Combining a ractopamine feeding regime and porcine somatotropin has additive effects on finisher pig performance

Treatment of finisher pigs with dietary ractopamine (RAC; Paylean®, Elanco Animal Health, NSW) improves daily gain and feed efficiency commensurate with increased protein deposition in finishing pigs (Dunshea et al., 1993). However, effects of RAC on P2 fat deposition are equivocal. Dunshea et al. (1993) found no change in gilts and barrows, whilst a trend towards reduced P2 depth was observed in boars fed dietary RAC. Exogenous porcine somatotropin (pST; Reporcin®, OzBioPharm Pty Ltd, Victoria) improves daily gain and feed efficiency and increases the ratio oflean to fat in carcases of boars, gilts and barrows (Campbell et al., 1989). As both technologies are applied at the end of the finishing phase, it is of interest to determine whether a combination of RAC and pST has additive effects on pig performance

Increasing ractopamine levels in finisher pig diets improves growth performance in light, medium and heavy boars

The objective of this study was to determine the dose response to RAC in light, medium and heavy-weight boars

Good images, effective messages? Working with students and educators on academic practice understanding

Work at Northumbria University has focussed on activity that extends opportunities for students to engage directly with the skills development necessary for sound academic practice. This has included highly visual campaigns on the "Plagiarism trap", providing access to Turnitin plagiarism detection software, guides and sessions to highlight use of associated referencing tools. Sessions on a variety of topics, such as supporting study skills and reading originality reports, have been provided for students on taught, undergraduate and postgraduate programmes. This provision has included students working on collaborative partners' sites and also those on research programmes. Alongside the activities with students, "designing out" approaches have been embedded in staff development within the educator community at Northumbria. Formative use of Turnitin is integrated throughout programmes and academic practice development is formally recognised within the University Learning and Teaching Strategy's focus on information literacy. This article outlines and reviews these activities in a critical institutional context and evaluates responses from a variety of students and educators to determine how effective these measures have been

Responses of finisher boars and gilts to dietary lysine and ractopamine

The minimum total lysine requirement for pigs between 80 and 120 kg has been reported as 0.65g/kg (National Research Council, 1998) whilst the current recommended lysine requirements for pigs fed a diet supplemented with ractopamine (RAC) is 0.70g/kg of total lysine (approximately 0.56g available lysine/MJ digestible energy (DE)). More recently (Rikard-Bell et al., 2009) reported that the improvements in growth performance elicited by RAC were similar for pigs offered diets with 0.56 or 0.65 g available lysine/MJ DE. The aim of this experiment was to investigate the performance responses of finisher pigs offered a wider range of dietary lysine levels and three levels of dietary RAC

Effects of dietary lysine on growth responses of pigs to increasing doses of ractopamine

Commercial recommendations for dietary lysine specifications in diets for pigs supplemented with ractopamine (RAC) is 0.56 g available lysine/MJ digestible energy (DE; King et al., 2000). A recent study confirmed that when RAC supplemented diets are formulated to 0.56 g available lysine/MJ DE, growth rate and feed efficiency are improved (Dunshea et al., 2005), together with an increase in lean tissue deposition in both sexes, although fat deposition was reduced in boars and remained constant in gilts. The aim of this experiment was to determine whether the current dietary lysine recommendations are sufficient to optimize the response in feed efficiency (FCR), growth rate (ADG) and tissue deposition in boars and gilts offered high and low doses of RAC in diets

Ractopamine effects β-1 and β-2 adrenergic receptor gene expression in fat and muscle tissue of boars and gilts

The aim of the experiment was to determine the effect of RAC dose, duration of treatment, or sex effect on βAR gene subtype expression in fat or muscle tissue

The synergistic effects of ractopamine and porcine somatotropin on finisher gilt performance

Ractopamine hydrochloride (Paylean®, RAC, Elanco Animal Health Pty Ltd, Macquarie Park, NSW) is an approved ingredient for pigs used to increase lean tissue growth and improve production efficiency (Dunshea et al., 2005). Porcine somatotropin (Reporcin®, pST, OzBioPharm Pty Ltd, Knoxfield, VIC) is a protein naturally produced by the pig that induces the redirection of nutrients towards increased muscle growth and decreased fat growth (Dunshea et al., 2005). Recent research (Rikard-Bell et al., 2009) has shown that combining RAC and pST in the last two weeks of production improves feed efficiency. The aim of this experiment was to evaluate changes in production efficiency obtained by combining RAC and pST in the last four weeks of growth

Current recommended levels of dietary lysine in finisher pig diets are sufficient to maximise the response to ractopamine over 28 days but are insufficient in the first 7 days

