Beef Research News
Brought to you by Kansas State University College of Veterinary Medicine - Farm Animal Section
Cattle transportation by commercial truck carrier is common in the United States, and often cattle are placed within 1 of 8 potential compartments within the truck for the journey. The objective of this research was to determine potential associations between animal wellness (as measured by ADG and health outcomes) during a relatively short backgrounding phase (46.6 ± 8.5 d) and location within the truck during transit. Data from 21 loads (average calves per load = 101.5; average BW = 210.1 ± 19.4 kg) were included in the analysis. For each shipment, calves were divided among 8 compartments within the trailer: nose on top deck (NOT), nose on bottom deck (NOB), bottom deck middle forward (BDF), bottom deck middle rear (BDR), rear on the bottom (ROB), top deck middle forward (TDF), top deck middle rear (TDR), and rear on the top deck (ROT). General logistic (health outcomes) and mixed (ADG) models were employed to analyze the data accounting for effects due to truck section as well as the hierarchical data structure of multiple arrival times, loads, and pens. Cattle in the ROT section had lower short-term gains compared to NOT and tended (P < 0.10) to be lower than NOB. Cattle in the forward sections (NOT, NOB) were less (P = 0.02) likely (odds ratio [OR]: 0.67, 95% confidence limits [CL]: 0.50, 0.94) to be treated at least once compared to cattle in the middle sections (TDF, TDR, TOP, BDF, BDR, BOT). Calves in compartments with 15 head or less tended (P < 0.10) to have lower odds of being treated compared with cattle in compartments with 16 to 30 head (OR: 0.79, 95% CL: 0.60, 1.0) or greater than 31 head (OR: 0.73, 95% CL: 0.53, 1.0). Our current project reveals that the location within the truck may impact calf health and performance.
B. J. White, D. Blasi, L. C. Vogel, and M. Epp. Associations of beef calf wellness and weight gain with internal location in a truck during transportation. Published online first on August 28, 2009. J. Anim Sci. 1910. doi:10.2527/jas.2009-2069
Early weaning alters acute phase reaction to endotoxin challenge in beef calves
Previous research indicates that early weaning prior to shipment can reduce transportation-induced increases in acute phase proteins (APP), and can increase feedlot performance in beef calves. These data suggest that the combination of weaning and transport stress may compromise the immune system of calves, thus hindering subsequent performance and health. Therefore, our objective was to determine if the innate immune response of early-weaned calves (EW; 80 d of age) differed from normal-weaned calves (NW; 250 d of age) in response to an endotoxin challenge. Eighteen Brahman x Angus calves (8 and 10 EW and NW, respectively; 233 ± 5 kg BW) were used. Calves were maintained on pasture with supplement and then moved into individual pens for 1 wk of acclimation prior to the start of the study. Calves were fitted with an indwelling jugular catheter 1 d prior to LPS challenge (0 h; 1.0 µg/kg BW, i.v.). Blood samples were collected at 30-min intervals from -2 to 8 h. Serum samples were stored at -80 0C until analyzed for cortisol, tumor necrosis factor-alpha (TNF), interleukin-1 beta (IL-1), IL-6, interferon-gamma (IFN), ceruloplasmin, and haptoglobin. While LPS increased serum cortisol (P 0.001) no weaning age effect (P 0.15) was observed. A weaning age x time interaction (P 0.04) was observed for TNF, IL-1, IL-6 and ceruloplasmin such that concentrations of these indices were greater in the NW compared with EW calves. For haptoglobin, a weaning age effect (P 0.03) was observed with NW calves having greater average haptoglobin concentrations compared to EW calves. Interestingly, the weaning age x time interaction (P 0.001) for IFN revealed greater IFN in EW compared with NW calves. Based upon these data, the innate immune system of EW calves appears to be more competent in responding to immune challenge compared to that of NW calves. Additionally, the differential IFN response indicates that the immune system of EW calves may be more effective at recognizing and eliminating endotoxin. These data suggest that an altered innate immune system may be one of the factors responsible for the improved feedlot performance previously reported in EW calves.
