Effects of Ralgro Implants on Growth, Sexual Development, Carcass Characteristics, and Eating Quality of Bulls Implanted From Birth to Slaughter

Growth, performance, sexual development, carcass characteristics, and eating quality were evaluated on 40 fall-born Angus bulls. Twenty of the bulls were implanted five times with Ralgro at an average interval of 106 days, beginning near birth. The other 20 bulls served as nonimplanted controls. Bull calves remained with their dams on native southeast Kansas pasture for an average of 320 days; they were then allotted to drylot pens (feedlot beginning) and placed on a 75% concentrate ration. Bulls from each treatment were fed to target weights of 1000 and 1100 pounds, and then slaughtered. Ralgro implanting increased average daily gain 6.6% over that of the controls from birth to the feedlot beginning, and 9.4% from the feedlot beginning to the first slaughter endpoint (196 days on feed). Feed efficiency was improved 8.2%, with implanting when the first group of implanted and control bulls were slaughtered (196 and 231 days on feed, respectively). Implanting reduced semen quality, reduced the number of bulls producing semen, and depressed the development of reproductive organs. Sex drive was unaffected by implanting. Implanting resulted in fatter carcasses and tended to increase yield grades, but did not affect final quality grades. Lean from control carcasses tended to be firmer and have a finer texture, but color was not affected by implanting. Loineye steaks from implanted bulls were significantly more tender, as judged by taste panel ratings and by Warner-Bratzler shear forces.

Hull calves remained with their dams on native southeast Kansas pasture for an average of 320 days; they were then allotted to drylot pens (feedlot beginning ) and placed on a 75% concentrate ration.Bulls from each treatment were fed to target weights of 1000 and 1100 pounds, and then slaughtered.
Ralgro implanting increased average daily gain 6.6% over that of the controls from birth to the feedlot beginning, and 9.4% from the feedlot beginning to the first slaughter endpoint ( 196 days on feed ).Feed efficiency was improved 8.2%, with implanting when the first group of implanted and control bulls were slaughtered ( 196 and 231 days on feed, respectively } .
Implanting reduced semen quality, reduced the number of bulls producing semen, and depressed the development of reproductive organs.Sex drive was unaffected by implanting.
Implanting resulted in fatter carcasses and tended to increase yield grades, but did not affect final quality grades.Lean from control carcasses tended to be firmer and have a finer texture, but color was not affected by implanting.Loineye steaks from implanted bulls were significantly more tender, as judged by taste panel ratings and by Warner-Bratzler shear forces.

Introduction
Consumer demand for leaner beef and cattlemen's desire to increase efficiency have emphasized the need to study bulls as meat animals.
Previous research has shown that implanting bulls with Ralgro has improved their growth, performance, and carcass traits, but these advantages appear to depend on animal age and weight, and on implanting frequency.
1 Ralgro is a product of International Minerals & Chemical Corporation.
2Mention of products and companies is made with the understanding that no discrimination is intended and no endorsement implied.
Appreciation is expressed to the Strait Ranch, Florence, KS, for their cooperation and assistance in conducting this research.
A trial at K.S.U.(Cattlemen's Day, 1979) showed that implanting bulls every 100 days from birth to slaughter improved average daily gain, impaired sexual development, and reduced mounting activity.That trial also indicated that implanting may improve carcass traits and the eating quality of bull meat.
Our trial was conducted to evaluate the effects of implanting bulls with Ralgro on: 1) growth and performance; 2) sexual development; and 3) carcass and palatability (eating quality) characteristics.

Experimental Procedure
Twenty of 40 Angus bull calves were implanted with 36 mg of Ralgro within 3 days after birth, then were reimplanted at an average of 123, 198, 324, and 425 days of age.The remaining 20 bulls served as nonimplanted controls.
All bulls were born in September and October and remained with their dams on native southeast Kansas pasture for an average of 320 days.The bulls were then assigned to drylot pens (feedlot beginning) and placed on adjustment rations, before being finished on a 75% concentrate ration.bulls from each treatment were slaughtered at two target weights (1000 and 1100 pounds).
Each bull was weighed at the beginning of the finishing period and thereafter at regular intervals until slaughter; feed intake was moni tered.
Maximum circumference of the scrotum (scrotal circumference) of each bull was measured at an average of 331 days and again at 517 days of age.At an average of 374 days and again at 501 days, groups of four bulls were penned with three restrained heifers in heat.The number of n�unts, services, and other sexual activities were recorded on each bull for 10 minutes.Bulls were scored on a scale from 1 to 10 for libido (sex drive), with 1 being no interest and 10 being two services followed by mounts, mounting attempts, or further services.At an average age of 515 days, semen collection by electro-ejaculation was attempted on each bull.Collection continued until sperm were found in the ejaculate or until three attempts had been n2de.
At slaughter the testicles, penis, seminal vesicles, and pituitary gland were removed and weighed, and testicle volume and penis length were recorded.
Carcass quality grade, yield grade, lean color, lean firmness, and lean texture were evaluated after a 48-hour chill.
Loin steaks were removed from the shortloin of each carcass.The longissimus dorsi muscle (loineye) of one steak was evaluated by a trained taste panel for tenderness, juiciness, and flavor.Six 0.5-inch diameter cores were removed from another loineye steak and sheared with a Warner-Bratzler shear to mechanically measure tenderness.

