The objective of this study was to evaluate digestibility of cubed hay as a feedstuff for ruminants. Angus (n=6), Hereford (n=3), and Charolais (n=3; total n=12; 226 ± 21.8kg) steers, stratified by breed, were randomly assigned to 3 treatment groups: 1) hay; 2) chopped; 3) cubed. There was no difference (P > 0.05) of DMI or digestibility of DM, OM, NDF, ADF, hemicellulose, and energy among treatments. Steers consuming hay digested more CP than those consuming chopped. Steers consuming cubed digested less CP than those consuming hay or chopped. More fat was digested by steers consuming hay or chopped than by those consuming cubed. Steers consuming cubed retained more nitrogen than those consuming chopped. Those consuming hay were intermediate. Nitrogen metabolized was greater for steers consuming hay than for steers consuming chopped. Those consuming cubed were intermediate. Steers consuming hay and cubed had greater metabolizable protein than those consuming chopped.

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The effect of feeding Zilpaterol hydrochloride (ZH) with a 3 or 10 d withdrawal (WD) period to calf-fed Holstein steers (N=2993) on carcass characteristics and tenderness were evaluated in a feed lot experiment. Cattle were fed 0 or 8.3 mg/kg of ZH for the final 20 d of the feeding period, each treatment level was assigned a WD period of either 3 or 10 d. Treatment groups consisted of Control 3 d WD (C3) and 10 d WD (C10), and ZH fed 3 day WD (Z3) and 10 d WD (Z10). Cattle were slaughtered at a commercial facility, carcasses chilled for at least 40 hours and carcass characteristics evaluated by trained personnel. Loins (n=60) were randomly selected from each treatment group for Warner Bratzler Shear (WBS) analysis. Rib-eye area (REA) increased 3.8 cm2 for ZH fed 3 day WD cattle (P<0.01) when compared to control, and 5.4 cm2 for ZH fed 10 day withdrawal cattle (P<0.01) when compared to control. There was no significant difference in REA between ZH fed 3 and 10 d WD periods (P>0.05). A trend was observed for ZH fed 10 d WD cattle to have an increased hot carcass weight when compared to control (P=0.0589), while there was no significant difference for cattle fed ZH with a 3 day WD (P=0.3763) comparatively. There was no difference in ZH fed cattle when compared to control on; kidney pelvic and heart fat %, adjusted preliminary yield grade, calculated yield grade, marbling score, or lean and bone maturity (P>0.05). There was an increase in WBS for ZH fed cattle when compared to control for Choice 7 d and 14 d aged steaks for both WD periods. Choice Z10 steaks aged 21 d showed an increase in WBS (P<0.05) while the Z3 had no effect. Select Z3 7 d aged steaks had higher WBS when compared to control while Z10 had no effect. Oppositely, the Select Z10 14 d aged steaks had increased WBS while the Z3 had no effect. There was no difference in Select 21 d aged steaks. There was no difference in WBS between the Z3 and Z10 for any of the aging periods. Feeding Zilpaterol hydrochloride for 20 d increased carcass leanness while having little effect on carcass fat of calf-fed Holstein steers. There was no difference observed between 3 d and 10 d WD period. Zilpaterol hydrochloride treatment decreased steak tenderness, although as aging progressed there little to no difference between steaks from ZH fed and control cattle.

