Differentiation of the effects of somatotropin and enhanced growth rate on the occurrence of osteochondrosis in pigs

Abstract

of iomatotropin and enhanced growth rate on the occurrence of osteochondrosis in pigs. Can. J. Anim' One hundred ind twenty yorkshiie pigs, equal numbers of gilts and barrows, with an initial average weight of 69 kg were us.ec in the present experiment. The animili weri treated with 2 -mg d -r of recombinant porcine somatotropin-(rpST). either b{ dqY injecti6n or by siow-release implant, while the control animals were treated with a sham implant. The daily injection of rpST increased daily weight gain (P j O.OOOfi and decreased feed/gain ratio (P < 0.0001) and daily feed intake (P < 0.0001). Barrows grew faster fi, : O.OZ\ andate more feeO (f : 0.0001) than-gilts. On reaching -100 kg, all pigs were slaughtered' and 60 pigs itwo from each pen) were randomly selected for carcass evaluation. Carcass lean content was increased (P < 0 0001) and carcass fat content was decreased (P < 0.0001) in animals treated with rpST by daily injection. Animals treated with rpST by the slowrelease implant were not different from the control animals in terms of growth performance artd carcass characteristics. No overt lameness was observed in any of the pigs in the experiment. However, rpST treatment, regardless.of the method of administration, increased the incidence and severity ot-osteoctronoiosis and reduced glycbsaminoglycan concentration in the cartilage ofthe weightbearing area of humeral and femoial condyles. These changes were independent of enhanced growth rate and carcass lean content'The reiults indicated that somatotropin treatment predisposes pigs to osteochondrosis.

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

“…These results confirm our previous observation (He et al 1994) that increased mechanical stress due to enhanced growth rate was not the only factor influencing the occurrence of OC in pigs.…”

Analysis of different layers of joint cartilage from pigs treated with and without recombinant porcine somatotropin (rpST)

“…Cartilage lesion score was marginally increased (P < 0.07) in pigs injected daily with rpST (1.98) compared with pigs of rhe conrrol group (1.65). Similar effects on weight gain, feed/gain ratio and cartilage lesion score have previously been observed by us (He et al 1994 (Table 1) are consistent with those reported previously (He et al 1994 (Nakano et al 1979), has been reported to be an important molecule involved in endochondral ossification, a process of long bone growth (Hunter 1991).…”

“…collagen undgti.oiurninoglycan concentrations in the weight-Fresh humeral condyles from both elbows were collected beari-ng u.eu-of .loint "u.iitug" (He et al 1994 …”

“…J' Anim' It has been reported that the ad'minisiration of rpsr induces the expeiiment was-reviewed and approved by the.Univera high incidenci and severity of osteochondrosis in growing sity of Alberta Animal Care Committee to ensure adherence and-finishing pigs (Evock et al 1988), and results in reduced to Canadian Council of Animal Care guidelines. collagen undgti.oiurninoglycan concentrations in the weight-Fresh humeral condyles from both elbows were collected beari-ng u.eu-of .loint "u.iitug" (He et al 1994 (Brennan and-Aherne 1986) position of different layers of joint cartilage. The present and by light _microscopy (Nakano etal.…”