Feed additives and feed efficiency in the pork industry F.R. Dunshea 1,2 1 CRC for High Integrity Pork; 2 Department of Agriculture and Food Systems, Melbourne School of Land and Environment, The University of Melbourne, Parkville, VIC 3010;

We need technology

Some technologies Porcine somatotropin (pST, Reporcin) β-agonists (ractopamine, Paylean) Dietary additives Cysteamine Chromium Betaine Neuroleptics Immunization against GnRF (Improvac) Beta agonists (ractopamine, Paylean) Orally active metabolic modifier

Metabolic modifiers Porcine somatotropin (pST, Reporcin) Recombinant peptide hormone Daily (or less frequent) injectable Beta agonists (ractopamine, Paylean) Orally active metabolic modifier

Introduction Wray-Cahen et al. 1998

Daily pST injections increases daily gain (data 16 farms across Australia) Dunshea 2005

Daily pST injections decreases FCR (data 16 farms across Australia) Dunshea 2005

MWF pST injections decreases FCR Hellams et al 2000

Metabolic modifiers Beta agonists (ractopamine, Paylean) Orally active metabolic modifier

Ractopamine increases daily gain (5 ppm for 14 d followed by 10 ppm for 17 d) Rikard-Bell et al. (2009a)

Ractopamine decreases feed:gain (5 ppm for 14 d followed by 10 ppm for 17 d) Rikard-Bell et al. (2009a)

Effect of feeding ractopamine for 4 weeks without or with daily pST for last 2 weeks on FCR Rikard-Bell et al. (2009b)

Paylean for 4 weeks plus 4 pST injections over last 2 weeks decreases feed:gain van Barneveld et al. (2009)

Introduction Wray-Cahen et al. 1998

Introduction Wray-Cahen et al Cysteamine

Cysteamine hydrochloride (CSH) increases ST secretion in rats Mechanism appears to be through inhibition of somatostatin (SRIF) secretion Responses are not as pronounced as pST and may be transitory Further work is required to optimise the dose and timing as high doses may blunt the response more rapidly through inhibition of gherelin

Cysteamine at 70 ppm increases ADG

Response to Cysteamine (70 ppm) is not as great as pST Dunshea 2007

Cysteamine (70 ppm) and pST decrease fat Dunshea 2007

Cysteamine Cysteamine hydrochloride (CSH) increases ST secretion in rats Mechanism appears to be through inhibition of somatostatin (SRIF) secretion Responses are not as pronounced as pST and may be transitory Further work is required to optimise the dose and timing as high doses may blunt the response more rapidly through inhibition of ghrelin

Introduction Wray-Cahen et al. 1998

GRF (GHRH) and other neonatal manipulations Gallagher 2000

Dunshea (unpublished) Neonatal treatment with pST can increase weaning weight and subsequent growth

Dunshea (unpublished) Neonatal treatment with pST can increase slaughter and carcass weight

Introduction Wray-Cahen et al Chromium

Chromium is an essential element that improves insulin activity The digestibility and availability of Cr is low and variable (0.5-2% for inorganic Cr and 10-25% for organic) Responses to dietary Cr have been variable, possibly because of poor and variable digestibility

Dietary Cr increases ADG but the response is variable (31 studies) Sales and Jancik 2011

Nano- and micro- chromium Chromium is an essential element that improves insulin activity The digestibility and availability of Cr is low and variable (0.5-2% for inorganic Cr and 10-25% for organic) Responses to dietary Cr have been variable, possibly because of poor and variable digestibility Reducing the Cr particle size may improve responses

Dietary Cr increases carcass weight Hung et al. 2011

Dietary Cr reduces backfat in very lean pigs Hung et al. 2011

Dietary nano CrPic increases the expression of muscle PI3K (an insulin signalling gene) Hung et al. 2011

Betaine Betaine is an osmoregulator that reduces maintenance energy requirements Improved pigs can be limited by DE intake Responses to metabolic modifiers may be limited by DE intake Betaine may provide additional energy for protein deposition in pigs

Betaine and pST have additive effects on daily gain in boars fed 80% ad libitum BetaineP=0.049 pSTP<0.001 a b c c Suster et al. (2006)

Betaine and xylanase have additive effects on daily gain in gilts fed 80% ad libitum (2.7 kg/d) Dunshea (unpublished)

Dietary neuroleptics may improve growth of boars Performance of group-housed entire males over the late finishing period is less than potential, possibly because of aggressive and sexual behaviours Dietary neuroleptics (and immunization against GnRF) offer a means of reducing sexual and aggressive behaviours

Dietary neuroleptics may increase carcass growth Dunshea et al. 2011

Physical castration of male pigs results in reduced feed efficiency and lean deposition and excess deposition of fat Performance of group-housed entire males over the late finishing period is less than potential, possibly because of aggressive and sexual behaviours Immunization against GnRF offers a means of reducing boar taint and negative behaviours and improving growth performance over that of both entire and physically castrated males Immunological castration ( Improvac )

Suster et al. (2006) Entire males deposit more lean than physically castrated barrows during finishing Entire Barrow

Physically castrated barrows are fatter than entire males at 150 days of age Suster et al. (2006)

Physically castrated barrows are less efficient than entire males (ca. 11%) from weaning to market

I Smell Boar Taint!

GnRF Hypothalamus Pituitary  LH & FSH  steroids such as testosterone & androstenone  boar taint & sexual & aggressive activities Testes Sexual development in the boar

GnRF Hypothalamus Pituitary  LH & FSH  steroids such as testosterone & androstenone  boar taint & sexual & aggressive activities Anti-GnRF Testes Immunization against GnRF (with Improvac) arrests/reverses sexual development in the boar

Immunocastration reduces testes size Dunshea et al. (2001) PrimarySecondary

Dunshea et al. (2008) Plasma testosterone declines rapidly and remains low for upto 8 weeks

Dunshea et al. (2008) Fat androstenone declines rapidly and remains low for upto 8 weeks

Castration and immunocastration eliminate boar taint Dunshea et al. (2001)

Dunshea et al. (2011)

Moore et al. (2011) Immunization agaisnt GnRF decreases the lysine requirement beyond 3 weeks after secondary immunization

pST and Improvac combine to increase daily gain Oliver et al. (2001)

Ractopamine and Improvac combine to increase daily gain Moore et al. (2008)

Conclusions We have some excellent metabolic modifiers (eg. pST and ractopamine) and we need to advocate their use while we continue to identify other technologies Dietary additives offer a means of manipulating growth performance but can be variable and inconsistent and further research is needed to identify the circumstances under which they are most effective. There may be opportunities to manipulate the somatotrophic/IGF/insulin axis with dietary additives (although responses will likely not match pST) Immunization against GnRF offers a means of improving feed efficiency through making use of entire males without the risk of boar taint