Post-weaning and whole-of-life performance of pigs is determined by live weight at weaning and the complexity of the diet fed after weaning

The production performance and financial outcomes associated with weaner diet complexity for pigs of different weight classes at weaning were examined in this experiment. A total of 720 weaner pigs (360 entire males and 360 females) were selected at weaning (27 ± 3 d) and allocated to pens of 10 based on individual weaning weight (light weaning weight: pigs below 6.5 kg; medium weaning weight: 6.5 to 8 kg; heavy weaning weight: above 8.5 kg). Pens were then allocated in a 3 × 2 × 2 factorial arrangement of treatments with the respective factors being weaning weight (heavy, medium and light; H, M and L, respectively), weaner diet complexity (high complexity/cost, HC; low complexity/cost, LC), and gender (male and female). Common diets were fed to both treatment groups during the final 4 weeks of the weaner period (a period of 39 days). In the first 6 d after weaning, pigs offered the HC diets gained weight faster and used feed more efficiently than those offered the LC diets (P = 0.031). Pigs fed a HC diet after weaning tended to be heavier at the sale live weight of 123 d of age compared with pigs fed the LC diet (P = 0.056). There were no other main effects of the feeding program on growth performance through to slaughter. Weaning weight had a profound influence on lifetime growth performance and weight at 123 d of age, with H pigs at weaning increasing their weight advantage over the M and L pigs (101.3, 97.1, 89.6 kg respectively, P < 0.001). Cost-benefit analyses suggested there was a minimal benefit in terms of cost per unit live weight gain over lifetime when pigs were offered a HC feeding program to L, with a lower feed cost/kg gain. The results from this investigation confirm the impact of weaning weight on lifetime growth performance, and suggest that a HC feeding program should be focused on L weaner pigs (i.e., weaning weight less than 6.5 kg at 27 d of age) in order to maximise financial returns

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

Economic benefits of feeding high cost weaner diets are maximised when offered to pigs less than 6.5 kg at weaning

Growth performance is typically reduced in the period immediately post weaning while the piglet adapts to the new environment and feed source. This reduction in growth performance can negatively affect lifetime performance (Tokach et al., 1992). The use of high cost weaner diets during the first three weeks post-weaning is extensively practised to reduce the growth check and enhance performance to slaughter. It is hypothesized that the weight of the piglet at weaning will influence the growth performance and economic benefits from such a feeding program. Therefore, the aim of this study was to evaluate the benefits of feeding high cost weaner diets during the period immediately post weaning for pigs of different weaning weights

Yeast extract reduces histological indices of inflammation in the small intestine of weaned piglets

Feed additives are sometimes used in diets after weaning to modulate the structure and function of the gastrointestinal tract. Bio-Mos® (Alltech Biotechnology Pty Ltd), a mannan oligosaccharide derived from the cell wall of Saccharomyces cerevisiae, has been shown to influence positively the performance of weanling pigs (Miguel et al., 2004). However, the precise mechanism(s) for these effects has not been fully elucidated. This study tested whether Bio-Mos® included in diets for sows in gestation and lactation and then in a post-weaning diet would alter indices of inflammation in the small intestine of young pigs. This was presumed on the basis that Bio-Mos® has been suggested to influence pathogen colonization and/ or localized immunity (Davis et al., 2004)

Creep feed composition does not influence lifetime growth performance of pigs weaned at 22 or 29 days of age

Weaning of the piglet from the sow commonly results in a growth check immediately post weaning, while the piglet adapts to the new conditions and feed source. Offering solid creep feed during lactation aims to reduce this post weaning growth check. Several studies have outlined the benefits of creep feeding, however these benefits are not always observed and may not influence lifetime performance. Piglets weaned at an older age are likely to consume more creep feed than those weaned younger, therefore it is hypothesised that offering creep feed during lactation may have fewer benefits for early weaned animals. In addition, there is evidence to suggest an interaction between weaning age and the ingredient composition of the creep diet (Callesen et al., 2007). The aim of this experiment was to determine the impact of offering different creep diets during lactation on lifetime growth performance and carcase composition of pigs weaned at 22 or 29 d of age

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

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

Interactions between piglet weaning age and dietary creep feed composition on lifetime growth performance

The influences of creep feed composition and piglet weaning age on apparent creep feed disappearance and post-weaning performance were examined. A total of 24 gilts and 72 multiparous sows were selected at farrowing, and their litters allocated to a 2 by 2 factorial arrangement of treatments with the factors being weaning age (22 or 29 days of age) and the composition of the creep feed [simple (diet based predominately on cereals and animal and vegetable protein sources) or complex (diet based predominately on cereals, animal protein sources and 300 g/kg whey powder)]. Creep feed was offered to all litters from 9 days of age to weaning. While creep feed disappearance did not affect pre-weaning growth performance, there was a greater disappearance of the simple creep feed than the complex creep feed from 9 days of age to weaning (776 versus 461 g/litter, respectively, P ≤ 0.004). Apparent creep feed intake from individual piglets in a subset of litters was assessed at three time points (16 and 19 days of age and at weaning), allowing the characterisation of individual pigs as good, moderate, small or non-eaters. There was no difference between treatment groups (χ2 ≤ 6.27, P ≤ 0.71) in the characterisation of apparent creep feed disappearance by individual piglets, however piglets offered the simple creep diet before weaning consumed more feed (P ≤ 0.004) and gained weight faster (P ≤ 0.007) during the first 5 days after weaning than those animals offered the complex creep diet. Feed intake from weaning to 49 days of age also tended to be greater in pigs offered the simple creep diet before weaning (P ≤ 0.053), with this difference reflected in daily gain from weaning to 49 days of age (P ≤ 0.051). Despite these differences, creep feed composition did not influence lifetime growth performance or carcass composition. Pigs weaned at 22 days of age were heavier midway through the weaner period (49 days of age) than pigs weaned at 29 days of age (15.2 versus 14.3 kg, respectively, P ≤ 0.009), and tended to grow faster from birth to slaughter (616 versus 610 g/day, respectively, P ≤ 0.079). These data suggest that the provision of a complex creep diet during lactation may not improve lifetime growth performance above that of a less expensive creep diet. Weaning age may however influence lifetime performance, with weaning at 29 days of age tending to reduce rate of gain from birth to slaughter

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