Zebu Cattle Adaptability

GENETIC A N D BIOLOGICAL ASPECTS OF ZEBU A D A P T A B I L I T Y 1 ,2 J. W. Turner Louisiana State University, Baton Rouge 70803

Summary

1. The direct measure of performance under measured environmental stress is the approach utilized by response scientists. The application is to control the environmental stresses reducing performance or to predict the ability of the animal to adjust to environmental stresses (Dowling, 1974; McDowell, 1974). 2. The classical genetic approach of fitness details a selective value for adapted animals to effect a population change i n harmony with existing environmental conditions (Falconer, 1960). Rohles (1974) presented an interesting concept for environmental research as the ecosystem complex. The ecosystem complex included: ( i ) physical factors defining the environment; (2) organismic factors, which are factors describing the animal, and (3) adaptive factors, those factors that interact with the Introduction physical factors and organism to allow for Adaptation is a broad term used to describe adaptation. While adaptation is a complex subthe ability of animals to adjust to environmen- ject, the application of knowledge concerning tal conditions or to infer genetic modifications Zebu cattle is important to beef production in that make animals more suitable for existence several environments. This paper will present under specific environmental conditions. Zebu, pertinent research that documents the adaptive Bos indicus, cattle are widely recognized as aspects of Zebu cattle and their utility as a adaptable to tropical and subtropical environ- genetic entity. ments that are restrictive to Bos taurus cattle. Bonsma (1973) presented a comprehensive However, objective measurements of traits and review of adaptation and beef cattle breeding. characteristics that directly affect adaption are Zebu, Bos indicus, cattle evolved in the Southlimited. Most work documents the effects of ern hemisphere and ~tdapted to muggy and environmental factors on production variables scorching environments. These include environor the broad effects of breed comparisons ments defined by mean monthly temperatures under specified environments. of 18 C or higher and relative humidity of 55% or higher. It was noted that humidity was of Discussion little importance compared to temperature. Research into adaptation can be viewed Therefore, particular emphasis was placed from two classical perspectives: on temperature effects in the discussion of Zebu cattle. Because Zebu cattle are smoothcoated, have primary hair follicles, have better =Presented at a symposium on "The Role of Zebu developed sweat and sebaceous glands than Bos Cattle in Efficient Beef Production" at the Annu. taurus cattle and can lose more moisture by Meet. of the Southern Sec. of the ASAS, Feb. 5, 1979, evaporation, they are cited as adaptable to hot in New Orleans, LA. ZPublished with approval of the Director of the climates. In addition, the ability to maintain Louisiana Agr. Exp. Sta. thermal equilibrium is a necessary factor for 1201 JOURNAL OF ANIMAL SCIENCE, Vol. 50, No. 6, 1980 The utility and documentation of traits and characteristics of Zebu, Bos indicus, cattle in beef production in the United States are discussed with reference to adaptation. Zebu cattle are uniquely suited to hot climates due to coat, hide, skin and hematological attributes. Form, growth and physiological aspects are unique genetic attributes which are different from those of Bos taurus cattle. Compared with Bos taurus cattle, Zebu cattle are lower in reproduction, later maturing, slower growing and lower in beef quality. Zebu cattle are valuable in crossbreeding, with adaptive aspects transmitted and large amounts of heterosis in growth, maternal effects and reproductive traits. (Key Words: Beef cattle, Adaptation, Zebu, Bos indicus, Production.)

