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Comparison of the effects of recombinant ovine, bovine and porcine growth hormones on growth, efficiency and carcass characteristics in lambs
Livestock Production Science, 37 ( 1994 ) 311-321 Elsevier Science B.V., Amsterdam
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Comparison of the effects of recombinant ovine, bovine and porcine growth hormones on growth, efficiency and carcass characteristics in lambs G . S . G . S p e n c e r , A. S c h u r m a n n , C. B e r r y , J.E. Wolff, J.R. N a p i e r , S.C. H o d g k i n s o n a n d J.J. Bass Growth Physiology, Ruakura Agricultural Centre, Hamilton, New Zealand (Accepted 28 May 1993 )
ABSTRACT The effects of daily administration of recombinantly derived ovine growth hormone (oGH) on live weight gain, food conversion and carcass composition were studied in young lambs and the effects compared with those obtained by administration of porcine (p) or bovine (b) growth hormone (GH). Forty-eight female Coopworth lambs were reared on a complete pelleted diet and, at 16 weeks of age, were allocated to one of four treatment groups. Each lamb received a daily s.c. injection of either oGH, bGH, pGH (0.1 mg/kg bodyweight) or vehicle. Food intake was measured daily and liveweights were measured weekly for 4 weeks after which the lambs were slaughtered for measurement of carcass characteristics and organ weights. Both the oGH- and bGH-treated lambs grew faster than controls (P<0.01) and had heavier carcasses at slaughter. No significant difference from control animals could be found for any treatment group with respect to food intake or relative appetite, but the oGH- and bGH-treated lambs had a better food conversion efficiency (P< 0.001 ). With the exception of reduced carcass fatness (P< 0.01 ) for bGH-treated lambs, no major effect of GH treatment could be detected on wool growth or carcass characteristics. Both oGH and bGH treatment resulted in increased plasma concentrations of IGF-1 (P<0.01) compared with controls and pGH-treated lambs. All GH-treated Iambs produced antibodies against the GH with which they were injected. Key words: Lambs; Growth hormone; Performance; IGF-1
INTRODUCTION Experiments on the administration of exogenous growth hormone (GH) h a v e p r o d u c e d i n c o n s i s t e n t e f f e c t s o n w e i g h t g a i n i n l a m b s ( S p e n c e r , 1 9 8 7 ). Administration of pituitary-derived ovine (o) GH to lambs has sometimes r e s u l t e d i n i n c r e a s e d w e i g h t g a i n ( W a g n e r a n d V e e n h u i z e n , 1978 ), w h i l e o n o t h e r o c c a s i o n s n o s t i m u l a t i o n o f g r o w t h h a s b e e n o b s e r v e d ( W h e a t l e y et al.,
Correspondence to: G.S.G. Spencer, Growth Physiology, Ruakura Agricultural Centre, Private Bag, Hamilton, New Zealand,
0301-6226/94/$07.00 © 1994 Elsevier Science B.V. All rights reserved. SSDI 0 3 0 1 - 6 2 2 6 ( 9 3 ) E 0 0 5 8 - Z
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1966; Muir et al., 1983 ). Possibly this inconsistency is a result of differences in experimental conditions, such as nutrition (MacRae et al., 1991 ), and it has been suggested that the protein anabolic response may be a better measure of GH efficacy. Reports on the effects of various GH preparations on indicators of the integrated protein anabolic response, such as carcass composition, and on food conversion efficiency (FCE) have been more consistent (Spencer, 1987; McBride and Moseley, 1991 ). The amino acid sequence of ovine and bovine (b) GH are similar (Warwick et al., 1989 ) and administration of bGH, of both pituitary (Wolfrom et al., 1985; Butler-Hogg and Johnsson, 1987; Rosemberg et al., 1989) and recombinantly derived sources (Johnsson et al., 1987; Sinnett-Smith et al., 1989; Zainur et al., 1989), has resulted in effects on growth and carcass composition similar to those found using pituitary-derived oGH. At the time this study commenced, there were no reports on the efficacy of recombinantly-produced porcine (19) GH or oGH on performance characteristics in lambs. After the start of this study, McLaughlin et al. ( 1991 ) reported a trial with recombinant pGH in lambs, but to date there have been no reports of the use of recombinant oGH in any species. The recent availability of adequate quantities of recombinant oGH, together with recombinant bGH and pGH, has allowed the present study on the comparative effectiveness of these three growth hormones on growth, food intake, food conversion efficiency and carcass characteristics of growing lambs. MATERIALSAND METHODS
Growth hormone preparations Recombinant bGH (Lot 7368C-91 X) was a gift from American Cyanamid Co. (Princeton, New Jersey, USA). Recombinant pGH and oGH were provided by Bunge (Australia) Pty.Ltd. (Melbourne, Australia). Following repurification, all three growth hormones consisted primarily of a monomeric GH peak on fast protein liquid chromatography (FPLC) with little evidence ofdimers. All GH preparations were tested in a bioassay to assess their ability to stimulate growth. Each day, for 6 days, 2 mg/kg bodyweight of the preparations were injected subcutaneously in a strain of GH-deficient rats (Charlton et al., 1988 ). All three preparations stimulated a significant increase in liveweight gain with no differences amongst the preparations (Fig. 1 ). Animals Forty-eight female Coopworth crossbred lambs were used. The lambs were weaned from the ewes at 8 weeks of age and then fed on a lucerne-barley pelleted diet (60% lucerne, 30% barley, 5% linseed oil, 5% molasses; providing 17.5% crude protein and 10 MJ/kg DM metabolisable energy). The lambs
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Fig. 1. Body weight of growth hormone-deficient dwarf rats both before and after treatment with: saline, or 2 m g / k g per day of oGH, b G H or p G H by subcutaneous injection. Values are means _+SEM with n = 6 in each group. ** controls differ significantly ( P < 0.01 ) from all other groups.
were housed in individual adjacent pens with ad lib. access to food and water throughout the trial. All lambs were completely acclimatized to the diet and the housing conditions by the start of the experiment. At 16 weeks of age ( _ 3 days) the lambs were weighed prior to the start of treatment and allocated to one of four groups. The mean pre-treatment weight was 22.8_+0.22 kg and lambs were allocated to treatment groups such that both mean growth velocity in the preceding week, and initial mean weights were similar. Treatment consisted of daily subcutaneous injections of either: 0.1 m g / k g per day o f b G H , p G H or oGH, or a similar volume (0.5 ml) of alkaline saline vehicle. The animals were weighed weekly and the doses adjusted each week on the basis of the mean weight of the group. A new batch of each GH solution was prepared each day. A weighed amount of food (in substantial excess of predicted requirement) was offered to each lamb daily and refusals for each lamb were measured daily. After 4 weeks of treatment food was withheld from the lambs overnight prior to slaughter. The liver, kidney and thymus were removed at evisceration and weighed. Hot carcasses were weighed and dressing percentage calculated. Carcass lengths (from the base of the gambrel to the anterior of the brisket) were measured and the carcasses were then chilled overnight and quartered at the tenth rib. Rib-eye measurements (width, length and area) were made and half the carcass was frozen, minced and analysed for chemical composition (Kirton et al., 1962). Mid-side 10 cm 2 wool-patch clips were taken both before and after treatment as an measure of wool growth.
