Recipient Organization
UNIVERSITY OF CALIFORNIA, DAVIS
410 MRAK HALL
DAVIS,CA 95616-8671
Performing Department
Animal Science
Non Technical Summary
This project supports the mission of the Agricultural Experiment Station by addressing the Hatch Act area(s) of: plant and animal production, protection, and health.The practical significance of feedlot diet formulations to meet metabolizable protein requirements of calf-fed Holstein steers will be evaluated. Considering that methionine and lysine are first limiting amino acid during the initial growing period, two trials will be conducted that evaluate metabolizable methionine and lysine supplementation in feedlot diet formulations that are supplemented to meet or exceed expected requirements for metabolizable protein. Due to the prolonged nature of the feeding period, liver abscess can be elevated in calf-fed Holstein steers. Virginiamycin is an antibiotic approved for control of liver abscess. In this study we will also examin strategic supplementation of virginiamycin to determine feasibility of different supplementation periods to optimize the approach for abscess control. In a second trial treatment effects on metabolizable amino acid suppilmentation to estimate metabolizable amino acid supplies during differing phases of the growth-performance study.Becasue calf-fed Holstein steers are on feed for most of the year they will experience the effects of the elevated temperatures during late spring, summer and early fall months. We will evaluate 3 different essential oil-based feed additives that have been shown to reduce core body temperature in monogastics. Response to additives will be assessded in terms of cattle growth performance and as well as measures of ruminal pH, core body temperature, steer activity, panting, rumination, and water consumption.
Animal Health Component
80%
Research Effort Categories
Basic
20%
Applied
80%
Developmental
(N/A)
Goals / Objectives
The objective of this study is be to evaluate nutrition, management and health factors that will optimize growth-performance and carcass characteristics of calf-fed Holstein steers.The objective of the current experiments are: 1) Continue evaluation of the influence of metabolizable amino acid nutrition of calf-fed Holstein steers during the initial growing phase in the feedlot on overall feedlot growth performance and net energy value of the diet, Changes in growth performance and dietary net energy will be assessed with respect to characteristics of digestive function and estimates of amino acid supply to the small intestine; 2) evaluate antibiotic supplementation strategies for control of liver abscess; 3) evaluate strategies to reduce effects of elevated low desert ambient temperature on growth performance of Holstein steers; 4) examine the relationship among surface-skin temperature, body core temperature, respiration rate, physiological status, and the behavior of Holstein steers under heat stress and different feeding management strategies.
Project Methods
Two hundred Holstein steer calves (==127 kg) originating from Tulare, California will be shipped to the University of California Desert Research Center, Holtville. Upon arrival, calves will be vaccinated for IBR, BVD, PI3, and BRSV (Bovi-shield® Gold One Shot, Zoetis Animal Health, New York, NY), clostridials (Ultrabac® 7, Zoetis Animal Health, New York, NY), treated for parasites (Dectomax® Injectable, Zoetis Animal Health, New York, NY), and injected with 500,000 IU vitamin A (Vital EA-D, Stuart Products, Amarillo, TX). Steers will be balanced by weight and assigned to 40 pens (5 steers/pen). Steers will be fed a conventional steam flaked corn-based diet. Two levels of supplemental protected amino acids (0 vs 0.6% Smartamine ML; 55% L-lysine-HCI and 15% DL-Methionine coated with a pH-sensitive polymer, Adisseo, Alpharetta, GA) and four virginiamycin supplementation strategies will be evaluated in a 2 x 4 factorial arrangement of treatments. The amino acid treatments will be applied during the initial 168-d growing phase. The four supplemental virginiamycin treatments are: 1) 0 supplemental virginiamycin; 2) 16 mg/kg virginiamycin supplemented during the initial 168 d; 3) 16 mg/kg virginiamycin supplemented during the final 168 d; and 4) 16 mg/kg virginiamycin supplemented continuously for 336 days. Steers will be allowed ad libitum access to water and dietary treatments. Fresh