Invited review: Aspects of gastrointestinal tract growth and maturation in the pre- and postweaning period of pigs

The growth and development of the gastrointestinal tract (GIT) of the young pig, both before and after parturition, is critical for the ani-mal’s future growth and development, efficiency of feed conversion to body depots, and, ultimately, its survival. The perinatal development of the GIT encompasses a prenatal phase, a neonatal phase, and the postweaning phase, which is associated with the adaptation of the GIT to utilize solid feed after the piglet is weaned. The consumption of colostrum, initially, and then milk after birth provides nutrients and compounds for piglets that are critically important as stimuli and substrates to the GIT that in turn evoke a suite of anatomical, immunological, biochemical, physiological, and regulatory processes that advance the overall maturity of the GIT. However, at weaning the combined influence of the various stressors imposed causes a hiatus in the growth and development of the GIT, such that the newly weaned pig endures a “growth check” while exposing it to a greater disease and health risk. Low and variable feed intake is a major outcome of the weaning process, but nevertheless, there are numerous nutritional/manage-ment interventions producers can implement in an attempt to overcome this major issue. This review summarizes some major aspects of, and influences on, GIT growth, development, and maturation in the pre- and postweaning period of pigs, demonstrating that postnatal influences occur in utero and that evolution of the GIT continues to occur after weaning

Performance and intestinal responses to dehulling and inclusion level of Australian sweet lupins (Lupinus angustifolius L.) in diets for weaner pigs

A total of 180 entire male weaner pigs weighing 6.4 ± 0.1. kg (mean ± SEM) and housed in pairs was used in a completely randomised block design with 9 dietary treatments (n= 10 pens). Pigs were blocked based on weaning weight. The diets were (i) a wheat-based control diet containing 240. g/kg of milk products (whey and skim milk powder), and (ii) 8 diets containing whole or dehulled lupins (cv. Coromup) that substituted the milk products at 60, 120, 180 and 240. g/kg of diet (replace 25%, 50%, 75%, or 100% of the milk products in the control diets). The diets were isoenergetic [15. MJ digestible energy (DE)/kg], and were formulated to contain the same ileal standardised digestible lysine content (0.85. g/MJ DE) and ideal patterns of other essential amino acids. Pigs receiving 240. g/kg of dehulled lupins grew slower (P<0.05) than pigs fed the other diets mainly due to decreased feed intake. Pigs fed diets containing more than 180. g/kg of dehulled lupins had a higher faecal β-haemolytic Escherichia coli score on day 3 after weaning (P<0.05). Moreover, inclusion of 240. g/kg of whole lupin or more than 180. g/kg of dehulled lupins increased (P<0.001) plasma urea nitrogen (PUN) levels. Total tract apparent digestibility (TTAD) of dry matter decreased (P<0.001) in all lupin diets compared with the control diet. These data indicate that inclusion of dehulled lupin immediately after weaning should be limited to less than 180. g/kg whilst whole lupins can be included up to 240. g/kg without deleterious effects on production and intestinal health

Effect of variety, growing region and growing season on digestible energy content of wheats grown in Western Australia for weaner pigs

An experiment was conducted to examine the digestible energy (DE) content for weanling pigs in a cohort of wheats grown in Western Australia, and to establish relationships between DE content and their chemical composition. The 3 5 3 5 2 factorial experiment examined the wheat variety (Arrino, Stiletto and Westonia), growing location (high, medium and low rainfall zone) and harvest year (1999 and 2000). Pigs (no. = 5 per diet) aged about 28 days were given a diet at a level of 0.05 5 live weight containing 900 g/kg of the wheat and an acid-insoluble ash marker for 10 days, with samples of faeces collected from each pig for the final 5 days. The average live weight of pigs was 6.6 (s.d. 0.77) kg. The DE content of wheats harvested in 1999 varied by up to 1.3 MJ/kg, while wheats harvested in 2000 varied by up to 1.8 MJ/kg. When the 2 years' data were combined, the DE content ranged from 12.5 to 14.4 MJ/kg. Both the variety and growing region significantly influenced (P 0.05) with the wheats harvested in 2000. In addition, the precipitation level (mm) during the growing season of wheats was strongly correlated (r = -0.821, P < 0.01) to the DE content of wheat in year 1999, but was not correlated in 2000. The results indicate that the genetic and environmental conditions during the growth of wheat have a significant impact on the utilization of plant energy in weaner pigs, and that greater attention needs to be paid to these influences in the assignment of energy values for wheats given to weaner pigs

Efficacy of a reduced protein diet on clinical expression of post-weaning diarrhoea and life-time performance after experimental challenge with an enterotoxigenic strain of Escherichia coli

