LAB 93656

Cattle grazing in the shade.

INVESTIGATOR: Franke, D. E.; Wyatt, W. E.; DeRouen, S. M.; Miller, J. E.

PERFORMING INSTITUTION:
ANIMAL SCIENCE
LOUISIANA STATE UNIVERSITY
BATON ROUGE, LOUISIANA 70893

GENETIC (CO)VARIANCE OF PARASITE RESISTANCE, TEMPERAMENT, AND PRODUCTION TRAITS OF TRADITIONAL AND NON-BOS INDICUS TROPICALLY ADAPTED BREED

NON-TECHNICAL SUMMARY: Brahman crossbred cattle have been the predominant breed type in the Southern US because of their adaptation to tropical and subtropical climates and tolerance to internal parasites. Other tropically adapted breeds are being evaluated because of undesirable carcass attributes of Brahman crossbred steers. This project examines breed and heterosis effects of non-Bos indicus tropically adapted breeds for measures of fertility, growth, carcass, parasite resistance, and temperament traits in subtropical and temperate regions of the US.

OBJECTIVES: 2. Characterize diverse, tropically adapted beef breeds in subtropical and temperate areas of the United States. 3. Determine genetic variation in temperament and parasite resistance in beef cattle and their association with economically important traits. 4. Establish a DNA bank to utilize molecular markers to validate traits of economic importance.

APPROACH: Objective 2: Beefmaster-, Brangus-, Bonsmara-, and Romosinuana-sired heifers born in 2001 and 2002 from Angus and MARC III cows at the US Meat Animal Research Center were randomly assigned to two groups at weaning. One group was shipped to the Central Station in Baton Rouge, LA to establish a genetic (4 sire breeds) x environment (high plains, coastal prairie) interaction study for maternal and calf traits. Heifers at both locations will be exposed to MARC III bulls for the first calf and to Charolais bulls from MARC for the second and subsequent calves. Heifer age and weight at puberty, calving rate, and calf birth and weaning data will be collected. Feedlot and carcass data will be collected on steers from 5, 6, and 7 year old cows. Mixed model procedures will be used to evaluate the GxE interaction effects. Objective 3. Spring born calves (Angus-, Brahman-, Braford-, and Charolais-sired)will be evaluated for parasite resistance and/or temperament (chute behavior) from weaning to July 1 of the next year. All calves being evaluated for parasite resistance will be treated with fenbendazole at weaning. Fecal egg counts (FEC) will be made at weaning and every 45 days to July 1. Body weights, hair scores, and blood samples will be taken every 45 days to associate with FEC. Calves that show high FEC will be monitored closely to determine if they become stressed by high parasite loads. Calf behavior in a squeeze chute will be scored every 45 days throughout the evaluation period. Scores will range from 1 to 5 based on the scoring system of Dr. Temple Grandin. Where possible, chute exit speed will also be recorded. Both scoring systems (one subjective and the other objective) have been used successfully to measure temperament. Mixed model procedures will be used to determine breed differences and to estimate genetic (co)variances for parasite resistance and temperament and the association with postweaning growth and heifer conception as yearlings. Objective 4. Blood samples of cattle contributing to objectives 2 and 3 will be taken and DNA extracted for storage and future use. DNA extraction kits will be used to extract DNA which will be stored at -80 degrees C. Animal herd number and parental information will be recorded along with performance data.

PROGRESS: 2005/01 TO 2005/12
Beef cattle research in LA contributes to two objectives of S-1013. Cows at the Central Station in Baton Rouge contribute to Obj. 2 on tropically adapted breeds. Beefmaster (BM)-, Bonsmara (BO)-, Brangus (BR)-, and Romosinuano (RO)- sired F1 females were purchased from the USDA Meat Animal Research Center in NE to compare with similar F1 females maintained in NE. Brahman x Angus (BA) F1 females are used to compare to the MARC females in LA. Birth weights for Charolais-sired calves averaged 36.7, 38.1, 37.2, 37.2, and 36.3 kg from BA-, BM-, BO-, BR-, and RO-sired cows. 205d weaning weights averaged 242, 220, 216, 205, and 209 kg from BA-, BM-, BO-, BR-, and RO-sired cows. Palpation rates in October ranged from 83% for BR-sired cows to 100% for BA- and RO-sired cows. Calves weaned at the Hill Farm, Iberia, and Central Stations contribute to Obj. 3 on parasite resistance and/or temperament. Angus- (n=124) and Charolais- (n=184) sired calves were evaluated for chute score (CS) and exit velocity (EV) in July and at weaning at the Hill Farm. Chute scores, EV times, and 205-d weights were 2.05 vs 1.96, 2.08 vs 2.41 m/s (P treatment) of Angus and Brangus heifers born in 2005 were 229 and 247 kg, 256 and 251 d, 2.5 and 2.2, 3.2 and 3.7 m/s, and 246 and 193 eggs/g, respectively. Pregnancy rates were 90 and 72 % for 2004 Angus and Brangus heifers. Of Angus heifers born in 2003, 30 calved (29 kg average birth weight) and 27 weaned a calf (182 kg body weight at 230 d). Average cow weight and body condition score at weaning was 425 kg and 4.6. Eleven Angus and 12 Braford heifers born at the Central Station in 2004 were evaluated for temperament and FEC as outlined at the Iberia Station. Fecal egg counts were slightly higher in Angus (273 eggs/g) than Braford (118 eggs/g) at treatment after weaning, but remained lower and similar after treatment through July. Chute temperament and EV scores were similar for heifers in both breeds and were not related to pregnancy rate in Angus (64%) or Braford (58 %). Angus and Braford heifers gained similarly throughout the 288 days and weighed 379 and 388 kg in July. Angus (n=18), Brahman (n=12), and Braford (n=11) heifers born in 2005 are currently being evaluated for temperament and FEC observations.

IMPACT: 2005/01 TO 2005/12
Identification of cattle that are productive and docile can lead to more productive commercial herds in the southeast. Because of the hot and humid climate, control of internal parasites is necessary in most herds. Identification of cattle that are more tolerant to interal parasites than others may help to reduce the cost to control internal parasites through use of anthelmintics.

PUBLICATIONS: 2005/01 TO 2005/12
No publications reported this period

PROJECT CONTACT:

Name: Franke, D. E.
Phone: 225-578-3436
Fax: 225-578-3279
Email: dfranke@agctr.lsu.edu