13 d) or normal-weaned (NW, average age of 197 d). Heifers with calves EW experienced a greater increase (parity x weaning; P = 0.02) in BW over heifers with calves NW, but no change in BW due to weaning was observed for cows (P > 0.71). Early weaning (vs. NW) increased (P < 0.05) body condition (BC) and change in BC of all dams. No parity x weaning or parity x weaning x d interactions (P > 0.14) were observed for serum IGF-1, NEFA, or urea nitrogen (SUN). A parity x d interaction (P < 0.05) for hepatic IGF-1 mRNA, serum IGF-1, and SUN was observed, but no differences (P > 0.10) were detected between heifers and cows within d. For Trial 2, backgrounding treatments included a bermudagrass hay diet (CTRL); bermudagrass hay plus soybean meal (SBM) fed at 0.175% of BW (as-fed); bermudagrass hay plus SBM at 0.35% of BW; or a 70% concentrate (CONC) diet. During the receiving phase, all steers were fed CONC and intranasally challenged with BHV-1. Treatment x d interactions (P < 0.01) were observed for serum NEFA, total protein, SUN, glucose, immunoglobulin G (IgG), insulin, and rectal temperature. Three d after the BHV-1 challenge, IgG was greater (P < 0.05) for forage-fed steers vs. CONC. Three and 4 d after the challenge, rectal temperature was greater (P < 0.01) for protein supplemented steers vs. CTRL. Therefore, EW can increase BW and BC of first-calf heifers and decrease SUN in first-calf heifers and mature cows, and a higher quality diet fed to EW steers during a backgrounding phase enhances ADG and G:F, and increases febrile response (measured by rectal temperature) to an infectious BHV-1 respiratory challenge.

Objectives were to determine the effects of feeding dry-rolled (DR) vs steam-flaked (SF) sorghum grain and degree of processing (flake density, FD) of corn and sorghum grain on site and extent of starch digestion and post-absorptive metabolism of energy-yielding nutrients in steers fed 77% grain. The design for each trial was a randomized block. Seven steers (400 kg) with duodenal and ileal cannulas were used to determine corn and sorghum starch digestibilities (Cr ratio, 3-d collection). Steers fed SF versus DR sorghum increased starch digestibility in the rumen (23%; P < .01), total tract (2.3%; P < .01), and in the small intestine (6%; P < .01, as percentage of starch entering duodenum). Decreasing flake density of SF sorghum grain increased linearly (P < .05) starch digestion (percentage of intake) in the rumen and total tract, and diminished linearly (P < .05) starch digestibilities post-ruminally and in the small intestine. Similar responses in starch digestibilities occurred by lowering FD of SF corn. Percent dietary corn or sorghum starch digestibility in the large intestine was less than 2% of intake. Feeding SF compared to DR sorghum did not alter net absorption and uptake or release of energy-yielding nutrient across SPL tissues. As expected, net absorption of glucose across portal-drained viscera (PDV) was negative (-.60 mol/d). Incrementally decreasing FD of SF sorghum linearly increased net PDV absorption of lactate (P =.04), glucose synthesis by the liver (P =.03), and SPL output of glucose (P < .01) and L-lactate (P =.03). Net propionate PDV absorption (P =.18), hepatic uptake (P =.21), and SPL output (P =.15) tended to be increased with lower FD. Increasing degree of grain processing, by incrementally decreasing FD, linearly increased ruminal and total tract starch digestibilities and net absorption of glucose precursors (propionate and L-lactate), resulting in increased hepatic synthesis and greater output of glucose from the gut and liver to the rest of the body. Based on these changes, the optimum FD for SF sorghum grain was 283 g/L (SF22).