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Recent efforts have improved synchronization systems that facilitate timed insemination in beef cattle. However, synchronization systems utilizing a single fixed-time artificial insemination (FTAI) frequently result in 25-40% non-pregnant heifers. The purpose of this study was to determine the effectiveness and define economic parameters of a FTAI resynchronization protocol in beef heifers after synchronization using a 5d CO-Synch + CIDR system. Estrus was synchronized in crossbred heifers (n=176) using 5 d CO-Synch + CIDR with FTAI at 72 h. After the initial AI, open heifers received either resynchronization (RS) or natural service (NS) return service treatments. The RS treatment was diagnosed for pregnancy 29 d after the initial AI, and all open heifers were resynchronized using the 5 d CO-Synch + CIDR with FTAI at 72 h. Heifers diagnosed pregnant following initial AI received no further treatment. Heifers in the NS treatment were exposed to fertile bulls from d 14 to d 66 following initial AI. Return to estrus data were collected using the Heat Watch Estrus Alert System. Total AI pregnancies tended to be higher (P=0.07) for RS (69.7%) than NS (56.5%) heifers. Overall pregnancy rate was greater for NS (89.4%) than for RS (69.7%) at the end of the breeding season (P < 0.01). The cost of RS was $128.63 and for NS was $82.50 per pregnancy. The expected average calf value per heifer exposed was $195.84 for RS treatment and $357.62 for NS treatment. This difference was attributed to the increased number of open heifers in the RS treatment. The resynchronization of estrus after the initial FTAI yielded a limited number of pregnancies in the breeding season in this study. However, the resynchronization program also cost more per pregnancy. Further investigation into resynchronization should focus on both biological and economic impacts. / Master of Science

A comparison of 2 basic methods presently used to transport perishable food samples intended for microbiological analysis is presented. A transport system using an appropriate, pre-chilled container with dry ice as the temperature contro11ant resulted in a significant1y higher (P ~ 0.01) survival rate of Clostridium perfringens vegetative cells in ground beef samples as compared to survivals in samples shipped in Trans Temp containers using canisters of a commercia11y formulated eutectic salts mixture as temperature contro1lant. Dry ice kept samples also resulted in greater recoveries of Staphylococcus aureus and the aerobic microf1ora~ Slightly higher recoveries of co1iforms and Escherichia coli were obtained from samples held by the Trans Temp procedure! Mixing samples 1:1 with 10, 20 or 30% (wt/vo1) buffered solutions of either dimethylsulfoxide or glycerol prior to freezing generally improved the survival of all microorganisms assayed regardless of the transport system tested. The results indicate that packaging perishable food samples with a volume of cryoprotective solute may be a useful adjunct to frozen transport systems thereby improving survival and allowing more complete recovery of selective micro-rganisms with existing assay procedures. / Master of Science

Overfeeding of phosphorus (P) is a contributing factor to P levels in surface waters. The objective of this study was to determine the impact of increasing levels of corn gluten feed (CGF) as a supplemental source of P on fecal P excretions. Eight Hereford steers (427±79 kg) were randomly assigned to one of four dietary treatments in a 4 x 4 replicated Latin square design. Steers were fed chopped grass hay ad libitum (0.13% P) and 0, 0.5, 1.0 or 1.5 kg/d of dried CGF pellets. All steers were supplemented with 0.91 kg/d beet pulp, 0.34 kg/d rumen-inert fat supplement and 18.14 g/d trace mineral salt. Urea was added to the respective diets at levels of 95.25, 72.57, 49.90, and 31.75 g/d to ensure equal dietary protein across treatments. Steers were housed individually and fitted with total fecal collection bags. Steers were adjusted to each diet for 9-d followed by a 5-d collection period. Following the final collection of each period, a 10 ml jugular blood sample was collected and analyzed to determine serum inorganic P. Dietary total P increased (P < 0.05) as CGF level increased: 8.72, 12.59, 16.75 and 20.88 g/d. Dry matter digestibility increased linearly (P < 0.05) as dietary P increased: 50.35, 53.66, 54.25 and 55.42%. Total P excretion increased linearly (P < 0.05) with increasing CGF level: 9.66, 11.71, 14.29, 16.96 g/day. Inorganic P excretion increased linearly (P < 0.05) with increasing CGF level: 4.11, 5.93, 8.36 and 9.92 g/day. Total P excretion was highly related (P < 0.05; r2 = 0.79) to inorganic P excretion. Serum inorganic P increased linearly (P < 0.05) with increasing dietary P content: 5.61, 5.87, 6.64 and 6.80 mg/dL. Fecal P increased as CGF level increased in steers fed varying dietary levels of P from plant sources. Management of P intake can be a strategic practice to reduce P fecal excretions in beef cattle. / Master of Science