Results and Discussion
Growth and performance; Average daily gain (ADG) and feed efficiency data are shown in Table 19.1.
From the feedlot beginning until the first group of bulls 1�as slaughtered (196 days), implanted bulls gained 9.4" faster (P<.01), with a 7 .9%advantage (P<.10) in feed efficiency, than did controls.
Feed efficiency for all implanted bulls up to the first slaughter (196 days) was 7.13 lbs of feed/lb of gain.Control bulls required 35 more days to reach the same target weight, and their feed efficiency was 7. 71 lbs of feed/lb of gain --an 8.2% advantage (P<.10} for implanted bulls.
Sexual developmeni;: Tdblt! 19.2 �llov1$ that testicular development w;is depressed (P<.05) by implanting.Sperm were successfully collected from all control bulls but from only 45i of the ioplar.tedbulls, and percent motility was lower (P<.05) for implanted bulls.Sex drive (libido) was not affected in this trial, which is in disagreement with an earlier trial at Kansas State (Cattlemen's Day, 1979) where bulls implanted with Ralgro had lower libido scores.
Because repeated implanting with Ralgro supresses sexual development in bulls, implanted bulls should not be used for breeding purposes.

Carcass and palatability characteristics:
Slaughter weight, average age at slaughter, hot carcass 11eight, and dressing percent are shovm in Table 19.3.
We cannot explain the inconsistency in dressing percentages for bulls within slaughter weight groups.
Table 19.4 shows that implanted bulls had more (P<.05)external fat (adjusted fat thickness} and more (P<.10)kidney, p elv ic, and heart fat than did the controls.
Yield grades tended (P <. 10) to be lower for control bulls, with no difference in loineye areas.Quality grades were similar between treatments, and no differences were found in lean color, but control bulls tended (P<.10) to have more desirable lean texture and firmness ratings.
Even though implanted bulls were slaughtered at an earlier chrono logical age, they tended (P<.10} to have higher carcass maturity scores.
A trained taste panel rated steaks from implanted bulls as being significantly more tender for myofibrillar tenderness, connective tissue amount, and overa 11 tenderness.
�larner-Bratz 1 er shear forces confi nned the taste panel tenderness ratings.Flavor intensity and juiciness ratings were similar between treatments.x A score of 10 = two services followed by munts, munting attempts, or further services; a score of l =no interest.

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Quality of Bulls Implanted From Birth to Slaughter J.R. Greathouse, M.C.Hunt, M.E.Dikeman, � L.R. Corah, C.L. Kastner, and R.J. Pruitt Summary Gr�wth, performance, sexual development, carcass characteristics, and eating qual ity were evaluated on 40 fall-born Angus bulls.Twenty of the bulls were implanted five times with Ralgro at an average interval of 106 days, beginning near birth.The other 20 bulls served as nonimplanted controls.
70.0 Semen collection by electro-ejaculation (avg.age -515 days) M eans in same row with different superscripts are different (P<.05).
c ,�eans in same row with different superscripts are different (P<.05).e,f Means in same row with different superscripts are different (P<.01).SA score of 4 r rR:>derately dark red color, slightly fine texture, or slightly soft firmness; 1 = very light cherry red color, very fine texture or very firm firmness.x A score of 8 = extremely intense flavor, extremely juicy, or extremely tender myofibrillar or overall tenderness; 1 =extremely bland, extremely dry, or extremely tough myofibrillar or overall tenderness.YA score of 8 = no connective tissue; 1 = abundant connective tissue.z Pounds of for c e required to shear through a 0.5-in.core of cooked steak.

Table 1�4 .
Effects of Ralgro-on bull carcass characteristics and palatability ratings a, �eans in same row with different superscripts are different (P<.10).