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Lealiifano A.K.,Rivalea Australia Pty. Ltd. | Pluske J.R.,Murdoch University | Nicholls R.R.,Animal Research and Development | Dunshea F.R.,University of Melbourne | And 5 more authors.
Journal of Animal Science | Year: 2011

The objective of this study was to evaluate whether altering the timing of the secondary antigonadotropin- releasing factor (GnRF) immunization closer to slaughter in male finishing pigs would reduce the increase in P2 fat depth (6.5 cm from the midline over the last rib), while still limiting the incidence of boar taint. Entire male pigs are immunized against GnRF to reduce the concentration of testicular steroids that in turn limits the incidence of boar taint. Additionally, testicle measurements and color measurements were taken to examine whether they could be used to differentiate nonimmunized entire males from immunized male pigs. A total of 175 Large White × Landrace entire male pigs aged 16 wk (59 kg of BW) were used in a completely randomized design with 5 treatment groups based on the time that pigs received the secondary immunization before slaughter. Pigs were housed in groups of 7 and randomly allocated to 1 of 5 treatments with 5 replicates per treatment. The treatment groups were as follows: no secondary immunization before slaughter, and the secondary immunization given at 2, 3, 4, or 6 wk before slaughter. The P2 fat depth levels were reduced (P = 0.054) with the secondary immunization closer to slaughter (11.7, 11.3, 12.8, 12.6, and 13.7 mm for no secondary immunization, secondary immunization at 2, 3, 4, and 6 wk before slaughter, respectively). Androstenone concentration did not exceed the generally accepted industry sensory threshold of 1.0 μg/g of fat, and both androstenone concentration in the adipose tissue and testosterone concentrations in the blood were suppressed (P < 0.001) in all immunized pigs regardless of timing of the secondary immunization compared with pigs that did not receive the secondary immunization. Skatole concentration of all pigs in the experiment did not exceed the generally accepted industry sensory threshold of 0.2 μg/g. Testes weight was reduced (P < 0.001) with increased time between slaughter and the secondary immunization. Immunized pigs, regardless of time before slaughter, had greater L* (lightness) and b* (yellowness) color of the testicle surface (P < 0.001 and P = 0.020, respectively), and less a* (redness) color compared with entire males (P < 0.001). The study provides further evidence of the efficacy of the anti-GnRF immunization and indicates that the secondary immunization can be moved closer to slaughter, while still limiting the incidence of boar taint. Testicle measurements and color measurements together could provide a method of discrimination between carcasses from immunized entire males clear of boar taint and tainted carcasses. © 2011 American Society of Animal Science.


Heo J.M.,Murdoch University | Kim J.C.,Animal Research and Development | Hansen C.F.,Murdoch University | Hansen C.F.,Copenhagen University | And 5 more authors.
Livestock Science | Year: 2010

The interactive effects of dietary protein level, zinc oxide (ZnO) supplementation and experimental infection with enterotoxigenic E. coli (ETEC) on the incidence of post-weaning diarrhoea (PWD) and indices of protein fermentation were examined. Ninety-six, individually housed 21-day-old pigs were used in a split plot experiment, with the whole plot being challenge or no challenge with ETEC and the dietary treatments used as subplots and arranged in a completely randomised 2×2 factorial design, with the factors being (i) 2 dietary protein levels [251g/kg (high) vs. 192g/kg (low) crude protein] and (ii) addition or no addition of 2500ppm ZnO. Between days 1 and 14 after weaning, ETEC infection increased faecal consistency (FC; looser faeces) but only in pigs fed the high protein diet (P<0.05) or without ZnO (P<0.1). Pigs fed a high protein diet without ZnO showed more loose faeces (higher FC) compared to pigs fed either a high protein diet with ZnO supplementation or pigs fed lower protein diets without and with ZnO supplementation (P<0.05). Feeding either a low protein diet or ZnO decreased (P<0.05) PWD. Feeding a low protein diet decreased (P<0.001) plasma urea nitrogen (PUN) and faecal NH3-N contents. There were no 2- or 3-way interactions (P>0.05) between the independent variables for PWD, PUN and faecal NH3-N. The results indicate that feeding a low protein diet supplemented with amino acids or adding ZnO to either low or high protein diets could be used as dietary strategies to reduce PWD in piglets. © 2010 Elsevier B.V.


Heo J.M.,Murdoch University | Kim J.C.,Animal Research and Development | Hansen C.F.,Murdoch University | Hansen C.F.,Copenhagen University | And 3 more authors.
Animal Production Science | Year: 2010