Dietary ractopamine increases lean tissue deposition and responses increase as dose is increased provided sufficient dietary lysine is supplied. In Australia, diets supplemented with ractopamine (RAC) are formulated with 0.56 g available lysine per MJ digestible energy. The present study was conducted to investigate the interactions between dietary RAC and lysine on growth and carcass characteristics in ad libitum fed (13.8 MJ/kg) boars and gilts. The study involved 108 individually penned pigs at 17 weeks of age (64.1 +/- 0.57 kg) in a 2 by 2 by 3 factorial design, with the respective factors being sex (gilt or boar), dietary lysine (low and high, i.e. 0.56 or 0.65 g available lysine/MJ digestible energy, respectively) and dietary RAC (0, 5 or 20 mg/kg) for 28 days. Over the 28-day study duration, both lysine diets containing dietary RAC were sufficient to elicit a response in average daily gain (ADG) (+5.8%, P = 0.026) and carcass weight (3%, P = 0.045), but not in feed efficiency (FE) (P = 0.555). However, over the period of the first 7 days, there were interactions between the effects of RAC and lysine for FE (P = 0.025) and ADG (P = 0.023), with both traits being responsive only to dietary RAC containing the high lysine, which increased FE (+9.1%, P = 0.002) and ADG (+7.2%, P = 0.068). Dietary RAC improved FE in the latter stages of the study, namely Days 15-21 (+5.7%, P = 0.031) and Days 22-28 (+4.9%, P = 0.040). The high RAC diet reduced carcass P2 backfat (-16.5%, P < 0.001) and fat tissue deposition (-6.2%, P = 0.074) and high lysine tended to reduce fat tissue deposition (-13.3%, P = 0.072). A sex by lysine interaction (P = 0.043) was observed for lean tissue deposition at 28 days, such that only the high-lysine diet increased lean deposition in boars (+11%, P < 0.05) but not in gilts. Dietary RAC tended to increase lean deposition (+14.0%, P = 0.067) in the first 14 days; however, only the high RAC diet increased lean deposition (+9.6%, P < 0.05) over 28 days. In conclusion, the current recommended supplementation levels of lysine for commercial gilts and boars fed RAC may limit the response to dietary RAC if the feeding regime is for short durations and boars will not maximise their lean tissue deposition rates

Dietary ractopamine promotes growth, feed efficiency and carcass responses over a wide range of available lysine levels in finisher boars and gilts

The aim of this study was to investigate the performance and carcass responses of finisher boars and gilts offered a range of dietary lysine levels and three levels of dietary ractopamine hydrochloride (RAC). The study involved three experiments of 90 pigs each, totalling 270 individually penned pigs in a 2 by 5 by 3 factorial design comprising two sexes (gilts, boars), five levels of dietary lysine [0.40, 0.48, 0.56, 0.64, and 0.72 g available lysine per MJ of of digestible energy (DE), respectively] and three RAC dose regimes (0, 5 and 10 mg/kg) for 28 days. An outbreak of pneumonia (Actinobaccilus pleuropneumonia) at Day 26 in Experiment 1 compromised Day 28 data; however, Day 21 data was considered suitable across all three experiments. The results indicate that 0.56 g available lysine/MJ DE is sufficient to maximise average daily gain (ADG), feed conversion ratio (FCR) and carcass weight in gilts. Control boars indicated that ADG and FCR were not limited by the lysine : energy ratios fed in this study. Increasing levels of dietary lysine linearly increased ADG (P < 0.001), improved FCR (P < 0.001) and increased carcass weight (P = 0.001). Likewise, increasing dietary RAC further improved ADG(P = 0.001), FCR (P = 0.002) and carcass weight (P = 0.075) linearly. The critical lysine levels calculated for ADG and FCR in gilts fed diets supplemented with RAC were less than required for controls. Boars had higher critical lysine levels than gilts when supplemented with dietary RAC, and increasing dietary RAC increased critical lysine levels for ADG and FCR in gilts and boars. An interaction (P = 0.016) between dietary lysine and RAC occurred for FCR, such that the response to 5 mg/kg dietary RAC diminished in diets containing 0.64 g and 0.72 g available lysine/MJ DE; however, these diets elicited a response when supplemented with 10 mg/kg RAC. Responses in ADG, FCR and carcass weight to dietary RAC were noted when dietary lysine was at or below the current recommendations for RAC diets, and it was suggested that this may have been due to reduced efficiency of lysine utilisation due to chronic disease challenge. A Sex X RAC interaction (P = 0.027) occurred for carcass P2, indicating the higher RAC dose reduced carcass P2 in boars but not in gilts. When formulating finisher pig diets between 60 and 90 kg liveweight, consideration of the lysine : energy requirements for boars and gilts is needed in order to maximise ADG, FCR and carcass characteristics. When supplementing pigs with dietary RAC, a wide range of lysine : energy levels maybe employed; however, this is dependent on RAC inclusion level and probably herd health