J. A. Carroll, J. D. Arthington, and C. C. Chase, Jr. Early weaning alters the acute phase reaction to an endotoxin challenge in beef calves. Published online first on August 28, 2009. J. Anim Sci. 1910.
Growth rate effect on feedlot performance, meat and carcass quality in beef steers
Eighty Angus and Angus x Simmental steer calves were used in a completely random design to determine the effect of rate of gain during the backgrounding period on subsequent feedlot performance, carcass characteristics, WBSF, and sensory analysis. Animals were stratified by body weight and allotted randomly to 1 of 10 pens (5 pens/treatment). Dietary treatments were formulated for an ADG of 0.91 kg/d (LG; 1.06 Mcal NEg/kg) diets and 1.25 kg/d (HG; 1.19 Mcal NEg/kg). Steers were fed 70 d during the growing period. The low gain diet consisted of 52.5% barley silage, 39.0% whole shell corn, and 8.5 % supplement, while the HG diet contained 43.9% barley silage, 47.4% whole shell corn, and 8.7% supplement (DM basis). Initial body weight (226 kg) was not different (P = 0.70) between treatments. Steers fed the HG diet had increased ADG (1.67 vs. 1.40 kg/d; P < 0.001) compared to steers fed LG diet. Dry matter intake was greater (9.49 vs. 8.35 kg/d; P < 0.001) for steers fed the HG vs. LG diet. Total backgrounding cost ($/hd) was lower (P < 0.001) for those steers fed LG diet compared to HG diet ($126.00 vs $140.35, respectively); however, total cost per kg of gain was not different (P = 0.24; $0.485/kg gain). Following the backgrounding period, steers were fed a common finishing diet for 135 d. During the finishing period, LG steers had similar (P = 0.12) (10.73 vs. 10.35 kg/d) DMI compared with those fed HG diets; however, ADG was not different (1.55 kg; P = 0.72) among treatments. Hot carcass weight, marbling score, 12th rib fat, LM area, and USDA yield grade were not different (P > 0.12) between treatments and averaged 363 kg, Sm30, 1.33 cm, 83.8 cm2, and 2.7, respectively. There were no differences (P = 0.77; 3.63 ± 0.12 kg) in Warner-Bratzler shear force tenderness of rib-eye steaks. Percent cooking loss was increased in LG diets (P = 0.017). No differences were observed in consumer sensory analysis of tenderness, juiciness, and flavor intensity (P 0.276; 5.43 ± 0.12, 5.07 ± 0.13, and 5.17 ± 0.05, respectively). These data suggest that feeding steers diets which differ in energy concentration and result in gains of 1.4 and 1.7 kg/d during the growing period results in minimal changes in subsequent finishing performance, and does not affect meat quality.
B. A. Loken, R.J. Maddock, M. M. Stamm, C. S. Schauer, I. Rush, S. Quinn, and G. P. Lardy. Growing rate of gain on subsequent feedlot performance, meat and carcass quality of beef steers. Published online first on August 28, 2009. J. Anim Sci. 1910. doi:10.2527/jas.2009-1853.