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Endocrine and immune responses Blood was collected by jugular venepuncture each week and the plasma separated for storage at - 20°C. Plasma insulin-like growth factor-1 (IGF-I) concentrations were measured by radioimmunoassay (Hodgkinson et al., 1991 ) following dissociation from binding proteins using acid-ethanol cryoprecipitation. Radiolabelled preparations of the bGH, oGH and pGH were made using the Iodogen method (Salacinski et al., 1981 ) as previously described (Spencer et al., 1991 ). These tracers were used to detect the presence in the plasma of antibodies to the growth hormones. The antibodies were assessed by incubating the sera at various dilutions to determine the dilution that bound 50% of added label. These dilutions (between 1:5 and 1: 10) were then used in a radioimmunoassay (Spencer et al., 1991 ), but using a 6% polyethylene glycol separation system and a standard curve of 0 - 64000 ng/ml of the appropriate GH preparation. Antibody binding capacity and affinity were estimated using Scatchard analysis on plasma samples obtained during the fourth week of the experiment. Statistical analyses All data (except antibody results) were analysed by ANOVA with co-variate adjustment for initial body weight or carcass weight for pre- and postmortem measurements, respectively. RESULTS
Growth and carcass characteristics The growth responses to the various treatments are summarized in Table 1. There was no significant difference in growth rate between bGH and oGH. Both treatments, however, resulted in significantly faster growth than that observed in control lambs (38% and 26% greater, respectively). There was no difference between the growth rates of pGH-treated and control lambs. The increased liveweight was reflected in heavier carcass weights in the oGH- and bGH-treated animals, significantly so ( P < 0.05 ) in the latter group, but there were no differences among the treatment groups with respect to measurements of carcass length or rib-eye dimensions, when adjusted for carcass weight (Table 2 ). Liver weight was significantly greater ( P < 0.01 ) in the bGH-treated animals, while kidney weight was lower ( P < 0.05 ) in the pGHtreated lambs. Chemical composition analyses revealed that the bGH-treated animals had a lower proportion of body fat ( P < 0.01 ) and increased water ( P < 0.05 ) compared with controls, but no differences were found in carcass composition among the controls, oGH or pGH groups. There was no significant effect of oGH, bGH or pGH on wool growth.
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TABLE 1 Weekly live weight, average daily food intake ~, relative appetite (intake/weight) and overall food conversion efficiency (FCE: Weight gain/food intake) in lambs treated for 4 weeks with either vehicle, oGH, b G H or pGH 2 Trait
Weight (kg) Week 0 Week 1 Week 2 Week 3 Week 4 Food intake, g / d Appetite, g intake/g weight FCE
Treatment Control
oGH
bGH
pGH
sed
23.0 24.2 26.6 28.2 29.5 1341 51 0.17
22.9 25.0 a 27.8 b 29.5 c 31.2 c 1448 53 0.21 c
22.9 25.0 a 27.9 b 30.2 c 32.1 c 1373 50 0.24 c
22.2 24.4 26.7 28.1 29.5 1305 50 0.18
0.65 0.31 0.43 0.43 0.46 79 2.7 0.01
ap< 0.05, bp< 0.01, cp< 0.001 compared with control values. ~Food intake is air-dried weight (approximately 88% DM). 2Food intake, appetite and FCE are adjusted for initial live weight.
TABLE 2 Carcass dissection and chemical composition analyses of Iambs treated over 4 weeks with either vehicle, oGH, b G H or pGH Trait
Live weight, kg Hot carcass weight, kg Dressing, % Liver, g Kidney, g Kidney fat, g Thymus, g Ribeye area, cm 2 Carcass length, m m Femur length, m m Tibia length, ram Carcass fat, % Carcass water, % Carcass ash, % Carcass protein, % Wool weight, g/10 cm 2 skin
Treatment
pooled sed
Control
oGH
bGH
pGH
27.6 13.0 47.1 529 94 184 49 10.57 874 247 174 23.0 56.1 4.0 17.0 5.68
28.3 13.5 47.7 556 90 210 56 11.16 876 240 171 23.3 56.0 3.7 17.1 5.19
29.5 b 13.8 a 46.8 581 b 95 197 53 11.21 897 245 174 20.1 b 58.0 a 4.2 17.8 5.89
27.0 12.8 47.4 489 85 a 189 43 10.57 879 248 175 22.6 56.2 4.0 17.2 5.17
ap< 0.05, bp< 0.01 compared with control values.
0.74 0.39 0.67 24.4 3.5 18.5 5.1 0.51 12 5.1 3.5 0.9 0.7 0.2 0.3 0.12
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TABLE 3
Plasma concentrations o f IGF-1 ( n m o l / L ) during daily treatment with either vehicle, o G H , b G H or pGH I
Treatment
Week Week Week Week
1 2 3 4
Control
oGH
bGH
pGH
24.1 _+ 1.9 23.1 _+ 1.9 16.5_+0.5 14.0-+ 0.8
30.8_+ t.0 a 27.1 + 1.5 20.1 + 0 . 9 a 17.9_+ 1.9 a
29.2_+ 1.9 36.3-+ 1.3 b 22.8-+ 1.0 b 20.1 _+ 1.3 a
23.7_+0.6 24.0_+3.0 16.7_+0.6 13.4_+0.5
ap < 0.01, cp < 0.001 compared with control values. ~Values are means -+ SEM. TABLE4
Mean ( _+S E M ) antibody capacity and affinity in lambs following 4 weeks of daily treatment with o G H , b G H or p G H Item
Binding capacity, mol/1 Binding affinity, 1/mol
Treatment oGH
bGH
pGH
1.01 _+0.18X 10 -7 5.10_+0.76)< 106
1.61 + 0 . 5 7 × 10 - t ° 2.17_+0.48)< 10 ~°
2 . 4 8 + 0 . 6 7 × 10 -~° 1.21 _+0.49× 10 ~°
Food intake and conversion There were no differences among the treatment groups with respect to average daily food intake (ADFI) and relative appetite (ADFI/kg liveweight). However, food conversion efficiency (FCE; weight gain/kg food intake) was enhanced in the oGH and bGH groups compared with the controls (Table
1). Endocrine and immune responses Growth hormone treatment was associated with increased plasma IGF-1 concentrations in the oGH and bGH groups compared with the control and pGH groups (Table 3). Significant binding of radiolabelled oGH, bGH or pGH was observed only in the plasma of GH-treated lambs (Table 4 ). DISCUSSION
The use of recombinantly-derived oGH has not been previously reported, and the results of this experiment indicate that recombinant oGH is able to stimulate an increase in plasma IGF-1, growth rate and FCE when given to lambs.
