Porcine somatotropin and dietary lysine influence bone mineralization and mechanical properties of bones in finishing swine2

Abstract

The femur, a rib, and a third metacarpal were collected from 108 barrows (initial weight = 57 kg) and analyzed to determine the effects of porcine somatotropin (pST) and dietary lysine on bone mineralization and mechanical properties. In Exp. 1, pigs were injected daily with 4 mg of pST and fed diets containing 1.0% Ca and .9% P and either .6, .8, 1.0, 1.2, or 1.4% lysine. Control pigs (placebo injection) received the .6% lysine diet. Bone wall thickness (BWT) of the femur increased (linear, P < .05) but ash content decreased (linear, P < .10) as dietary lysine level increased. Stress and ash content of the rib also decreased (linear, P < .05) with increasing dietary lysine level. In Exp. 2, pigs were injected with either 4 or 8 mg/d of pST and fed diets containing 1.1% Ca and 1.0% P and either .8, 1.0, 1.2, or 1.4% lysine. Control pigs received the .8% lysine diet. Increasing pST dosage increased BWT of the femur (linear, P < .10) but decreased ash content (linear, P < .10). In the rib, increasing pST dosage reduced stress, modulus of elasticity (linear, P < .10), and ash content (linear, P < .01). Increasing lysine level resulted in increased BWT of the femur and decreased ash content of rib, femur, and metacarpal (linear, P < .10). These data indicate that pST administration in conjunction with increasing lysine levels decreases bone ash content but increases BWT of finishing pigs.

Effects of recombinant porcine somatotropin (rpST) on joint cartilage and axial bones in growing and finishing pigs

“…*Signihcant at P < 0.05 level of probability. (Goodband et al 1993). Our experiment demonstrated similar effects of rpST on the ash content ofvertebrae and ribs (Table 5).…”

“…Our experiment demonstrated similar effects of rpST on the ash content ofvertebrae and ribs (Table 5). The reason that the loss of bone ash observed in the present experiment was greater than reported in previous studies (Goodband et al 1993) is unknown. Goodband et al (1993) suggested that an increased cellular requirement for calcium and phosphorus combined with the lower feed intake usualy observed with rpST-treated pigs may explain the lower mineralization of bones of rpST-treated pigs.…”

“…The reason that the loss of bone ash observed in the present experiment was greater than reported in previous studies (Goodband et al 1993) is unknown. Goodband et al (1993) suggested that an increased cellular requirement for calcium and phosphorus combined with the lower feed intake usualy observed with rpST-treated pigs may explain the lower mineralization of bones of rpST-treated pigs. Carter et al (1991) reported that rpST-treated pigs required higher dietary Ca and P levels to maximize bone strength and mineralization.…”

“…1977;Lundeheim 1987). It is not known whether the high incidence and severity of OC in rpST-treated Studies on the effect of rpST on the physical properties ofpig bones indicate that bone strength is decreased (Goodband et al 1993) possibly due to an increased water content in the bones of pigs treated with rpST (Caperna et al 1989). …”

“…Ash content in limb bones was reduced (Goodband et al 1993), but this reduction was not significant, possibly because limb bones are not as sensitive to demineralization as axial bones, such as vertebrae or ribs.…”