Comparison of CIDR protocols to synchronize estrus in beef heifers
The objective of the experiment was to examine the necessity of adding a GnRH injection to a 14 d controlled internal drug release (CIDR)-based protocol for synchronization of estrus in beef heifers that were prepubertal or estrous-cycling at the initiation of treatment. The hypothesis tested was that the addition of GnRH in a CIDR-based estrus synchronization protocol will increase the synchrony of estrus after PGF2 (PG). Beef heifers (n = 285) were assigned to 1 of 2 treatments within reproductive tract scores (2 or 3 = prepubertal; 4 or 5 = estrous-cycling) by age and BW. Heifers assigned to CIDR Select received a CIDR insert (1.38 g progesterone) from d 0 to 14 followed by GnRH (100 µg, i.m.) on d 23 and PG (25 mg i.m.) on d 30. Heifers assigned to CIDR-PG received a CIDR insert from d 0 to 14 and PG on d 30. Heifers were fitted with a HeatWatch estrus detection system transmitter at the time of PG administration for continuous estrus detection during the synchronized period (0 to 144 h after PG); AI was performed 12 h after estrus onset. Estrous response did not differ (P = 0.43) between treatments (94% CIDR Select, 98% CIDR-PG). Mean interval to estrus after PG was 7 h shorter (P = 0.01) and variance for interval to estrus was reduced (P < 0.01) among CIDR-PG compared to CIDR Select treated heifers. Conception rate to AI tended (P = 0.09) to be greater for CIDR-PG heifers (67%) compared to CIDR Select heifers (58%), and AI pregnancy rate was greater (P = 0.05) for CIDR-PG heifers (66%) compared to CIDR Select heifers (55%). Final pregnancy rate at the end of the breeding season was similar for the 2 treatments (81% for both; P = 0.94). We conclude that the administration of GnRH 9 d following CIDR removal in the CIDR Select protocol is not required to facilitate an improvement in the synchrony of estrus in beef heifers.
N. R. Leitman, D. C. Busch, D. J. Wilson, D. A. Mallory, M. R. Ellersieck, M. F. Smith and D. J. Patterson. Comparison of controlled internal drug release insert-based protocols to synchronize estrus in prepubertal and estrous-cycling beef heifers. Published online first on August 28, 2009. J. Anim Sci. 1910. doi:10.2527/jas.2009-2250
Evaporative cooling in heat stress relief of cattle
Evaporative cooling of ambient air (EC) is a main path for heat stress relief in cattle kept in the shade of semi-confining structures. Evaporative cooling is particularly efficient in hot dry climates. We examined the potential of EC for heat stress relief in cattle in moderately warm and humid climates. The feasibility was examined by the reduction in ambient temperature (Tac) produced by EC as a function of ambient temperature (Ta) and humidity (RHa). A data set (n = 139) of temperature and relative humidity (RH) produced by EC over a range of air temperature (25 to 50°C) and humidity (10 to 70% RH) was analyzed by polynomial second order regressions. The analyses produced equations for the relations between ambient air temperature and ambient humidity and between respective conditions in air cooled by EC (Tc, RHc). Linear regressions were computed for a narrower temperature range (30 to 40°C). In all equations, R2 were >0.94 and regression terms were statistically significant. The Tac obtained by EC diminished by 0.3°C per °C rise in Ta, indicating a reduced efficiency of EC with rising Ta. The Tac obtained by EC also was markedly reduced by rising ambient humidity and increased by RHc. An attempt to sustain Tac at greater RHa by allowing a rise in RHc would only restore 2/3 of the reduction in Tac because the coefficient for the RHa effect on Tac is 1.5 larger than that of RHc. The Tac attained by EC partially depends on the humidity in the cooled environment. Elevated RHc may impede animal skin and respiratory evaporative heat loss and lead to moisture accumulation in bedding. If the upper desired limit for RHc is 70%, at RHa smaller than 45% (typical for hot-dry environments) the Tac is larger than 7.5°C, at RHa greater than 55% Tac is reduced to less than 5°C, and at RHa of 57.5 to 60% Tac is about 2.5°C. Coupling EC with forced air movement when Tac is small may partially assist in alleviation of heat stress by enhancing the smaller convective heat loss at ambient temperatures above 30°C. These indicate a limited role for EC in relief of heat stress in moderately warm and humid conditions when RHa is greater than 50 to 55%. Forced evaporation of water from the surface of the animal by sequential hair coat wetting coupled with forced air movement is an alternative little affected by ambient humidity.
A. Berman. Predicted limits for evaporative cooling in heat stress relief of cattle in warm conditions. J. Anim Sci. 2009. 87:3413-3417.