Previous experiments have shown that feeding a reduced protein diet within the first 2 weeks post-weaning reduces gastrointestinal protein fermentation and clinical expression of post-weaning diarrhoea (PWD). However, growth of young pigs receiving a reduced protein diet without crystalline essential amino acids (CEAA) supplementation is depressed after weaning. It has been argued that the short-term performance reduction caused by feeding a reduced protein diet would be compensated and the lifetime performance of pigs would not be affected. An experiment was therefore conducted to examine PWD and lifetime growth of pigs after feeding a reduced protein diet without and with CEAA supplementation for 2 weeks after weaning. Two hundred individually housed pigs weaned at 21 d of age (Large White×Landrace, castrate:female ratio of 1:1, mean±SEM body weight of 5.5±0.05kg) were stratified to one of four dietary treatments (n=50): High protein+antimicrobial compound diet (HP+AMC, 230g crude protein (CP) with 2.5g lincospectin and 3g zinc oxide per kg feed), High protein diet (HP, 230gCP/kg), Reduced protein+amino acid supplemented diet (RP+AA, 185gCP/kg with added CEAA up to HP level), and Reduced protein diet (RP, 185g CP/kg without CEAA supplementation). Pigs were fed the experimental diet for 2 weeks and then all pigs were fed the same series of commercial diets until slaughter. All pigs were experimentally infected with an enterotoxigenic strain of E. coli (6 and 10mL of 1.9×109cfu/mL, serotype O149:K91:K88) at 72, and 96h after weaning. Infection increased plasma haptoglobin levels (P0.05). Carcass characteristics were not affected (P>0.05) by the treatments. The results indicate that although feeding a RP diet without CEAA supplementation decreased performance after weaning, it did not influence lifetime performance or carcass characteristics and reduced the clinical expression of PWD

Opportunities and strategies to reduce effluent production by pigs

There is increasing concern about the impact that agriculture is having on the environment. As far as the pig industry is concerned, a significant proportion of nutrients that are fed to pigs end up in the effluent. There are two basic options for reducing the amount of effluent produced by pigs. The first is to reduce the oversupply of nutrients being fed, and the second is to improve the efficiency with which nutrients are utilized by the animal. In this paper some of the strategies that currently exist for reducing the output of N and P in piggery waste are discussed. Particular emphasis is given to the use of computer modelling techniques to calculate the nutrient requirement of pigs at various stages of growth, and feeding strategies that make greater use of synthetic amino acids and enzymes

Are observer ratings influenced by prescription? A comparison of Free Choice Profiling and Fixed List methods of Qualitative Behavioural Assessment

Qualitative methods of behavioural assessment use observer rating scales to score the overall demeanour or body language of animals. Establishing the reliability of such holistic approaches requires test and validation of the methods used. Here, we compare two methodologies used in Qualitative Behavioural Assessment (QBA): Fixed-Lists (FL) and Free-Choice Profiling (FCP). A laboratory class of 27 students was separated into two groups of 17 and 10 students (FL and FCP respectively). The FL group were given a list of 20 descriptive terms (used by the European Union's Welfare Quality ® program), shown videos of group-housed sows, and as a group discussed how they would apply the descriptive terms in an assessment. The FCP group were shown the same footage but individually generated their own descriptive terms to describe body language of the animals. Both groups were then shown 18 video clips of group-housed sows and scored each clip using a visual analogue scale (VAS) system. We analysed the VAS scores using Generalised Procrustes Analysis (GPA) for each observer group separately, which indicated high inter-observer reliability for both groups (FL: 71.1% of scoring variation explained, and FCP: 63.5%). There were significant correlations between FL and FCP scores (GPA dimension 1: r 16 =0.946, P 0.7 is usually accepted to show strong agreement). This study demonstrates that, regardless of whether they are given their terms or are allowed to generate their own, observers score sow body language in a similar way. Strengths and weaknesses within the two methods were identified, which highlight the importance of providing thorough and consistent training of observers, including providing good quality training footage so that the full repertoire of demeanours can be identifie

Evaluation of sugarcane-derived polyphenols on the pre-weaning and post-weaning growth of gilt progeny

Gilt progeny (GP) exhibit poorer growth compared with sow progeny (SP), particularly in the pre-weaning and post-weaning period. Late gestation/lactation sow diets and weaner diets were supplemented with 0.5% Polygain (POL), a sugarcane extract rich in polyphenols, to collectively improve GP growth in these periods. Gilts (n = 60) and sows (n = 68, parities 2 and 3) were fed a control or POL diet. Weaned GP (n = 79) and SP (n = 92) born to these dams were also fed either a CON or POL diet. Gilts litters weighed less than sow litters at birth and 21 days (p < 0.001 for both) and were not improved by POL (p = 0.80 and 0.54, respectively). GP were lighter than SP at day 7 and day 14 post-weaning (p < 0.001 for both) and were not improved by the POL diet at these timepoints (p = 0.61 and 0.97, respectively). Plasma interleukin-1β (IL-1β) was increased at weaning despite POL supplementation (p = 0.022) and GP had reduced IL-1β overall (p = 0.021). Overall, POL was unable to improve growth in GP and the attenuated immune response seen in GP could be contributing to their poor growth performance