EFFECTS OF GROWTH HORMONES
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The growth-stimulating effect of recombinant bGH administration on growth rate of lambs concurs with results reported by most (Pullar et al., 1986; Zainur et al., 1989; McLaughlin et al., 1991 ) but not all workers (Johnsson et al., 1987; Sinnett-Smith et al., 1989; Sun et al., 1992 ). It has been suggested that the plane of nutrition (particularly with regard to protein) may be an important factor in the response of pigs to GH (Etherton, 1989 ). In the present study the lambs were fed ad lib. with a relatively high protein diet and this may have influenced the positive effect of bGH. However, the relationship between orally ingested protein and amino acid absorption in ruminants is far from clear (Clarke et al., 1966). The effect ofbGH in improving FCE and decreasing carcass fatness in sheep has been consistent, and the results of the present study are similar to those previously reported. The lack of effect of bGH on wool growth is in agreement with a recently published report (Sun et al., 1992 ) in which a similar dose of recombinant bGH was used. There is, however, no general consensus on the effects of exogenous GH treatment on wool growth. Some workers have reported increased wool growth (e.g., Johnsson et al., 1987) while others reported decreased wool growth with GH administration (e.g., Wynn et al., 1988 ). It has also been reported that wool growth increases following cessation of GH treatment (Wynn et al, 1988 ), though such measurements could not be made in the present study. The lack of effect of recombinant pGH on growth rate of lambs is in agreement with the contemporary study by McLaughlin et al. ( 1991 ). This is not due to an inherent biological inactivity in this pGH preparation, since it was able to stimulate growth in a GH-deficient strain of dwarf rats. The lack of effect of pGH on growth rate in lambs is mirrored by its lack of effect on plasma IGF- 1 concentrations and, indeed, no effect on any aspect of carcass composition or food utilization. These results indicate that the pGH, although showing 91% sequence homology with oGH was not able to bind sufficiently to the oGH receptor to elicit a measurable response. McLaughlin et al. ( 1991 ) reported antibody titres to pGH at an early stage of treatment, and argued that it was the appearance of these antibodies that reversed the apparent, yet transient, effect of pGH on lamb growth noted in their study. However, in the present study, pGH had no effect on growth even in the first week of treatment, indicating that the inability of pGH to stimulate growth in Iambs is more likely to be due to a lack of binding to the oGH receptor, rather than as a consequence of antibody production; a contention supported by the positive effects of both oGH and bGH, although they also produced antibodies. All lambs produced antibodies against the GH preparations, but in all cases the affinities were low when compared with the affinity of either the high affinity ( 1013 L / m o l ) or the low affinity ( 1012 L/mol) GH receptor in sheep (Breier et al., 1987 ). Plasma from lambs given oGH showed a very low affin-
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ity, but relatively high capacity, binding of tracer compared with the pGHand bGH-treated lambs. It seems unlikely that this reflects a higher production of antibody to the oGH than to the other GH preparations, but may indicate the presence of a circulating oGH binding protein (Davis et al., 1992). There has generally been much inconsistency among studies in response to GH administration, particularly in ruminant species. Some of the problems (e.g. nutrition) associated with this variability have been discussed, but the use of heterologous preparations has also been suggested as a reason for this unpredictability (Chung et al., 1985 ). The similarity of the growth and plasma IGF-1 responses following bGH and oGH administration to lambs confirms the indication obtained from studies using pituitary-derived ovine and bovine growth hormones that bGH is equipotent to oGH in lambs. There appears to be an association between plasma IGF-1 response to GH administration and the growth rates in the different groups. The greater liver weight in the oGH- and bGH-treated lambs may have had a role in the increased IGF- 1 concentrations in these lambs, but whether the increased IGF1 caused, or resulted from these changes is not clear. In conclusion, this study reports, for the first time, the use of recombinantly-derived oGH to increase growth rate and FCE in lambs. It also confirms that daily injection of bGH can stimulate growth, carcass leanness and FCE in lambs and indicates that recombinant oGH and bGH are equipotent in lambs. By contrast, pGH had no effect on any aspect of performance studied. ACKNOWLEDGEMENTS
We are grateful to H. Burrill of Bunge (Australia) Pty. Ltd. for the gift of recombinant oGH and pGH and to Dr A.J. Mudd of American Cyanamid for the bGH. We also thank Dr Neil Cox for statistical analysis of the data.
REFERENCES Breier, B.H., Gluckman, P.D. and Bass J.J., 1987. The somatotrophic axis in young steers: influence of nutritional status and oestradiol- 17fl on hepatic high- and low-affinity somatotrophic binding sites. J. Endocrinol., 116:169-177. Butler-Hogg, B.W. and Johnsson, I.D., 1987. Bovine growth hormone in lambs: effects on carcass composition and tissue distribution in crossbred females. Anim. Prod., 44:117-124. Charlton, H.M., Clark, R.G., Robinson, I.C.A.F., Porter Goff, A.E., Cox, B.S., Bugnon, C. and
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Bloch, B.A., 1988. Growth hormone deficient dwarfism in the rat: a new mutation. J. Endocrinol., 119: 51-58. Chung, C.S., Etherton, T.D. and Wiggins, J.P., 1985. Stimulation of swine growth by porcine growth hormone. J. Anim. Sci., 60:118-130. Clarke, E.M.W., Ellinger, G.M. and Phillipson, A.T., 1966. The influence of diet on the nitrogenous components passing to the duodenum and through the lower ileum of sheep. Proc. Roy. Soc.(B), 166: 63-79. Davis, S.L., Graf, M., Morrison, C.A., Hall, T.R. and Swift, P.J., 1992. Identification and partial purification of serum growth hormone binding protein in domestic animal species. J. Anim. Sci., 70: 773-780. Etherton, T.D., 1989. The mechanisms by which porcine growth hormone improves pig growth performance. In: R.B. Heap, C.G. Prosser and G.E. Lamming (Editors), Biotechnology in Growth Regulation. Butterworths. London. pp 97-105. Hodgkinson, S.C, Bass, J.J. and Gluckman, P.D., 1991. Insulin-like growth factor binding proteins in sheep: effect of recombinant growth hormone and nutritional status. Domest. Anim. Endocrinol., 8:345-351. Johnsson, I.D., Hathorn, D.J. Wilde, R.M., Treacher, T.T. and Butler-Hogg, B.W., 1987. The effects of dose and method of administration of biosynthetic somatotropin on live-weight gain, carcass composition and wool growth in young lambs. Anim. Prod., 44: 405-414. Kirton, A.H., Barton, B.A. and Rae, A.C., 1962. The efficiency of determining chemical composition of lamb carcasses. J. Agric. Sci., 58:381-386. MacRae, J.C., Bruce, L.A., Hovell, F.D.DeB., Hart, I.C., Inkster, J., Walker, A. and Atkinson, T., 1991. Influence of protein nutrition on the response of growing lambs to exogenous bovine growth hormone. J. Endocrinol., 130:53-61. McBride, B.W. and Moseley, W.M., 1991. Influence of exogenous somatotropin on the components of growth in ruminants. In: P. van der Wal, G.M. Weber and