The interactive effects of dietary protein level, zinc oxide (ZnO) supplementation and infection with an enterotoxigenic strain of Escherichia coli (ETEC) on performance responses and gastrointestinal tract characteristics were examined. Ninety-six individually housed, 21-day-old pigs (1:1 gender ratio) with initial bodyweight (BW) of 7.2 0.69 kg, were used in a split plot experiment, with the whole plot being challenge or no challenge with ETEC and the dietary treatments used as subplots and arranged in a completely randomised 2 2 factorial design, with the factors being (i) two dietary protein levels (251 versus 192 g/kg crude protein) and (ii) addition or no addition of 2.5 g/kg ZnO. No antibiotic was added to the diet. The ETEC infection decreased average daily gain (P 0.001) and increased feed conversion ratio (P 0.01). Protein level had no effect on performance of pigs while ZnO supplementation increased (P 0.001) average daily gain and average daily feed intake and hence decreased feed conversion ratio (P 0.001). There were no 2- or 3-way interactions for growth performance indices (P 0.05). Feeding a lower protein diet did not influence (P 0.05) faecal volatile fatty acid concentrations. In non-infected pigs, feeding a lower protein diet caused a lower pH in the jejunum and ileum compared with pigs fed a higher protein diet (P 0.05 and P 0.01, respectively). However, feeding ZnO-supplemented diets increased (P 0.05) the pH in the stomach and caecum compared with feeding diets without ZnO supplementation. Protein level did not alter (P 0.05) empty BW but dietary supplementation with ZnO increased empty BW (P 0.05). Neither protein level nor ZnO supplementation modified small intestinal morphology, although a tendency for an interaction (P 0.1) was detected for jejunal villous height between protein level and ZnO supplementation. The results indicate that feeding ZnO-supplemented diets improved pig performance, and feeding a lower protein diet without ZnO supplementation did not compromise performance nor modify measures of gastrointestinal tract structure and function compared with pigs fed a diet higher in protein after weaning. © CSIRO 2010.


Heo J.M.,Murdoch University | Kim J.C.,Animal Research and Development | Hansen C.F.,Murdoch University | Hansen C.F.,Copenhagen University | And 3 more authors.
Animal Feed Science and Technology | Year: 2010

This study evaluated possible nutritional and physiological mechanisms to explain why feeding a diet of decreased protein content reduces PWD. A total of 48 male pigs weaned at 21 d (initial BW 6.9±0.11kg; mean±SEM) was used in a 2×2×2 factorial arrangement of treatments with the respective factors being: (1) PL (HP 239g/kg vs. LP 190g/kg CP); (2) presence or absence of an ETEC challenge; and (3) duration of feeding after weaning until euthanasia (D; 7 d vs. 14 d). No dietary antimicrobial compounds were used, and diet LP contained crystalline AA including isoleucine and valine to achieve an ideal AA pattern. Pigs were offered the experimental diets on an ad libitum basis. Feeding a LP diet decreased total N intake, ileal N flow, PUN and NH3-N contents at the ileum and all sites in the large intestine (P<0.05-0.001), but did not alter (P>0.05) the AID of N and AA at either d 7 or d 14, except for serine which was lower in pigs fed the LP diet (P<0.001). Feeding diet HP increased the incidence of PWD, and ETEC infection increased PWD only in pigs fed the HP diet (PL×ETEC interaction, P<0.05). Pigs fed diet HP had more PWD at d 7 but not at d 14 after weaning (PL×D interaction, P<0.05). Experimental ETEC infection increased (P<0.001) faecal Escherichia coli score compared to non-infected pigs, and decreased AID of some AA at d 7 (ETEC×D interaction, P<0.05-0.001). Feeding diet LP reduced the molar proportion of BCFA in the caecum and proximal colon (P<0.001 and P<0.05, respectively), but total VFA concentrations in this organ were unaffected by PL (P>0.05). Pigs fed diet LP had decreased pH in the jejunum and ileum (P<0.05 and P<0.01, respectively), while ETEC infection increased pH in the caecum and proximal colon at d 7 (ETEC×D interaction, P<0.05). Feeding diet LP did not alter GIT weight, but ETEC infection adversely affected the proportional weight of the GIT at d 7 (ETEC×D interaction, P<0.01). The PL did not alter small intestinal morphology and growth. These results suggest that feeding a LP diet immediately after weaning reduces the flow of N into the large intestine, thereby decreasing protein fermentation without altering apparent AA digestibility at the ileum. © 2010 Elsevier B.V.


Heo J.M.,University of Manitoba | Heo J.M.,Murdoch University | Opapeju F.O.,University of Manitoba | Pluske J.R.,Murdoch University | And 3 more authors.
Journal of Animal Physiology and Animal Nutrition | Year: 2013

Summary: For the last several decades, antimicrobial compounds have been used to promote piglet growth at weaning through the prevention of subclinical and clinical disease. There are, however, increasing concerns in relation to the development of antibiotic-resistant bacterial strains and the potential of these and associated resistance genes to impact on human health. As a consequence, European Union (EU) banned the use of antibiotics as growth promoters in swine and livestock production on 1 January 2006. Furthermore, minerals such as zinc (Zn) and copper (Cu) are not feasible alternatives/replacements to antibiotics because their excretion is a possible threat to the environment. Consequently, there is a need to develop feeding programs to serve as a means for controlling problems associated with the weaning transition without using antimicrobial compounds. This review, therefore, is focused on some of nutritional strategies that are known to improve structure and function of gastrointestinal tract and (or) promote post-weaning growth with special emphasis on probiotics, prebiotics, organic acids, trace minerals and dietary protein source and level. © 2012 Blackwell Verlag GmbH.

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