feed will be provided twice daily. Hot carcass weights, liver scores and carcass measures will be obtained from all steers at time of slaughter. Energy gain (EG, Mcal/d) will be calculated by the equation: EG = ADG1.097 .0557W.75 (NRC, 1984). Maintenance energy (EM) will be calculated by the equation: EM = .084 W.75 . Calves will be weighed at 28-d intervals. From the derived estimates of energy required for maintenance and gain, the NEm and NEg values of the diet will be obtained by means of the quadratic formula: x = (-b - Ob2-4ac)/2c, where a = -0.41 EM, b = 0.877EM+ 0.41 DMI + EG, and c = -0.877DMI, and NEg = 0.877NEm - 0.41 (Zinn and Shen, 1998). For calculating steer performance, live weights will be reduced 4% to account for digestive tract fill. The trial will be analyzed as a randomized complete block design experiment.Four Holstein steers with cannulas in rumen and proximal duodenum (Zinn and Plascencia, 1993) will be used in a 4x4 Latin square design to evaluate characteristics of digestion of Basal Diet 1 (Table 1) supplemented with two levels of Smartamine ML (0 vs .6%) and two levels of virginiamycin (0 vs 16 mg/kg) in a 2 x 2 factorial arrangement. Chromic oxide (0.3%) will also be included as an indigestible marker to estimate nutrient flows and digestion. Chromic oxide will be premixed with minor ingredients (urea, limestone and trace mineral salt) before incorporation into complete mixed diets. Smartamine ML and virginiamycin will be top-dressed on feed at time of feeding. Steers will be housed (indoor facility) in individual pens (4 m2) with concrete floor covered with neoprene carpet, automatic waterers and individual feed bunk. Experimental diets will be fed daily in equal portions at 08:00 and 20:00 h. Dry matter intake was restricted to 2.2% of the body weight. Experimental periods consist of 10 d for diet adjustment and 4 d for sample collection. Feed, duodenal fluid and fecal samples will be subjected to the following analysis: DM (oven drying at 105 °C until no further weight loss method 930.15, AOAC, 2000); ash (method 942.05, AOAC, 2000), Kjeldahl N (method 984.13, AOAC, 2000); and chromic oxide (Hill and Anderson, 1958). Duodenal samples will be analyzed for ammonia N (method 941.04, AOAC, 2000), amino acid (method 982.30 E, AOAC, 2006), and purines (Zinn and Owens, 1986). Duodenal flow and fecal excretion of DM will be calculated based on marker ratio, using chromic oxide. Feed and duodenal samples will be analyzed for microbial organic matter (MOM) and N (MN) leaving the abomasum using purines as a microbial marker (Zinn and Owens, 1986). The trail will be analyzed as a 4x4 Latin square with 2x2 factoral arrangement of treatments,Two hundred Holstein steer calves (=127 kg) will be used to evaluate calf-fed Holstein steer responses to ambient conditions throughout the course of a 336-d feeding period. Receiving and management will be similar that that reported above. Calves will be balanced by weight and assigned to 40 pens (5 steers/pen). Steers will be fed a conventional steam flaked com-based diet. Three commercial essential oil-based supplements (Promote, Valido ICE, and Therma-Comfort) will be compared with the control diet (no heat stress additive). A subset of steers in each pen will be given a Smaxtec rumen bolus via a balling gun to measure pH, temperature, and activity. A subset, if not the whole group, will receive an SCR ear tag to measure activity, panting, rumination, and water consumption. Steers will be allowed ad libitum access to water and dietary treatments. Fresh feed will be provided twice daily. Hot carcass weights, liver scores and carcass measures will be obtained from all steers at time of slaughter. Energy gain (EG, Mcal/d) will be calculated by the equation: EG = ADG1 .097 .0557W. 75 (NRC, 1984). Maintenance energy (EM) will be calculated by the equation: EM = .084 W. 75 . Calves will be weighed at 28-d intervals. From the derived estimates of energy required for maintenance and gain, the NEm and NEg values of the diet will be obtained by means of the quadratic formula: x = (-b - Ob2-4ac)/2c, where a= -0.41 EM, b = 0.877EM + 0.41 DMI + EG, and c = -0.877DMI, and NEg = 0.877NEm - 0.41 (Zinn and Shen, 1998). For calculating steer performance, live weights will be reduced 4% to account for digestive tract fill. The trial will be analyzed as a randomized complete block design experiment.