F.J. van der Wilt (Editors), Biotechnology for control of growth and product quality in meat production: implications and acceptability. Pudoc. Wageningen. pp 91-103. McLaughlin, C.L., Rogan, G.J., Buonomo, F.C., Cole, W.J., Hartnell, G.F., Hudson, S., Kasser, T.R., Miller, M.A. and Baile, C.A., 1991. Finishing lamb performance responses to bovine and porcine somatotropins administered by Alzet minipumps. J. Anim. Sci., 69: 4039-4048. Muir, L.A., Wien, S., Duquette, P.F., Rickes, E.L. and Cordes, E.H., 1983. The effects of exogenous growth hormone and diethylstibestrol on growth and carcass composition of growing lambs. J. Anim. Sci., 56: 1315-1323. Pullar, R.A., Johnsson, I.D.and Chadwick, A.M.C., 1986. Recombinant bovine somatotropin is growth-promoting and lipolytic in fattening lambs. Anim Prod., 42:433-434 (Abstr). Rosemberg, E., Thonney, M.L. and Butler, W.R., 1989. The effects of bovine growth hormone and thyroxine on growth rate and carcass measurements in lambs. J. Anim. Sci., 67: 33003312. Salacinski, P.R.P., McLean, C., Sykes, J.E.C., Clement-Jones, V.V. and Lowry, P.J., 1981. lodination of proteins, glycoproteins and peptides using a solid-phase oxidising agent 1,3,4,6tetrachloro-3a,6ct diphenyl glycoluril (Iodogen) Anal. Biochem., 117:136-146. Sinnett-Smith, P.A., Woolliams, J.A., Warriss, P.D. and Enser, M., 1989. Effects of recombinant DNA-derived bovine somatotropin on growth, carcass characteristics and meat quality in lambs from three breeds. Anim. Prod., 49:281-289. Spencer, G.S.G., 1987. Biotechnology in the potential practical application of somatotrophic hormones for improving animal performance. Reprod. Nutr. Develop., 27B: 581-589. Spencer, G.S.G., Bass, J.J. Hodgkinson, S.C., Edgley, W.H.R and Moore, L.G., 1991. Effect of intracerebroventricular injection of IGF-1 on circulating growth hormone concentrations in the sheep. Domest. Anim. Endocrinol., 8:155-160. Sun, Y.X., Michel, A., Wickham, G.A., McCutcheon, S.N., 1992. Wool follicle development,
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wool growth and body growth in lambs treated from birth with recombinantly derived bovine somatotrophin. Anim. Prod., 55: 73-78. Wagner, J.F. and Veenhuizen, E.L., 1978. Growth performance, carcass deposition and plasma hormone levels in wether lambs when treated with growth hormone and thyroprotein. J. Anim. Sci., 47 (Suppl 1 ): 397 (Abstr). Warwick, J.M., Wallis, O.C. and Wallis, M., 1989. Cloning, sequence and expression in Escherichia coli of cDNA for ovine pregrowth hormone. Biochim. Biophys. Acta, 1008: 247-250. Wheatley, I.S., Wallace, A.L.C. and Bassett, J.M., 1966. Metabolic effects of ovine growth hormone in sheep. J. Endocrinol., 35: 341-353. Wolfrom, G.W., Ivy, R.E. and Baldwin, C.D., 1985. Effects of growth hormone alone and in combination with RALGRO (Zeranol) in lambs. J. Anim. Sci., 61 (Suppl 1): 249-250 (Abstr). Wynn, P.C., Wallace, A.L.C., Kirby, A.C. and Annison, E.F., 1988. Effects of growth hormone administration on wool growth in Merino sheep. Aust. J. Biol. Sci., 41: 177-187 Zainur, A.S., Tassell, R., Kellaway, R.C. and Dodemaide, W.R., 1989. Recombinant growth hormone in growing lambs: Effects on growth, feed utilization, body and carcass characteristics and on wool growth. Aust. J. Agric. Res., 40:195-206.
RESUME Spencer, G.S.G., Schurmann, A., Berry, C., Wolff, J.E., Napier, J.R., Hodgkinson, S.C. et Bass, J.J. 1994. Comparaison des effets de la r6combinaison somatotrophine bovine, ovine et porcine sur la croissance, l'efficacit6 et les charact6ristiques de la carcasse des agneaux. Livest. Prod. Sci., 37:311-321 (en anglais). Les effets d'une administration journali6rement de la somatotrophine ovine produite par recombinaison genetique (oGH) sur la croissance, l'efficacit6 alimentaire et de la composition de la carcasse ont 6t6 etudi6s dans les jeunes agneaux et les effets ont 6t6 compar6s avec ceux qui ont 6t6 obtenus avec une administration similaire de somatotrophine (GH) porcine (p) ou bovine (b). Quarante huite agneaux femelle de la race Coopworth ont 6t6 616v6s au r6gime qui consistait enti6rement de boulettes d'aliments et h l'age de 16 semaines ils ont 6t6 assign6s ~ Fun des quatre groupes, consistant chacun de 12 animaux. Chaque agneau a regu une injection s.c. journalibrement de soit oGH, bGH, pGH (0.1 mg/kg) ou d'un v6hicule. La ration alimentaire fut m6suree journali6rement et les poids vifs furent mesur6s hebdomadairement durant quatre semaines aprbs quoi les agneaux furent abattus pour mesurer les charact6ristiques de la carcasse et les poids des organes. Aussi bien les agneaux trait6s h I'oGH que ceux trait6s h la bGH grandirent plus rapidement que les t6moins ( P < 0.01 ) et leur carcasse 6tait plus lourde ~ l'abattage, Aucune difference significative avec les animaux de contr61e ne pouvait 6ire discern6e pour chaque groupe trait6 en ce qui concerne la ration alimentaire ou l'appetit, mais les agneaux trait6s/l I'oGH et la bGH avaient une efficacit6 alimentaire meilleure ( P < 0.01 ). A l'exception de la r6duction d'adiposit6 de la carcasse ( P < 0.01 ) pour les agneaux trait6s ~ la bGH, aucun effet majeur du traitement GH ne pouvait 6tre detecte sur la croissance de la laine ni sur les charact6ristiques de la carcasse. Aussi bien le traitement h I'oGH que celui ~ la bGH ont r6sult6 dans un accroissement des niveaux d'IGF-1 du plasma ( P < 0.01 ) en comparaison avec les t6moins et les agneaux trait6s a la pGH. Tousles agneaux trait6s a la GH ont produit des anticorps contre la GH dolt ils avaient 6t6 inject6e.
EFFECTS OF GROWTH HORMONES
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KURZFASSUNG Spencer, G.S.G., Schurmann, A., Berry, C., Wolff, J.E., Napier, J.R., Hodgkinson, S.C. und Bass, J.J., 1994. Vergleich der Wirkungen des Bovine-, Ovine und Porcine- rekombinantes Somatotropins auf dem Wachstum, der Leistungsf~ihigkeit und den Eigenschaften des Lammrumpfes. Livest. Prod. Sci., 37:311-321 (auf englisch). Die Wirkungen von t~iglichem Geben von rekombinantem ovine Somatotropin (oGH) auf dem Wachstum, der Futterverwertung und der Rumpfbildung der j ungen L/immern wurde studiert und die Wirkungen verglichen mit denen erreicht durch gleiches Geben von porcinem (p) oder bovinem (b) Somatotropin ( G H ) . Acht und vierzig weibliche Coopworth L/immer wurden g~inzlich mit Kiigelchen em~ihrt und im Alter von 16 Wochen wurden sie eine der 4 Gruppen von je 12 Tieren zugeteilt. Jedes Lamm erhielt t~iglich eine s.c. Injektion von entweder oGH, bGH, pGH (0.1 mg/kg) oder ein Vehikel. Futtereinnahme wurde t~iglich gemessen und lebendes Gewicht w~Schentlich gewogen ftir 4 Wochen danach wurden die L~immer geschlachtet um Rumpfeigenschaften zu messen und damit die Organe gewogen werden konnten. Sowohl oGH- wie bGH- behandelte L~immer hatten einen schnelleren Wuchs als die Kontrollen (P < 0.01 ) und beim Schlaten gr6sseres Rumpfgewicht. Kein grosser Unterschied wurde wahrgenommen zwischen kontrolle Tieren und behandelte Gruppen was Nahrungseinnahme oder relativer Appetit betrifft, aber oGH- und bGH- behandelte L~immer hatten eine bessere Futterverwetung ( P < 0.01 ). Mit der Ausnahme von geringerem Rumpffest ( P < 0.01 ) der bGHbehandelten Lammer, konnten keine besondere Auswirkunger auf das Wollwachstum oder die Rumpfeigenschaften festgestellt werden. Beide oGH- und bGH-Behandlungen gaben erh6hte Plasma Stuffen yon IGF-1 (P<0.01) in Vergleich zu den Kontrollen und pGH-behandelten L~immern. Alle GH-behandelte L~immer machten Antik6rper gegen den eingespritzen GH.
