F.A. Thrift

REVIEW: Update on preconditioning beef calves prior to sale by cow-calf producers1

ABSTRACT Preconditioning is designed to reduce incidence of bovine respiratory disease by increasing the immunity of the calf in preparation for the stress of weaning and shipping as calves move from their birth location through the stocker and feedlot phases of the beef production cycle. Results summarized from various studies indicate buyers paid more for preconditioned relative to nonpreconditioned calves (premium values ranged from

Ramifications of Weaning Spring- and Fall-Born Calves Early or Late Relative to Weaning at Conventional Ages1

1.43 to

The Issue of Carcass Tenderness Expressed by Cattle Varying in Bos indicus Inheritance1

6.15/45.4 kg for studies that assessed statistical significance of values); however, premiums paid for preconditioned calves do not necessarily result in increased net profit for cow-calf producers (net profit values ranged from -

Review: Preweaning, Postweaning, and Carcass Trait Comparisons for Progeny Sired by Subtropically Adapted Beef Sire Breeds at Various US Locations123

89.92 to

Interaction Between Calf Sex and Calf Genetic Type for Preweaning Traits of Calves Varying in Percentage Brahman Breeding

53.71/calf). To realize the greatest monetary benefit from preconditioning, cow-calf producers should develop a reputation for integrity and market calves through special preconditioning sales.

Effects of Weaning Productivity, as Mediated Through Sire Selection, on Subsequent Pregnancy Rate of the Cow Herd1,2

Results summarized for spring- and fall-born calves indicate that, in general, if early weaned (EW) calves are fed some form of concentrate diet from time of EW until age at which they would be conventionally weaned (CW), their BW will be equal to or greater than the BW of calves allowed to nurse their dams and CW. Feedlot ADG and carcass weight tend to be less, carcass yield grade is equal, and the percentage of carcasses grading greater than or equal to Low Choice tend to be equal to or greater for EW cattle relative to CW cattle. When the stress of lactation is removed by EW, cows gain BW and condition and begin to cycle; pregnancy rate is increased. Subsequent preweaning productivity is similar for cows that were weaned early or late (LW) as calves relative to cows that were CW.

Longevity Attributes of Bos indicus × Bos taurus Crossbred Cows1

Abstract This review reveals that relative to Bos taurus cattle, cattle varying in Bos indicus inheritance, especially cattle that are > 1/2 Bos indicus inheritance, lack carcass tenderness. Because consumers are willing to pay for more tender beef, it seems imperative that the commercial beef cattle industry should refrain from producing cattle that are > 1/2 Bos indicus inheritance. Because of their Superior preweaning maternal performance, F 1 Bos indicus ♂ × Bos taurus 9 females and their resulting contemporary F 1 steer mates will continue to be produced by the commercial beef cattle industry in the Southeast and Golf Coast areas of the U.S. Further, as progeny testing for tenderness is expensive, it is suggested that the F 1 Bos indicus ♂ x Bos taurus 9 steers be identified by the commercial beef cattle industry so that the packing/ retail industries can utilize existing postmortem technology (electrical stimulation, blade tenderization, extended aging, calcium chloride injections) to partially alleviate the lack of tenderness expressed by carcasses resulting from these cattle.

Review: The Issue of Dystocia Expressed when Sires Varying in Percent Bos indicus Inheritance Are Mated to Bos taurus Females1

ABSTRACT This review, which represents a summarization of research results generated during an approximately 22-yr period, involves preweaning, postweaning, and carcass trait comparisons of progeny sired by Bos indicus (Brahman, Boran, Nellore, Indu-Brazil, Gir, Sahiwal), B. indicus-derivative (Brangus, Beefmaster, Santa Gertrudis, Gelbray, Simbrah), non-B. indicus (Tuli, Romosinuano, Bonsmara, Senepol) subtropically adapted, and traditional Bos taurus (Angus, Hereford, Charolais, Gelbvieh, Red Poll) sire breeds. Relative to Brahman-sired progeny, preweaning (weaning weight) and postweaning (postweaning ADG, feedlot ADG, final feedlot BW) performance is expected to be less for progeny sired by non-B. indicus subtropically adapted sire breeds. The non-B. indicus subtropically adapted sire breeds do contribute to less dystocia and appear to improve carcass merit, especially carcass tenderness, over the Brahman breed. Other B. indicus sire breeds, such as the Gir and Sahiwal, but not the Indu-Brazil, contribute to less dystocia compared with the Brahman breed. Relative to B. indicus and non-B. indicus subtropically adapted sire breeds, B. taurus sire breeds, especially Angus and Hereford, express superior carcass merit in regard to marbling score, QG, and tenderness.

Interaction between Calf Genetic Type and Subtropical Location for Preweaning Traits of Cattle Varying in Percentage Brahman Breeding

Two data sets were utilized to evaluate interaction between calf sex and calf genetic type for preweaning performance of calves varying in percentage (0, 50, 100) Brahman breeding. Data set I involved birth weight, preweaning average daily gain, and weaning weight records on 3562 Angus (AA), Brahman ♂ × Angus ♀ (BA) and Brahman (BB) calves; data set II consisted of birth weight, preweaning average daily gain and weaning weight records on 3752 Hereford (HH), Brahman ♂ × Hereford ♀ (BH) and Brahman (BB) calves. For both data sets, the calf sex × calf genetic type interaction was significant (P<0.01) except for preweaning average daily gain in data set II. In all cases, the significant interactions were represented by a change in magnitude rather than a change in rank for the two sexes of each calf genetic type. These results indicate that sex differences are expected to be much greater for Brahman-sired BA and BH calves than for calves of 0% (AA or HH) or 100% (BB) Brahman breeding. These increased sex differences are of greatest importance for birth weight because of the relationship that exists between birth weight and calving difficulty.

Expected Versus Realized Progeny Differences for Various Beef Cattle Traits1

The present study, conducted to determine the impact of level of weaning productivity on subsequent pregnancy rate of the cow herd, involved two locations in the Southern Region - University of Kentucky, Lexington and Hill Farm Research Station, Louisiana State University Agricultural Center, Homer. Differences in level of (WW) productivity were created by producing calves sired by high and average bulls selected on the basis of direct WW expected progeny differences (EPD) (Kentucky: low-accuracy yearling Limousin bulls, natural matings, 478 calvings, direct WW EPD between high and average bulls = 11.3 kg; Louisiana: high-accuracy Simmental bulls, AI matings, 120 calvings, direct WW EPD between high and average bulls = 9.2 kg). Realized differences for 205-d WW between high- and average-sired progeny were 13 kg (P<0.05) and 16 kg (P<0.01), respectively, for the Kentucky