Responses of Beijing Black Hogs to Porcine Somatotropin

Abstract

Somatotropin treatment of U.S-breed finishing hogs improves feed efficiency, growth rate and carcass lean-to-fat ratio. Because Chinese-bred hogs have poorer feed efficiency, growth rate and lean-to-fat ratio than U.S. bred hogs, the characteristics affected by porcine somatotropin (PST) may respond differently to treatment. In the present experiment, Beijing Black finishing hogs (a composite of a local Chinese, Berkshire and Yorkshire breeds) were treated with PST for 28 d from average initial to final weights of 67.8 to 96.6 kg. In hogs individually fed as much as they would eat four times a day (n = 12/treatment group, six gilts and six barrows), feed efficiency was improved by 22.4 and 29.9% by 2 and 4 mg/d PST, respectively (P less than .01), primarily due to increased growth rate (22.1 and 32.6% greater than control, respectively, P less than .01); feed intake was not affected. Performance of group-housed and group-fed hogs (six/pen, four pens/treatment) administered 2 mg/d PST for 28 d (average initial and final weights of 66.5 +/- 1.7 and 94.0 +/- 2.4 kg, respectively) was similar (22.7% improved feed efficiency, P less than .01; 25% increased growth rate, P less than .01). At slaughter, last rib backfat thickness was decreased an average of 19.2% for hogs treated with 2 and 4 mg/d PST (P less than .01). Percentage of total muscle, obtained by physical separation of the half-carcass, was increased an average of 13.5% (P less than .01), whereas percentage of total fat was decreased 21.8% (P less than .01) in PST-treated hogs. The pH, water-holding capacity and meat color scores of longissimus muscle from PST-treated hogs did not differ from those of control hogs. Growth rate, feed efficiency and muscle weight responses to PST treatment were at least as large as those for U.S. breeds.

The effect of porcine somatotropin (pST) and gender on production parameters and tissue yield of pigs slaughtered at 135 kg live weight

“…Although sows (0.869 kg/day) and barrows (0.848 kg/day) had a slower rate of gain than boars (0.934 kg/day), pST had no significant effect on the rate of gain attained by any group of animals in this experiment. This is in contrast with results documented by earlier investigators who generally reported an increase in ADG (Campbell et al, 1989;McLaughlin et al, 1989). This response was, however, further noted to be dose dependent (Fabry et al, 1991;Klindt et al, 1995) with the former author noting some responses only at 6 mg per day.…”

The interrelationship between crude protein and exogenous porcine somatotropin on growth, feed and carcass measurements of pigs.

“…Results of these experiments confirmed previous observations that chronic daily injections of porcine somatotropin into growing pigs increased growth rate, lowered F/G, reduced backfat thickness (Campbell et al, 1988(Campbell et al, , 1989McLaughlin et al, 1989;Smith and Kason, 1990) and increased plasma concentrations of IGF-I (Walton and Etherton, 1989; Smith and Kasson, 1990). Also, our results showed that somatotropin-induced growth performance of pigs was related to concentrations of dietary CP.…”

Biochemistry and physiology of anabolic hormones used for improvement of meat production

“…The efficiency of pST effects depend on several factors such as sex, age, breed and environment. It has little effect in fast growing, lean animals (46), but the effect is more pro-6 nounced in Chinese breeds with a higher fat content (47). The metabolic effects are also enhanced in females and in castrated males if compared to intact males, which have a faster growth rate, a lower daily fat deposition and a higher endogenous production of anabolic sex hormones (48).…”