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Comparison of the effects of recombinant ovine, bovine and porcine growth hormones on growth, efficiency and carcass characteristics in lambs G . S . G . S p e n c e r , A. S c h u r m a n n , C. B e r r y , J.E. Wolff, J.R. N a p i e r , S.C. H o d g k i n s o n a n d J.J. Bass Growth Physiology, Ruakura Agricultural Centre, Hamilton, New Zealand (Accepted 28 May 1993 )
ABSTRACT The effects of daily administration of recombinantly derived ovine growth hormone (oGH) on live weight gain, food conversion and carcass composition were studied in young lambs and the effects compared with those obtained by administration of porcine (p) or bovine (b) growth hormone (GH). Forty-eight female Coopworth lambs were reared on a complete pelleted diet and, at 16 weeks of age, were allocated to one of four treatment groups. Each lamb received a daily s.c. injection of either oGH, bGH, pGH (0.1 mg/kg bodyweight) or vehicle. Food intake was measured daily and liveweights were measured weekly for 4 weeks after which the lambs were slaughtered for measurement of carcass characteristics and organ weights. Both the oGH- and bGH-treated lambs grew faster than controls (P<0.01) and had heavier carcasses at slaughter. No significant difference from control animals could be found for any treatment group with respect to food intake or relative appetite, but the oGH- and bGH-treated lambs had a better food conversion efficiency (P< 0.001 ). With the exception of reduced carcass fatness (P< 0.01 ) for bGH-treated lambs, no major effect of GH treatment could be detected on wool growth or carcass characteristics. Both oGH and bGH treatment resulted in increased plasma concentrations of IGF-1 (P<0.01) compared with controls and pGH-treated lambs. All GH-treated Iambs produced antibodies against the GH with which they were injected. Key words: Lambs; Growth hormone; Performance; IGF-1
INTRODUCTION Experiments on the administration of exogenous growth hormone (GH) h a v e p r o d u c e d i n c o n s i s t e n t e f f e c t s o n w e i g h t g a i n i n l a m b s ( S p e n c e r , 1 9 8 7 ). Administration of pituitary-derived ovine (o) GH to lambs has sometimes r e s u l t e d i n i n c r e a s e d w e i g h t g a i n ( W a g n e r a n d V e e n h u i z e n , 1978 ), w h i l e o n o t h e r o c c a s i o n s n o s t i m u l a t i o n o f g r o w t h h a s b e e n o b s e r v e d ( W h e a t l e y et al.,
Correspondence to: G.S.G. Spencer, Growth Physiology, Ruakura Agricultural Centre, Private Bag, Hamilton, New Zealand,
0301-6226/94/$07.00 © 1994 Elsevier Science B.V. All rights reserved. SSDI 0 3 0 1 - 6 2 2 6 ( 9 3 ) E 0 0 5 8 - Z
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1966; Muir et al., 1983 ). Possibly this inconsistency is a result of differences in experimental conditions, such as nutrition (MacRae et al., 1991 ), and it has been suggested that the protein anabolic response may be a better measure of GH efficacy. Reports on the effects of various GH preparations on indicators of the integrated protein anabolic response, such as carcass composition, and on food conversion efficiency (FCE) have been more consistent (Spencer, 1987; McBride and Moseley, 1991 ). The amino acid sequence of ovine and bovine (b) GH are similar (Warwick et al., 1989 ) and administration of bGH, of both pituitary (Wolfrom et al., 1985; Butler-Hogg and Johnsson, 1987; Rosemberg et al., 1989) and recombinantly derived sources (Johnsson et al., 1987; Sinnett-Smith et al., 1989; Zainur et al., 1989), has resulted in effects on growth and carcass composition similar to those found using pituitary-derived oGH. At the time this study commenced, there were no reports on the efficacy of recombinantly-produced porcine (19) GH or oGH on performance characteristics in lambs. After the start of this study, McLaughlin et al. ( 1991 ) reported a trial with recombinant pGH in lambs, but to date there have been no reports of the use of recombinant oGH in any species. The recent availability of adequate quantities of recombinant oGH, together with recombinant bGH and pGH, has allowed the present study on the comparative effectiveness of these three growth hormones on growth, food intake, food conversion efficiency and carcass characteristics of growing lambs. MATERIALSAND METHODS
Growth hormone preparations Recombinant bGH (Lot 7368C-91 X) was a gift from American Cyanamid Co. (Princeton, New Jersey, USA). Recombinant pGH and oGH were provided by Bunge (Australia) Pty.Ltd. (Melbourne, Australia). Following repurification, all three growth hormones consisted primarily of a monomeric GH peak on fast protein liquid chromatography (FPLC) with little evidence ofdimers. All GH preparations were tested in a bioassay to assess their ability to stimulate growth. Each day, for 6 days, 2 mg/kg bodyweight of the preparations were injected subcutaneously in a strain of GH-deficient rats (Charlton et al., 1988 ). All three preparations stimulated a significant increase in liveweight gain with no differences amongst the preparations (Fig. 1 ). Animals Forty-eight female Coopworth crossbred lambs were used. The lambs were weaned from the ewes at 8 weeks of age and then fed on a lucerne-barley pelleted diet (60% lucerne, 30% barley, 5% linseed oil, 5% molasses; providing 17.5% crude protein and 10 MJ/kg DM metabolisable energy). The lambs
EFFECTSOF GROWTHHORMONES
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Fig. 1. Body weight of growth hormone-deficient dwarf rats both before and after treatment with: saline, or 2 m g / k g per day of oGH, b G H or p G H by subcutaneous injection. Values are means _+SEM with n = 6 in each group. ** controls differ significantly ( P < 0.01 ) from all other groups.
were housed in individual adjacent pens with ad lib. access to food and water throughout the trial. All lambs were completely acclimatized to the diet and the housing conditions by the start of the experiment. At 16 weeks of age ( _ 3 days) the lambs were weighed prior to the start of treatment and allocated to one of four groups. The mean pre-treatment weight was 22.8_+0.22 kg and lambs were allocated to treatment groups such that both mean growth velocity in the preceding week, and initial mean weights were similar. Treatment consisted of daily subcutaneous injections of either: 0.1 m g / k g per day o f b G H , p G H or oGH, or a similar volume (0.5 ml) of alkaline saline vehicle. The animals were weighed weekly and the doses adjusted each week on the basis of the mean weight of the group. A new batch of each GH solution was prepared each day. A weighed amount of food (in substantial excess of predicted requirement) was offered to each lamb daily and refusals for each lamb were measured daily. After 4 weeks of treatment food was withheld from the lambs overnight prior to slaughter. The liver, kidney and thymus were removed at evisceration and weighed. Hot carcasses were weighed and dressing percentage calculated. Carcass lengths (from the base of the gambrel to the anterior of the brisket) were measured and the carcasses were then chilled overnight and quartered at the tenth rib. Rib-eye measurements (width, length and area) were made and half the carcass was frozen, minced and analysed for chemical composition (Kirton et al., 1962). Mid-side 10 cm 2 wool-patch clips were taken both before and after treatment as an measure of wool growth.