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normal function and performance. Bonsma (1973) expanded Zebu attributes to include coat color, pigmentation, conformation, genetic adaptation to the source of nutrition (forages) and resistance to pests and disease. The implications are that Zebu cattle are adaptable to poorer quality forages and soils of low pH and are resistant to ectoparasites and diseases transmitted by ectoparasites. Frisch and Vercoe (1978) studied 15-month weights of Bos indicus, Bos taurus and crosses and listed Brahmans as resistant to ticks, worms, pinkeye, heat and nutritional fluctuations. Brahmans (Bos indicus) were also cited as having lower inherent voluntary feed intake and lower relative maintenance requirements. Howes (1963) reported that hematological comparisons of Brahman and Hereford cattle in Florida were related to respiration and adaptation. Brahman cattle were observed to have higher red blood cell counts, total cell volume and hemoglobin values. Venous blood of Brahman cattle had less carbon dioxide than did that of Herefords. These results imply that Brahman cattle are capable of maintaining lower respiration rates during periods of high ambient temperatures. Evans (1963) confirmed these hematological advantages for Zebu cattle as well as the effect of the advantages on adaptation to temperature stress. Allen (1962) compared Brahman and Jersey cattle skin temperatures and respiration rates at air tempetaures from 24 C to 35 C. Zebu cattle had lower respiration rates at all levels of skin temperature, and skin temperature of Zebus closely followed air temperature. Zebu cattle had the lower skin temperature below 24 C and the higher mean temperature above 35 C. It should be noted that Jersey cattle are generally accepted as adapted to warm climates. Cartwright (1955) documented advantages in heat tolerance of Brahman and F-1 crosses over Hereford cattle. Superior summer gains were cited as important measures of adaptive merit of Brahmans and the Brahman x Hereford crosses. Johnson (1963) cited the major factor favoring Brahman cattle as heat tolerance or the ability to respond to increasing heat loads. Tugwell et al. (1969) studied levels of Brahman breeding and color as factors affecting horn fly, Haematobia irritans (L.), attractiveness and(or) repellency. As Brahman breeding (percentage of blood) increased, actual fly counts decreased, regardless of color. Subse-

quent investigation of ambient temperature, humidity and sunlight in association with horn fly counts and respiration rate, surface temperature and moisture of the animal did not define attractiveness and(or) repellency. Brahman breeding was cited as the important variable. Brown et al. (1977) found lighter coat color to be important in reducing fly counts in Arkansas. Breed differences were important during periods of high fly populations. No specific reference to the Brahman breed was made, yet purebred cattle were studied. Rick (1962) established Bos indicus breeding as a factor promoting resistance to the cattle tick, Boopbilus microplus. Bos indicus x Bos taurus crosses were more resistant than were Bos taurus cattle. A portion of the resistance was termed innate. Strother et al. (1974) documented the resistance of Brahman cattle to the Lone Star tick, A m b l y o r n m a americanum. Both Brahman and Brahman • Hereford crosses were more resistant than Herefords. Steelman et al. (1973) and Steelman et al. (1976) documented the efficacy of Brahman characteristics in reducing weight loss due to mosquito attack. Brahman steers were found to be more tolerant to mosquito attack than were Herefords on the basis of weight gains. Dowling (1974) dismissed the notion that heat tolerance limits Bos taurus cattle in Australia. He cited the resistance of Bos indicus cattle to ticks and parasites and calving ease as the important adaptive attributes and suggested that crossbreeding with Bos taurus cattle is necessary to improve production efficiency. The environmental effects of nutritional status and breed x environment interaction on Zebu cattle are difficult to document. Zebu cattle are universally accepted as adapted to poor quality forages. Stated differently, they can survive and produce in restrictive environments. Most attribute this quality of Zebu cattle to a genetic ability to utilize forages more efficiently. Rogerson et al. (1968) compared Boran (Zebu) steers with grade Herefords (Bos taurus) on high energy diets and concluded that Zebu steers have lower dry matter intakes but do not use feedstuffs more efficiently. Zebu cattle had lower metabolic rates, and water intake was similar. Efficiency was measured as growth relative to feed intake. Lofgreen et al. (1975) reported that Brahman • British steers utilized energy more efficiently than British steers under a heat stress of warm drinking water (32.2 C) compared to cooled drinking water

