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ANIMAL PRODUCTION |
* Department of Animal Sciences, Colorado State University, Fort Collins 80523-1171; and
and
Elanco Animal Health, Greenfield, IN 46140
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Abstract |
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 Top Abstract INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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Key Words: behavior • cattle • handling • ractopamine • temperament
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INTRODUCTION |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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), currently is approved for commercial use as a feed ingredient in swine and cattle finishing diets. Elanco Animal Health (Greenfield, IN) markets RAC as Paylean and Optaflexx, 2 separate product lines formulated specifically for swine and cattle, respectively.
Use of RAC (Paylean) in swine finishing diets has been shown to improve growth performance, dressing percent, and carcass leanness (Gu et al., 1991a,b; Crome et al., 1996). However, feeding swine RAC also may influence mobility, behavior, and susceptibility to stress during handling and transport (Schaefer et al., 1992; Marchant-Forde et al., 2003). Marchant-Forde et al. (2003) reported that, compared with a negative control group, swine fed a diet supplemented with 10 ppm RAC for 4 wk were more active, had higher heart rates and circulating catecholamine levels, and required more time and physical contact to be moved from their home pens to a scale for weighing. According to Geverink et al. (1998), pigs that are moved with difficulty are more likely to be handled roughly during transport.
Laudert et al. (2005a, b) reported that feeding RAC (Optaflexx) to cattle at a dosage of 200 mg·steer–1·d–1 for the final 28 to 32 d of the finishing period resulted in more rapid BW gains, improved G:F, heavier carcass weights, and higher dressing percentages. To date, however, no information has been reported concerning the effects of RAC supplementation on cattle behavioral traits.
The objective of this study was to examine the effects of feeding RAC at a dosage rate of 200 mg·steer–1·d–1 during the final 28 d of the finishing period on behavioral traits of steers differing in biological type during routine handling through a squeeze chute.
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MATERIALS AND METHODS |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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Four hundred twenty steers (6 to 9 mo of age), representing 3 biological cattle types (British, Continental crossbred, and Brahman crossbred), were obtained from 5 ranches. British-type steers included purebred Angus (n = 60, ranch A), British-composites (hybrids with a predominance of Red Angus, Angus, and Hereford influence, n = 40, ranch B), and Angus x Hereford crossbreds (n = 40, ranch C). Continental crossbreds were 50% Charolais x 50% British composite (n = 40, ranch B) or 50% Limousin x 50% Angus (n = 100, ranch D). The Brahman crossbred group consisted of 140 Beefmaster (37.5 to 50% Brahman x 50 to 62.5% British, ranch E) steers.
Steers were blocked by BW (7 blocks) within biological type (3 types) and assigned to 42 pens (6.1 m x 40 m per pen), each pen containing 10 animals. This resulted in each of the 21 biological type x block subclasses being represented by 2 paired pen-replicates, which were randomly designated as control [0 mg·steer–1·d–1 of Optaflexx (Elanco Animal Health, Green-field, IN)] or treatment (200 mg·steer–1·d–1 of Optaflexx).
An initial implant containing 20 mg of estradiol benzoate and 200 mg of progesterone (Component E-S with Tylan, VetLife, West Des Moines, IA) was administered to each steer at the beginning of the finishing period. Approximately 2 mo later, all steers were reimplanted (120 mg of trenbolone acetate and 24 mg of estradiol; Component T-ES with Tylan, VetLife). During finishing, cattle received a steam-flaked corn, alfalfa haybased diet (78.2% DM, 1.42 Mcal NEg/kg, 12.85% CP). Each pen was provided feed once daily; the daily ration was sufficient to allow ad libitum access to feed throughout a 24-h period.
Experimental treatments were initiated when paired pens were projected to be 28 d from harvest. Steers designated for treatment were administered RAC via a type-B medicated, ground corn supplement formulated to provide RAC at an average rate of 200 mg·steer–1·d–1. The supplement was mixed into the final ration at the time of daily feed delivery to the cattle. A similar, nonmedicated premix (identical formulation to that of the medicated supplement, except that RAC was excluded) was administered to control steers via the same procedure as used for those receiving RAC supplementation.
Scores for temperament/behavior were assigned to each steer 28 d after the initiation of treatment, as final individual BW were being obtained. A single, trained observer, who remained blinded with respect to the identity of control and treatment groups, recorded subjective scores for cattle behavior as individual animals entered a squeeze chute (entry scoring), while each animal was restrained in the squeeze chute (chute scoring), and as each animal was leaving the squeeze chute (exit scoring).
Entry Force and Speed Scoring
Animal handlers followed a standard protocol while loading cattle into the processing chute. If an animal refused to enter the squeeze chute under its own volition, the handler walked quickly from the animal’s head, past the shoulder, to a position behind the animal. This technique induces the animal to move forward because the handler walks past the animal’s point of balance (Grandin, 1994, 1996). While moving past the animal, from head to tail, the handler would vocally encourage the animal to step forward (using a "shh-shh" sound), without touching the animal.
The level of force required to move the animal into the chute was scored as follows. An entry force score of 1 was assigned to animals that entered the chute voluntarily or after encouragement without physical contact. If an animal refused to enter the chute with nonphysical encouragement, the handler would lightly tap the animal on the rump with her/his hand. Animals that entered the chute with this level of encouragement were assigned a score of 2. If a single impulse from an electric prod was required to move the animal forward into the chute, the animal was assigned an entry score of 3, and animals requiring more than 1 electrical impulse to move into the chute were assigned scores of 4. The speed at which each animal entered the squeeze chute also was scored (entry speed: 1 = walk, 2 = trot, 3 = run or gallop).