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Endocrine and immune responses Blood was collected by jugular venepuncture each week and the plasma separated for storage at - 20°C. Plasma insulin-like growth factor-1 (IGF-I) concentrations were measured by radioimmunoassay (Hodgkinson et al., 1991 ) following dissociation from binding proteins using acid-ethanol cryoprecipitation. Radiolabelled preparations of the bGH, oGH and pGH were made using the Iodogen method (Salacinski et al., 1981 ) as previously described (Spencer et al., 1991 ). These tracers were used to detect the presence in the plasma of antibodies to the growth hormones. The antibodies were assessed by incubating the sera at various dilutions to determine the dilution that bound 50% of added label. These dilutions (between 1:5 and 1: 10) were then used in a radioimmunoassay (Spencer et al., 1991 ), but using a 6% polyethylene glycol separation system and a standard curve of 0 - 64000 ng/ml of the appropriate GH preparation. Antibody binding capacity and affinity were estimated using Scatchard analysis on plasma samples obtained during the fourth week of the experiment. Statistical analyses All data (except antibody results) were analysed by ANOVA with co-variate adjustment for initial body weight or carcass weight for pre- and postmortem measurements, respectively. RESULTS
Growth and carcass characteristics The growth responses to the various treatments are summarized in Table 1. There was no significant difference in growth rate between bGH and oGH. Both treatments, however, resulted in significantly faster growth than that observed in control lambs (38% and 26% greater, respectively). There was no difference between the growth rates of pGH-treated and control lambs. The increased liveweight was reflected in heavier carcass weights in the oGH- and bGH-treated animals, significantly so ( P < 0.05 ) in the latter group, but there were no differences among the treatment groups with respect to measurements of carcass length or rib-eye dimensions, when adjusted for carcass weight (Table 2 ). Liver weight was significantly greater ( P < 0.01 ) in the bGH-treated animals, while kidney weight was lower ( P < 0.05 ) in the pGHtreated lambs. Chemical composition analyses revealed that the bGH-treated animals had a lower proportion of body fat ( P < 0.01 ) and increased water ( P < 0.05 ) compared with controls, but no differences were found in carcass composition among the controls, oGH or pGH groups. There was no significant effect of oGH, bGH or pGH on wool growth.
EFFECTS OF GROWTH HORMONES
315
TABLE 1 Weekly live weight, average daily food intake ~, relative appetite (intake/weight) and overall food conversion efficiency (FCE: Weight gain/food intake) in lambs treated for 4 weeks with either vehicle, oGH, b G H or pGH 2 Trait
Weight (kg) Week 0 Week 1 Week 2 Week 3 Week 4 Food intake, g / d Appetite, g intake/g weight FCE
Treatment Control
oGH
bGH
pGH
sed
23.0 24.2 26.6 28.2 29.5 1341 51 0.17
22.9 25.0 a 27.8 b 29.5 c 31.2 c 1448 53 0.21 c
22.9 25.0 a 27.9 b 30.2 c 32.1 c 1373 50 0.24 c
22.2 24.4 26.7 28.1 29.5 1305 50 0.18
0.65 0.31 0.43 0.43 0.46 79 2.7 0.01
ap< 0.05, bp< 0.01, cp< 0.001 compared with control values. ~Food intake is air-dried weight (approximately 88% DM). 2Food intake, appetite and FCE are adjusted for initial live weight.
TABLE 2 Carcass dissection and chemical composition analyses of Iambs treated over 4 weeks with either vehicle, oGH, b G H or pGH Trait
Live weight, kg Hot carcass weight, kg Dressing, % Liver, g Kidney, g Kidney fat, g Thymus, g Ribeye area, cm 2 Carcass length, m m Femur length, m m Tibia length, ram Carcass fat, % Carcass water, % Carcass ash, % Carcass protein, % Wool weight, g/10 cm 2 skin
Treatment
pooled sed
Control
oGH
bGH
pGH
27.6 13.0 47.1 529 94 184 49 10.57 874 247 174 23.0 56.1 4.0 17.0 5.68
28.3 13.5 47.7 556 90 210 56 11.16 876 240 171 23.3 56.0 3.7 17.1 5.19
29.5 b 13.8 a 46.8 581 b 95 197 53 11.21 897 245 174 20.1 b 58.0 a 4.2 17.8 5.89
27.0 12.8 47.4 489 85 a 189 43 10.57 879 248 175 22.6 56.2 4.0 17.2 5.17
ap< 0.05, bp< 0.01 compared with control values.
0.74 0.39 0.67 24.4 3.5 18.5 5.1 0.51 12 5.1 3.5 0.9 0.7 0.2 0.3 0.12
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TABLE 3
Plasma concentrations o f IGF-1 ( n m o l / L ) during daily treatment with either vehicle, o G H , b G H or pGH I
Treatment
Week Week Week Week
1 2 3 4
Control
oGH
bGH
pGH
24.1 _+ 1.9 23.1 _+ 1.9 16.5_+0.5 14.0-+ 0.8
30.8_+ t.0 a 27.1 + 1.5 20.1 + 0 . 9 a 17.9_+ 1.9 a
29.2_+ 1.9 36.3-+ 1.3 b 22.8-+ 1.0 b 20.1 _+ 1.3 a
23.7_+0.6 24.0_+3.0 16.7_+0.6 13.4_+0.5
ap < 0.01, cp < 0.001 compared with control values. ~Values are means -+ SEM. TABLE4
Mean ( _+S E M ) antibody capacity and affinity in lambs following 4 weeks of daily treatment with o G H , b G H or p G H Item
Binding capacity, mol/1 Binding affinity, 1/mol
Treatment oGH
bGH
pGH
1.01 _+0.18X 10 -7 5.10_+0.76)< 106
1.61 + 0 . 5 7 × 10 - t ° 2.17_+0.48)< 10 ~°
2 . 4 8 + 0 . 6 7 × 10 -~° 1.21 _+0.49× 10 ~°
Food intake and conversion There were no differences among the treatment groups with respect to average daily food intake (ADFI) and relative appetite (ADFI/kg liveweight). However, food conversion efficiency (FCE; weight gain/kg food intake) was enhanced in the oGH and bGH groups compared with the controls (Table
1). Endocrine and immune responses Growth hormone treatment was associated with increased plasma IGF-1 concentrations in the oGH and bGH groups compared with the control and pGH groups (Table 3). Significant binding of radiolabelled oGH, bGH or pGH was observed only in the plasma of GH-treated lambs (Table 4 ). DISCUSSION
The use of recombinantly-derived oGH has not been previously reported, and the results of this experiment indicate that recombinant oGH is able to stimulate an increase in plasma IGF-1, growth rate and FCE when given to lambs.