ADAPTABILITY ASPECTS OF ZEBU CATTLE (18.3 C). Moore et al. (1975) reported a significant breed x diet (energy level) interaction in diet digestibilities. They observed that Brahman bull calves were more efficient on low energy (high roughage) diets than were Herefords, yet Herefords were superior to Brahmans on a high energy (low roughage) diet. The implication was that Brahman cattle utilize low energy diets more effectively than high energy diets. Related observations made by Bonsma (1973) verify that Zebu cattle founder readily under intensive feedlot conditions with moderate to high energy diets. Feed intake, nutritional requirements for growth and maintenance requirements for Zebu cattle may be different from those for Bos taurus cattle (Frisch and Vercoe, 1978). Evidence at least suggests advantages for Zebu cattle on roughage diets. Zebu cattle do not adapt to high energy feeding as readily as Bos taurus. The unique qualities of Zebu cattle in comparison to B o s taurus breeds are important considerations for the breeding decisions made by many cattlemen. Because Zebu cattle are humped and atypical in conformation, and appear by observation to be shallow and narrow in the heart girth and narrow in the crops, they may not be considered as acceptable beef animals. Zebu cattle grunt or bellow more than low, and their disposition is truly different. Zebu cattle are docile and quiet yet possess the ability to become aroused more quickly than do Bos taurus cattle. Zebu cattle are difficult to handle under forced or stress working conditions. Some will fight, jump or exhibit extremely nervous behavior. Others sulk and refuse to be moved when they tire or face unfamiliar surroundings. It is safe to say that more research into animal behavior is needed and that learning and understanding the Zebu psyche will be an interesting research area. Some Zebu cattle are extremely docile while others are totally unruly. Disposition is believed to be heritable, and it is the most important reason why Zebu cattle are not used more in crossbreeding. Zebu cattle are poorer in reproductive efficiency than Bos taurus cattle under subtropical conditions in the United States (Warnick, 1963; Reynolds, 1973; Wythe, 1970; Bazer, 1973). Howes (1963) stated that Brahman cows had lower ovulation rates than did Hereford cows. Also, lower levels of thyroid, adrenal and ovarian activity were cited as factors contributing to the Brahman's greater heat toler-

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ance but lower reproductive efficiency. Howes (1963) and Hentges and Howes (1963) indicated that Brahman cows milked more than Herefords and used feedstuffs and nutrients from body stores to lactate at the expense of reproduction. Delayed estrus and subsequent lower reproductive rates were obvious effects. Kincaid (1963) documented a lactation status x breed interaction in fertility (calving rate). Dry Brahman cows were 13% more fertile than wet Brahman cows, while wet Hereford cows bred better (10%) than dry Hereford cows. The Brahman breed of the United States has other unique reproductive qualities. Perinatal calving losses are normally greater in purebred Brahman herds (Reynolds, 1973). Franke et al. (1975) documented the incidence and characterized the weak calf syndrome in Brahman cattle. Purebred Brahman calves are often lacking in vigor at birth and are adversely affected by cool, moist conditions. Puberty occurs later in Zebu cattle than in Bos taurus breeds (Plasse et al., 1968b; Bazer, 1973). Late sexual maturity is a well-known characteristic of Zebu cattle. Brahman cattle have a gestation period of 292 days (Plasse et al., 1968c), and calving intervals average 410 days (Plasse et al., 1968a). Plasse et al. (1968b) observed a seasonal estrus activity in Brahman heifers, with spring and summer activity greatest. Zebu cattle are recognized as having excellent longevity and little dystocia (Wythe, 1970). Brahman cattle have been characterized as slow-growing feedlot cattle that are lower grading and produce less tender beef (Turner, 1973). Slower growth performance for purebred Brahman steers was also reported by Crockett (1973) and Peacock et al. (1973). Carpenter (1973) reported that compared to straightbred Brahman, British • Brahman crosses produced carcasses with increas~ed weight, grade, palatability and fat content with lower percentage lean and bone. Zebu purebreds are not recognized as efficient beef cattle but are desirable in restrictive environments. The genetic utility of Zebu cattle has been well documented in beef production systems. Zebu crossbreds, Bos indicus • Bos taurus, including reciprocal crosses, exhibit heterosis in several economically important traits. The greatest and most important hybrid effects are found in reproductive performance (Turner e t al., 1968; Bazer, 1973). Maternal heterosis is large for weaning weight (McDonald and Turner,