Chute Scoring
Scores reflecting the animal’s behavior while restrained in the hydraulic squeeze chute were assigned immediately after chute entry and once light pressure had been applied to the sides of the animal using the squeeze feature of the chute. Behavior in the chute was scored as follows: calm behavior = 1, restless shifting = 2, moderate struggling = 3.
Exit Scoring
Exit speed scores were used to characterize the speed at which animals left the chute when released. Animals that calmly walked out of the chute were assigned a score of 1, those that trotted from the chute were given a score of 2, and those that ran or galloped out of the chute were assigned a score of 3.
Statistical Methods
Subjective scores assigned to characterize animal behavior in the current study were not normally distributed, and the data were analyzed using nonparametric procedures. To examine the effects of RAC supplementation, matched pairs of pens were compared using Wilcoxon’s matched-pairs, rank-sum test (Sokal and Rohlf, 1973). The effects of biological cattle type were tested for significance using Kruskal-Wallis 1-way analysis of variance in SAS (SAS Inst. Inc., Cary, NC). Pen was used as the experimental unit for all analyses.
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RESULTS |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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. Supplementation with RAC did not affect entry force score, chute behavior score, or exit speed score. However, cattle supplemented with RAC entered the restraining chute with greater speed (P < 0.05) compared with steers that did not receive RAC during the final 28 d of finishing (Table 1). Percentages of cattle that walked, trotted, and ran into the chute were 59.6, 39.9, and 0.5%, respectively, for control steers vs. 46.6, 51.0, and 2.4%, respectively, for steers supplemented with RAC. The slightly greater speed at which the RAC supplemented steers entered the chute was not considered problematic.
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. Cattle types differed (P < 0.05) in entry force score and exit speed score. Continental crossbreds required greater (P < 0.05) force to enter the squeeze chute than did British or Brahman crossbred steers. In addition, Continental crossbred and Brahman crossbred steers left the processing chute with the greatest speed, whereas British steers moved most slowly out of the chute (Table 2). Biological cattle type did not affect scores for entry speed or behavior during restraint in the chute.
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DISCUSSION |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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), have been shown to influence growth rate (Burrow and Dillon, 1997; Voisinet et al., 1997b), frequency of the dark cutting condition (Voisinet et al., 1997a), incidence of carcass bruising (Fordyce et al., 1988b), and beef tenderness (Fordyce et al., 1988b; Voisinet et al., 1997a). Correspondingly, use of a growth enhancement product that elicits adverse behavioral changes, though it may have beneficial effects on growth performance, could be detrimental to beef carcass value and meat quality. Supplementation with RAC in the current study resulted in a 15% improvement in daily gain and an improvement in G:F of 18% (Gruber et al., 2005). In contrast to the findings of Marchant-Forde et al. (2003), who reported increased stress susceptibility and greater handling difficulty in swine supplemented with RAC, we observed no adverse effects on behavior of steers supplemented with RAC at a dosage rate of 200 mg·steer–1·d–1 during the final 28 d of the finishing period. To our knowledge, no previous studies have investigated behavior of cattle supplemented with RAC. However, Schroeder et al. (2005a, b) supplemented cattle with 0, 10, 20, or 30 ppm RAC and observed no detrimental effects of RAC supplementation on carcass or meat quality characteristics.
Previous studies comparing differences in temperament among cattle types suggest that Bos taurus cattle have calmer temperaments than do Bos indicus crossbreds (Hearnshaw and Morris, 1984; Fordyce et al., 1988a; Voisinet et al., 1997b). Differences in temperament observed among cattle types in our study suggest that British-type steers had the calmest temperaments, whereas Continental crossbreds and Brahman crossbreds tended to be more temperamental. Our results seem to be in general agreement with previous reports; however, because cattle representing the 3 biological types originated from different ranches, where they had been subjected to differing levels of human interaction prior to initiating the experiment, among-type differences in behavioral traits observed in the current study can be only partially attributed to cattle-type effects.
Cattle temperament has been assessed using a number of different methods, categorized by Burrow (1997) as restrained methods (those that assess behavior when the animal’s movement is physically restricted) or non-restrained methods (those that score behavior when the animal is free to move within a large test area). Burrow and Corbet (2000) evaluated restrained and nonrestrained temperament assessment methods and reported low correlations between "crush" (chute) scores (restrained assessment) and flight speed (time taken for an animal to cover a fixed distance after leaving the restraining device—nonrestrained assessment). Vann and Randel (2003) also reported a relatively low correlation between exit velocity (i.e., flight speed) and chute score but found that exit velocity was moderately correlated with pen score (another nonrestrained assessment of temperament). Burrow and Corbet (2000) suggested that flight speed and chute scores measure different aspects of animal behavior and concluded that, for animals with 50% or more Bos indicus inheritance, objective measurement of flight speed was the preferred method of assessing temperament. Baker et al. (2003) and Curley et al. (2003) also advocated use of an objective measure of exit velocity (i.e., flight speed) to assess differences in cattle temperament, as opposed to a subjective temperament score assessed while the animal was restrained in a chute.
In the current study, exit speed score (a subjective assessment of nonrestrained behavior similar to flight speed) seemed effective for identifying temperament differences among biological cattle types. Exit speed score (walk, trot, gallop), a practical, subjective assessment of temperament, that does not require specialized equipment for measurement, could be a useful, low-cost tool for cattle producers who wish to evaluate cattle temperament during routine handling of animals in commercial beef operations.
1 Corresponding author: J.Daryl.Tatum{at}Colostate.edu
Received for publication March 21, 2006. Accepted for publication July 16, 2006.
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LITERATURE CITED |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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