EFFECTS OF GROWTH HORMONES
317
The growth-stimulating effect of recombinant bGH administration on growth rate of lambs concurs with results reported by most (Pullar et al., 1986; Zainur et al., 1989; McLaughlin et al., 1991 ) but not all workers (Johnsson et al., 1987; Sinnett-Smith et al., 1989; Sun et al., 1992 ). It has been suggested that the plane of nutrition (particularly with regard to protein) may be an important factor in the response of pigs to GH (Etherton, 1989 ). In the present study the lambs were fed ad lib. with a relatively high protein diet and this may have influenced the positive effect of bGH. However, the relationship between orally ingested protein and amino acid absorption in ruminants is far from clear (Clarke et al., 1966). The effect ofbGH in improving FCE and decreasing carcass fatness in sheep has been consistent, and the results of the present study are similar to those previously reported. The lack of effect of bGH on wool growth is in agreement with a recently published report (Sun et al., 1992 ) in which a similar dose of recombinant bGH was used. There is, however, no general consensus on the effects of exogenous GH treatment on wool growth. Some workers have reported increased wool growth (e.g., Johnsson et al., 1987) while others reported decreased wool growth with GH administration (e.g., Wynn et al., 1988 ). It has also been reported that wool growth increases following cessation of GH treatment (Wynn et al, 1988 ), though such measurements could not be made in the present study. The lack of effect of recombinant pGH on growth rate of lambs is in agreement with the contemporary study by McLaughlin et al. ( 1991 ). This is not due to an inherent biological inactivity in this pGH preparation, since it was able to stimulate growth in a GH-deficient strain of dwarf rats. The lack of effect of pGH on growth rate in lambs is mirrored by its lack of effect on plasma IGF- 1 concentrations and, indeed, no effect on any aspect of carcass composition or food utilization. These results indicate that the pGH, although showing 91% sequence homology with oGH was not able to bind sufficiently to the oGH receptor to elicit a measurable response. McLaughlin et al. ( 1991 ) reported antibody titres to pGH at an early stage of treatment, and argued that it was the appearance of these antibodies that reversed the apparent, yet transient, effect of pGH on lamb growth noted in their study. However, in the present study, pGH had no effect on growth even in the first week of treatment, indicating that the inability of pGH to stimulate growth in Iambs is more likely to be due to a lack of binding to the oGH receptor, rather than as a consequence of antibody production; a contention supported by the positive effects of both oGH and bGH, although they also produced antibodies. All lambs produced antibodies against the GH preparations, but in all cases the affinities were low when compared with the affinity of either the high affinity ( 1013 L / m o l ) or the low affinity ( 1012 L/mol) GH receptor in sheep (Breier et al., 1987 ). Plasma from lambs given oGH showed a very low affin-
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ity, but relatively high capacity, binding of tracer compared with the pGHand bGH-treated lambs. It seems unlikely that this reflects a higher production of antibody to the oGH than to the other GH preparations, but may indicate the presence of a circulating oGH binding protein (Davis et al., 1992). There has generally been much inconsistency among studies in response to GH administration, particularly in ruminant species. Some of the problems (e.g. nutrition) associated with this variability have been discussed, but the use of heterologous preparations has also been suggested as a reason for this unpredictability (Chung et al., 1985 ). The similarity of the growth and plasma IGF-1 responses following bGH and oGH administration to lambs confirms the indication obtained from studies using pituitary-derived ovine and bovine growth hormones that bGH is equipotent to oGH in lambs. There appears to be an association between plasma IGF-1 response to GH administration and the growth rates in the different groups. The greater liver weight in the oGH- and bGH-treated lambs may have had a role in the increased IGF- 1 concentrations in these lambs, but whether the increased IGF1 caused, or resulted from these changes is not clear. In conclusion, this study reports, for the first time, the use of recombinantly-derived oGH to increase growth rate and FCE in lambs. It also confirms that daily injection of bGH can stimulate growth, carcass leanness and FCE in lambs and indicates that recombinant oGH and bGH are equipotent in lambs. By contrast, pGH had no effect on any aspect of performance studied. ACKNOWLEDGEMENTS
We are grateful to H. Burrill of Bunge (Australia) Pty. Ltd. for the gift of recombinant oGH and pGH and to Dr A.J. Mudd of American Cyanamid for the bGH. We also thank Dr Neil Cox for statistical analysis of the data.
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Bloch, B.A., 1988. Growth hormone deficient dwarfism in the rat: a new mutation. J. Endocrinol., 119: 51-58. Chung, C.S., Etherton, T.D. and Wiggins, J.P., 1985. Stimulation of swine growth by porcine growth hormone. J. Anim. Sci., 60:118-130. Clarke, E.M.W., Ellinger, G.M. and Phillipson, A.T., 1966. The influence of diet on the nitrogenous components passing to the duodenum and through the lower ileum of sheep. Proc. Roy. Soc.(B), 166: 63-79. Davis, S.L., Graf, M., Morrison, C.A., Hall, T.R. and Swift, P.J., 1992. Identification and partial purification of serum growth hormone binding protein in domestic animal species. J. Anim. Sci., 70: 773-780. Etherton, T.D., 1989. The mechanisms by which porcine growth hormone improves pig growth performance. In: R.B. Heap, C.G. Prosser and G.E. Lamming (Editors), Biotechnology in Growth Regulation. Butterworths. London. pp 97-105. Hodgkinson, S.C, Bass, J.J. and Gluckman, P.D., 1991. Insulin-like growth factor binding proteins in sheep: effect of recombinant growth hormone and nutritional status. Domest. Anim. Endocrinol., 8:345-351. Johnsson, I.D., Hathorn, D.J. Wilde, R.M., Treacher, T.T. and Butler-Hogg, B.W., 1987. The effects of dose and method of administration of biosynthetic somatotropin on live-weight gain, carcass composition and wool growth in young lambs. Anim. Prod., 44: 405-414. Kirton, A.H., Barton, B.A. and Rae, A.C., 1962. The efficiency of determining chemical composition of lamb carcasses. J. Agric. Sci., 58:381-386. MacRae, J.C., Bruce, L.A., Hovell, F.D.DeB., Hart, I.C., Inkster, J., Walker, A. and Atkinson, T., 1991. Influence of protein nutrition on the response of growing lambs to exogenous bovine growth hormone. J. Endocrinol., 130:53-61. McBride, B.W. and Moseley, W.M., 1991. Influence of exogenous somatotropin on the components of growth in ruminants. In: P. van der Wal, G.M. Weber and F.J. van der Wilt (Editors), Biotechnology for control of growth and product quality in meat production: implications and acceptability. Pudoc. Wageningen. pp 91-103. McLaughlin, C.L., Rogan, G.J., Buonomo, F.C., Cole, W.J., Hartnell, G.F., Hudson, S., Kasser, T.R., Miller, M.A. and