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1972). Preweaning and postweaning growth tra ts exhibit heterosis of e c o n o m i c significance and are well d o c u m e n t e d . Carptenter (1973) stated that heterosis for carcass traits was limited almost entirely to traits associated with carcass weight. The u l t i m a t e utility of Zebu cattle has been in well-defined crossbreeding programs. Achieving adaptation to hot climates and p o o r forage areas with Zebu crossbreeds via additive inheritance and utilizing h e t e r o t i c advantages in re!rroductive, maternal and g r o w t h - r e l a t e d traits is the m a n n e r in which breeders use Zebu cattle. As atypical cattle, t h e y excel in crossbreeding systems utilizing the additive inheritance of B o s t a u r u s breeds. Crossbreeds are intermediates that adapt in m u c h the same way as Zebu parental stock yet perform b e t t e r than the B o s t a u r u s parent breed. The success o f such crossbreeding has led to the estabTishment of several new breeds based u p o n percentage of blood and selection. The c o m m o n f a c t o r in most is that Zebu inheritance has been utilized for adaptation to produce in hot climates. It is i m p o r t a n t to n o t e that the South and S o u t h west are regions of relatively high temperatures in which a sizable portion o f the United States b e e f cattle p o p u l a t i o n is located. Zebu crossbred cattle can and do m o v e into m o r e t e m p e r ate zones, but the advantages of Zebu breeding apparently decline as B o s t a u r u s cattle b e c o m e b e t t e r adapted and p e r f o r m mo.re favorably. A d a p t a t i o n to cold w e a t h e r quickly b e c o m e s the more i m p o r t a n t consideration. Purebred Zebu cattle are found in greatest numbers in Texas, Florida and Louisiana. H o w ever, interest has allowed for expansion o f Zebu cattle into o t h e r states in the S o u t h and Southwest. Additionally, Zebu breeders have advanced interest in developing and recording different types of Zebu cattle. The A m e r i c a n Brahman Breeders Association currently maintains a single h e r d b o o k , while the Pan A m e r i c a n Zebu Association has separate h e r d b o o k s for Zebu Tejano, Indu-Brazil and Gyr cattle. Zebu cattle in the United States o c c u p y a unique position. Purebreds are normally n o t used in commercial p r o d u c t i o n , and m a n y c a t t l e m e n are u n i n f o r m e d a b o u t the m e r i t o f Zebu breeding. There is no questioning the effective use o f Zebu cattle for crossbreeding. Probably no o t h e r types or breeds have such a w e l l - d e f i n e d and accepted role in c o m m e r c i a l beef production.