Clean, green and ethical pig production in Australia

The concept of ‘clean, green and ethical’ pig production is attracting growing attention around the world as producers, international traders of pig, and consumers are becoming increasingly aware of sustainable and socially acceptable animal production systems. While the terminology 'clean, green and ethical' does not lend itself readily to an all-encompassing definition, in pig production it broadly refers to a rearing system with scientifically sound and ethical practices that underpins the production of safe and wholesome pork. Both the physical environment and management of the environment, for example controlling nitrogen and phosphorus emissions, are relevant to ‘clean, green and ethical’ pig production. Outdoor housing systems used in Australia based on litter (straw, rice hulls) portray a more natural image of pig production than conventional indoor housing systems based on steel and concrete, even though many of the same practices (e.g. antibiotic injections) and problems (e.g. enteric diseases) occur in both systems. Animal welfare is also an important and often contentious issue for pig production; evidence of this includes the recent spate of announcements by large vertical integrators in the USA and Canada of plans to phase out sow stalls following intense pressure from animal rights lobbyists. Other factors to be considered in ‘clean, green and ethical’ pig production include Quality Assurance (QA), the ability to trace individual pigs to their property of origin, aspects of pig genetics, the use of feedstuffs free of genetic modification, no hormonal or antibiotic residues in pig meat, and specific-pathogen free herds. Issues associated with antibiotic use are integral to the basic premises of ‘clean, green and ethical’ pig production. Restrictions or outright bans on the use of antibiotic feed additives, as occurred in the European Union from January 1st 2006, reinforce the notion that antibiotics denigrate the notion of ‘clean, green and ethical’ production even though pig welfare is likely improved by their use. This paper reviews the practical approach that Australia has taken to the production of pigs and pig meat that will meet the discerning needs and demands of our current and future domestic and international markets. We have also used some international data and commentary to highlight certain aspects of our discussions

Improving welfare and production in the peri-weaning period: Effects of co-mingling and intermittent suckling on the stress response, performance, behaviour, and gastrointestinal tract carbohydrate absorption in young pigs

We investigated the effect of different pre-weaning interventions on performance, aspects of behaviour, and selected neuroendocrine, inflammatory and immune indices in 593 weanling pigs (59 litters, weaning age 22 ± 1.7). Measurements were taken at various time points two weeks before and after weaning. Sugar absorption tests (20% mannitol and 20% galactose solutions) were used to assess gastrointestinal tract (GIT) absorptive capacity. One week before weaning, litters were either co-mingled (CoM) for 8 h daily with another litter or not co-mingled (NoCoM). Half of the litters were also subjected to intermittent suckling (IS) involving separation from their sow for 8 h daily and the other half remained with their sow (NoIS). Hence, four treatments were produced in a 2×2 factorial design; (1) CoM IS (n = 16 litters), (2) CoM NoIS (n = 14 litters), (3) NoCoM IS (n = 16 litters), (4) NoCoM NoIS (n = 13 litters). Measurements are compared within each of the main effects (CoM or IS) unless otherwise stated. Acute weaning stress was evidenced by increases in cortisol, haptoglobin and N: L ratios when data were combined (P < 0.001). However, there were tendencies (P < 0.1) for lower cortisol in IS pigs and higher N: L ratios in CoM pigs at weaning. While CoM did not affect performance before weaning, growth (P < 0.05), feed intake (P < 0.05) and body weight (P < 0.05) were reduced in CoM pigs 7-14 days after weaning. One week of IS before weaning improved feed intake before weaning (P < 0.01), resulting in better growth (P = 0.01) and a tendency (P < 0.1) for a higher feed intake 2-7 days after weaning. Co-mingled piglets had more scratches 4 days before weaning (P < 0.001), but tended to have fewer scratches 2 days after weaning (P < 0.1). Pigs exposed to either IS or CoM displayed more sleeping behaviour the day after weaning (P < 0.01 and P < 0.001). A higher mannitol absorption was evident in CoM NoIS pigs 3 days after weaning (P < 0.01), and galactose absorption was reduced in IS pigs 3 days before weaning (P < 0.05) and tended to be reduced 3 days after weaning (P < 0.1), likely reflecting a GIT adaptive response. Overall, despite improvements in mannitol absorption and behaviour, there was no beneficial effect of CoM on performance after weaning. Alternatively, IS improved behaviour and performance during the first week after weaning