Baile, C.A., 1991. Finishing lamb performance responses to bovine and porcine somatotropins administered by Alzet minipumps. J. Anim. Sci., 69: 4039-4048. Muir, L.A., Wien, S., Duquette, P.F., Rickes, E.L. and Cordes, E.H., 1983. The effects of exogenous growth hormone and diethylstibestrol on growth and carcass composition of growing lambs. J. Anim. Sci., 56: 1315-1323. Pullar, R.A., Johnsson, I.D.and Chadwick, A.M.C., 1986. Recombinant bovine somatotropin is growth-promoting and lipolytic in fattening lambs. Anim Prod., 42:433-434 (Abstr). Rosemberg, E., Thonney, M.L. and Butler, W.R., 1989. The effects of bovine growth hormone and thyroxine on growth rate and carcass measurements in lambs. J. Anim. Sci., 67: 33003312. Salacinski, P.R.P., McLean, C., Sykes, J.E.C., Clement-Jones, V.V. and Lowry, P.J., 1981. lodination of proteins, glycoproteins and peptides using a solid-phase oxidising agent 1,3,4,6tetrachloro-3a,6ct diphenyl glycoluril (Iodogen) Anal. Biochem., 117:136-146. Sinnett-Smith, P.A., Woolliams, J.A., Warriss, P.D. and Enser, M., 1989. Effects of recombinant DNA-derived bovine somatotropin on growth, carcass characteristics and meat quality in lambs from three breeds. Anim. Prod., 49:281-289. Spencer, G.S.G., 1987. Biotechnology in the potential practical application of somatotrophic hormones for improving animal performance. Reprod. Nutr. Develop., 27B: 581-589. Spencer, G.S.G., Bass, J.J. Hodgkinson, S.C., Edgley, W.H.R and Moore, L.G., 1991. Effect of intracerebroventricular injection of IGF-1 on circulating growth hormone concentrations in the sheep. Domest. Anim. Endocrinol., 8:155-160. Sun, Y.X., Michel, A., Wickham, G.A., McCutcheon, S.N., 1992. Wool follicle development,
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wool growth and body growth in lambs treated from birth with recombinantly derived bovine somatotrophin. Anim. Prod., 55: 73-78. Wagner, J.F. and Veenhuizen, E.L., 1978. Growth performance, carcass deposition and plasma hormone levels in wether lambs when treated with growth hormone and thyroprotein. J. Anim. Sci., 47 (Suppl 1 ): 397 (Abstr). Warwick, J.M., Wallis, O.C. and Wallis, M., 1989. Cloning, sequence and expression in Escherichia coli of cDNA for ovine pregrowth hormone. Biochim. Biophys. Acta, 1008: 247-250. Wheatley, I.S., Wallace, A.L.C. and Bassett, J.M., 1966. Metabolic effects of ovine growth hormone in sheep. J. Endocrinol., 35: 341-353. Wolfrom, G.W., Ivy, R.E. and Baldwin, C.D., 1985. Effects of growth hormone alone and in combination with RALGRO (Zeranol) in lambs. J. Anim. Sci., 61 (Suppl 1): 249-250 (Abstr). Wynn, P.C., Wallace, A.L.C., Kirby, A.C. and Annison, E.F., 1988. Effects of growth hormone administration on wool growth in Merino sheep. Aust. J. Biol. Sci., 41: 177-187 Zainur, A.S., Tassell, R., Kellaway, R.C. and Dodemaide, W.R., 1989. Recombinant growth hormone in growing lambs: Effects on growth, feed utilization, body and carcass characteristics and on wool growth. Aust. J. Agric. Res., 40:195-206.
RESUME Spencer, G.S.G., Schurmann, A., Berry, C., Wolff, J.E., Napier, J.R., Hodgkinson, S.C. et Bass, J.J. 1994. Comparaison des effets de la r6combinaison somatotrophine bovine, ovine et porcine sur la croissance, l'efficacit6 et les charact6ristiques de la carcasse des agneaux. Livest. Prod. Sci., 37:311-321 (en anglais). Les effets d'une administration journali6rement de la somatotrophine ovine produite par recombinaison genetique (oGH) sur la croissance, l'efficacit6 alimentaire et de la composition de la carcasse ont 6t6 etudi6s dans les jeunes agneaux et les effets ont 6t6 compar6s avec ceux qui ont 6t6 obtenus avec une administration similaire de somatotrophine (GH) porcine (p) ou bovine (b). Quarante huite agneaux femelle de la race Coopworth ont 6t6 616v6s au r6gime qui consistait enti6rement de boulettes d'aliments et h l'age de 16 semaines ils ont 6t6 assign6s ~ Fun des quatre groupes, consistant chacun de 12 animaux. Chaque agneau a regu une injection s.c. journalibrement de soit oGH, bGH, pGH (0.1 mg/kg) ou d'un v6hicule. La ration alimentaire fut m6suree journali6rement et les poids vifs furent mesur6s hebdomadairement durant quatre semaines aprbs quoi les agneaux furent abattus pour mesurer les charact6ristiques de la carcasse et les poids des organes. Aussi bien les agneaux trait6s h I'oGH que ceux trait6s h la bGH grandirent plus rapidement que les t6moins ( P < 0.01 ) et leur carcasse 6tait plus lourde ~ l'abattage, Aucune difference significative avec les animaux de contr61e ne pouvait 6ire discern6e pour chaque groupe trait6 en ce qui concerne la ration alimentaire ou l'appetit, mais les agneaux trait6s/l I'oGH et la bGH avaient une efficacit6 alimentaire meilleure ( P < 0.01 ). A l'exception de la r6duction d'adiposit6 de la carcasse ( P < 0.01 ) pour les agneaux trait6s ~ la bGH, aucun effet majeur du traitement GH ne pouvait 6tre detecte sur la croissance de la laine ni sur les charact6ristiques de la carcasse. Aussi bien le traitement h I'oGH que celui ~ la bGH ont r6sult6 dans un accroissement des niveaux d'IGF-1 du plasma ( P < 0.01 ) en comparaison avec les t6moins et les agneaux trait6s a la pGH. Tousles agneaux trait6s a la GH ont produit des anticorps contre la GH dolt ils avaient 6t6 inject6e.
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KURZFASSUNG Spencer, G.S.G., Schurmann, A., Berry, C., Wolff, J.E., Napier, J.R., Hodgkinson, S.C. und Bass, J.J., 1994. Vergleich der Wirkungen des Bovine-, Ovine und Porcine- rekombinantes Somatotropins auf dem Wachstum, der Leistungsf~ihigkeit und den Eigenschaften des Lammrumpfes. Livest. Prod. Sci., 37:311-321 (auf englisch). Die Wirkungen von t~iglichem Geben von rekombinantem ovine Somatotropin (oGH) auf dem Wachstum, der Futterverwertung und der Rumpfbildung der j ungen L/immern wurde studiert und die Wirkungen verglichen mit denen erreicht durch gleiches Geben von porcinem (p) oder bovinem (b) Somatotropin ( G H ) . Acht und vierzig weibliche Coopworth L/immer wurden g~inzlich mit Kiigelchen em~ihrt und im Alter von 16 Wochen wurden sie eine der 4 Gruppen von je 12 Tieren zugeteilt. Jedes Lamm erhielt t~iglich eine s.c. Injektion von entweder oGH, bGH, pGH (0.1 mg/kg) oder ein Vehikel. Futtereinnahme wurde t~iglich gemessen und lebendes Gewicht w~Schentlich gewogen ftir 4 Wochen danach wurden die L~immer geschlachtet um Rumpfeigenschaften zu messen und damit die Organe gewogen werden konnten. Sowohl oGH- wie bGH- behandelte L~immer hatten einen schnelleren Wuchs als die Kontrollen (P < 0.01 ) und beim Schlaten gr6sseres Rumpfgewicht. Kein grosser Unterschied wurde wahrgenommen zwischen kontrolle Tieren und behandelte Gruppen was Nahrungseinnahme oder relativer Appetit betrifft, aber oGH- und bGH- behandelte L~immer hatten eine bessere Futterverwetung ( P < 0.01 ). Mit der Ausnahme von geringerem Rumpffest ( P < 0.01 ) der bGHbehandelten Lammer, konnten keine besondere Auswirkunger auf das Wollwachstum oder die Rumpfeigenschaften festgestellt werden. Beide oGH- und bGH-Behandlungen gaben erh6hte Plasma Stuffen yon IGF-1 (P<0.01) in Vergleich zu den Kontrollen und pGH-behandelten L~immern. Alle GH-behandelte L~immer machten Antik6rper gegen den eingespritzen GH.