Literature Cited

Allen, T . E . 1962. Responses of Zebu, Jersey and Zebu • Jersey crossbred heifers to rising temperatures, with particular reference to sweating. Australian J. Agr. Res. 13:165. Bazer, F. W. 1973. A twenty-year summary of heterotic effects on reproduction in Florida cattle. In M. Koger, T. J. Cunha and A. C. Warnick (Ed.) Crossbreeding Beef Cattle. Series 2. University of Florida Press, GainesviUe. Bonsma, J. C. 1973. Crossbreeding for adaptability. In M. Koger, T. J. Cunha and A. C. Warnick (Ed.) Crossbreeding Beef Cattle. Series 2. University of Florida Press, Gainesville. Brown, C. J., J. L. Lancaster and R. W. Parham. 1977. Treatment and breeding group effects on hornfly counts. J. Anim. Sci. 45 (Suppl. 1):41. Carpenter, Z. L. 1973. Effects of crossbreeding on carcass characteristics. In M. Koger, T. J. Cunha and A.C. Warnick (Ed.) Crossbreeding Beef Cattle. Series 2. University of Florida Press, Gainesville. Cartwright, T. C. 1955. Responses of beef cattle to high ambient temperatures. J. Anim. Sci. 14: 350. Crockett, J. R. 1973. Finishing calves from a crisscross breeding system. In M. Koger, T. J. Cunna and A. C. Warnick (Ed.) Crossbreeding Beef Cattle. Series 2. University of Florida Press, Gainesville. Evans, J. B. 1963. Adaptation to subtropical environments by Zebu and British breeds of cattle in relation to Erythrocyte characters. Australian J. Agr. Res. 14:559. Dowling, D. F. 1974. Discussion of the influence of environmental factors on cattle production. In Livestock Environment Affects Production, Reproduction, Health. ASAE, St. Joseph, MI. Falconer, D. W. 1960. Introduction to Quantitative Genetics. The Ronald Press Co., New York. Franke, D. E., J. D. Combs, Jr., W. C. Burns and W. W. Thatcher. 1975. Neonatal health status in Brahman calves and blood components. J. Anim. Sci. 40:193 (Abstr.). Frisch, J. E. and J. E. Vercoe. 1978. Utilizing breed differences in growth of cattle in the tropics. World Anita. Rev. (FAO) 25 ;8. ltentges, J. F., Jr. and J. R. Howes. 1963. Milk production. In T. J. Cunha, M. Koger and A. C. Warnick (Ed.) Crossbreeding Beef Cattle. University of Florida Press, Gainesville. Howes, J. R. 1963. Blood composition and physiology of Brahman and Herefords. In T. J. Cunha, M. Koger and A. C. Warnick (Ed.) Crossbreeding Beef Cattle. University of Florida Press, Gainesville. Johnson, J . E . 1963. Response to environment. In T. J. Cunha, M. Koger and A. C. Warnick (Ed.) Crossbreeding Beef Cattle. University of Florida Press, Gainesville. Kincaid, C. M. 1963. Crossbreeding in the southern region. In T . J . Cunha, M. Koger and A.C. Warniek (Ed.) Crossbreeding Beef Cattle. University of Florida Press, Gainesville. Lofgreen, G. P., R. L. Givens, S. R. Morrison and T. E. Bond. 1975. Effect of drinking water temperature on beef cattle performance. J. Anim. Sci. 40:223.

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McDonald, R. P. and J. W. Turner. 1972. Estimation of maternal heterosis in preweaning traits o f beef cattle. J. Anita. Sci. 35:1146. McDowell, R. E. 1974. Effect o f environment on the functional efficiency of ruminants. In Livestock Environment Affects Production, Reproduction, Health. ASAE, St. Joseph, MI. Moore, R. L., H. W. Essig and L. J. Smithson. 1975. Influence o f breeds o f beef cattle on ration utilization. J. Anim. Sci. 41:203. Peacock, F. M., G. W. Kirk, J. W. Carptenter, M. Koger and A. Z. Palmer. 1973. Feedlot performance of straightbred and crossbreds. In T. J. Cunha, M. Koger and A. C. Warnick (Ed.) Crossbreeding Beef Cattle. University of Florida Press, Gainesville. Plasse, D., M. Koger and A. C. Warnick. 1968a. Repro ductive behavior of Bos indicus females in a subtropical environment. III. Calving intervals, intervals from first exposure to conception and intervals from parturition to conception. J. A n i m . Sci. 27:105. Plasse, D., A. C. Warnick and M. Koger. 1968b. Repro ductive behavior o f Bos indicus females in a subtropical environment. I. Puberty and ovulation frequency in Brahman and Brahman • British heifers. J. A n i m . Sci. 27:94. Plasse, D., A. C. Warnick, R. E. Reese and M. Koger. 1968c. Reproductive behavior o f Bos indicus females in a subtropical environment. II. Gestation length in Brahman cattle. J. Anim. Sci. 27: 101. Reynolds, W . L . 1973. Reproduction o f Brahman, Angus, Africaoder, and their crosses at Jeanerette, Louisiana. In M. Koger, T. J. Cunha and A. C. Warnick (Ed.) Crossbreeding Beef Cattle. Series 2. University o f Florida Press, Gainesville. Rick, R. F. 1962. Studies on the resistance of animals to infestation with ticks. Australian J. Agr. Res. 13:532. Rogerson, A., H. P. Ledger and G. H. Freeman. 1968.

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Food intake and live weight gain comparisons o f Bos indicus and Bos taurus steers on a high plane

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