Two experiments were conducted to determine the effects of grain processing, grain sources, protein sources, and bST treatments on lactation performance, ovarian activity and nutrient digestion in early lactation dairy cows. In experiment 1, forty-eight dairy cows were divided into six groups and fed diets containing 37 to 39% grain as either steam-flaked sorghum (SFS, 360 g/L), steam-flaked corn (SFC, 360 g/L), or steam-rolled corn (SRC, 490 g/L) with one of two protein sources, soybean meal (SBM) or Prolak® for 70 days. Main effects for grain and protein source were not different for DMI, milk yield, 3.5% FCM yield or feed efficiency. Although efficiency of feed conversion into FCM did not differ among treatments, cows fed Prolak® required 10% less NEL for every Mcal of NEL converted into body weight or FCM. Milk protein yield was increased by both flaked gain and Prolak®. Feeding flaked grain increased milk production by 1.5 kg/d compared with rolled grain. Increasing the ratio of RDS/RDP to more than 2.4 increased milk yield by 2.7 kg/d (39.0 vs 36.3 kg/d). Plasma NEFA levels did not differ among treatments and grain and protein source had variable effects on PUN. Compared with other grains, SFC increased digestibilities of DM and OM, and flaked grains increased digestibility of starch. Cows fed SFS had the lowest crude protein digestibility, but was highest in NDF. In experiment 2, thirty-two postpartum (5 DIM)Holstein cows were assigned to one of four treatments in a 2 x 2 factorial design for 90 days. Treatments were: steam-flaked sorghum diet with bST (SFS-B); steam-flaked sorghum diet without bST (SFS-N); steam-rolled corn diet with bST (SRC-B); and steam-rolled corn diet without bST (SRC-N). Cows receiving bST during the first 45 days of treatment had lower DMI and DMI as % of BW. Milk yield was increased by bST 3.1 kg/d and 1.8 kg/d during the 45 d and 90 d periods, respectively, resulting in greater feed efficiency for bST-treated cows. Grain processing did not affect DMI, milk yield and FCM yield. Neither composition nor yields of milk components were influenced by treatments. Compared to the SRC diet, SFS increased plasma glucose 5% and plasma insulin 19%. Grain processing and bST had no effect on either BHBA or hepatic triglycerides. PUN was reduced by bST, but NEFA was increased. Compared with SRC, SFS increased progesterone during the first two postpartum estrous cycles and cows receiving bST had significantly larger CL. Flaked sorghum compared with SRC increased digestibility of DM, OM, and starch, and neither grain affected digestibilities of CP, NDF or ADF. Treatments with bST did not affect any nutrient digestibilities.

Three experiments were conducted to determine the effects of bST on lactational performance throughout several stages of lactation, emphasizing advanced lactation and summer heat stress conditions. In the first experiment, a preliminary trial was conducted using seven Holstein cows averaging 424 DIM. Injections of bST increased milk, fat and protein yields, but did not affect milk composition. In the second trial, 24 cows in advanced lactation (292 DIM) with breeding problems were assigned to one of the three treatments in a randomized block design. Treatments were: (1) CON; low energy diet, without bST injection; (2) LED; low energy diet, injected with bST; and (3) HED; high energy diet, injected with bST. Cows showed a large response to bST in yields of milk, FCM, fat and protein, as well as on efficiency of feed conversion to milk. Energy density in the diet of cows receiving bST did not significantly affect any measured variable. In the second experiment, 76 lactating Holstein cows were distributed in three trials according to stage of lactation. Six intervals of DIM were considered: very early, early, mid, late, advanced, and extended lactations. A favorable response in milk yield to bST injections was observed in mid, late, advanced and extended lactations, while only a tendency was observed in early, but not in very early lactation cows. In the third experiment, 32 Holstein cows averaging 195 DIM were placed on four treatments to determine the effect of bST and evaporative cooling on lactational performance during summer heat stress. Milk yield was significantly increased by bST injections and tended to be higher for cooled cows. Fat and protein yields were increased by bST, but not by cooling. Non-esterified fatty acids in blood serum were higher in cows injected with bST, suggesting greater fat mobilization to support the increased milk production. Rectal temperatures and respiration rates were decreased by evaporative cooling, but not affected by bST injections.

To evaluate the effect of two different cooling systems on production, physiological, and hormonal responses, 37 Holstein and 26 Brown Swiss dairy cows were allotted to three treatments. A control group of cows had access to only shade (C). A second group was cooled with spray and fan (S/F) and the third group was under an evaporative cooling system called Korral Kool&circR; (KK). The trial lasted from May to September with a daily maximum temperature-humidity index from 73 to 85. Milk production differences in Holstein cows were significantly increased by KK and S/F. No treatment differences in milk production were observed in Brown Swiss cows. Protein percentages were higher in C group compared to Korral Kool group only in Brown Swiss cows, while fat percentage were similar among treatments in Holstein cows. Rectal temperatures and respiration rates of the C group were higher than S/F and KK in both Holstein and Brown Swiss cows. Triiodothyronine levels in milk were significantly higher in KK group compared to S/F and C groups, while cortisol levels were lower in C group than S/F and KK. Similar differences were observed in body weight and body condition score changes between treatments in Holstein or Brown Swiss cows. Pregnancy rate was increased in the groups under the cooling systems in Holstein cows, however this effect was not observed in Brown Swiss cows where C group had a higher pregnancy rate than cooled groups. The cows under cooling systems spend more time eating and outside of the shade in the early afternoon (12:00 to 15:00) than control group. Cows injected with bST (bovine somatotropin) increased milk yield significantly only in Brown Swiss cows, whereas respiration rates were increased in both breeds by bST but rectal temperatures were similar between bST and non-bST cows. These results demonstrate that both cooling systems are an alternative to increase productive and reproductive performance and comfort of Holstein cows during summer in hot-dry climates. The physiological responses of Brown Swiss cows indicated a better adaptation to a hot climate, however their milk production was lower than in Holstein cows.