Appropriateness of nutrient budgets for environmental risk assessment: a case study of outdoor pig production

Posted in: Pork Insight Articles, Welfare by admin on September 25, 2013 | No Comments

Outdoor pig production has expanded rapidly in recent years due to economic and market pressures. Recent research has shown that a high degree of heterogeneity in soil nutrient distribution can occur as a result of this agricultural system. This study examined the consequences of dietary manipulation on total excretion and spatial distribution of N and P in soils under outdoor sow production. Small areas of land chosen for excretion received excessive amounts of both N and P. Values equivalent to up to 2861 kg ha
1 of soluble N were observed in preferred areas, up to 90% of this was in organic forms. Within 15 months, applied nutrients were sufficient to saturate the soil profile in preferred areas with respect to P and produce areas that represented a significant environmental risk. Lowering the amount of N and P in the diet has potential to reduce environmental impact but cannot eliminate spatial variability. The use of simple input output nutrient budgeting approaches may underestimate losses of N and P as they cannot account for mineralisation rates of organic nutrients excreted or for P saturation in areas preferentially used for excretion.

Animal welfare and economic optimisation of farrowing systems

Posted in: Pork Insight Articles, Welfare by admin on | No Comments

In many countries, including the UK, the majority of domestic sows are housed in farrowing crates during the farrowing and lactation periods. Such systems raise welfare problems due to the close confinement of the sow. Despite the fact that many alternative housing systems have been developed, no commercially viable/feasible option has emerged for large scale units. Current scientific and practical knowledge of farrowing systems were reviewed in this study to identify alternative systems, their welfare and production potential.

Sandra Edwards

Development of a spreadsheet based financial model for pig producers considering high welfare farrowing systems

Posted in: Pork Insight Articles, Welfare by admin on | No Comments

The model was developed to address the recognized deficiency in financial information on free-farrowing systems, and assist pig producers in estimating the cost of producing pigs in such systems.  The model is available on line at  http://www.ncl.ac.uk/afrd/research/project/4378.   Users can select from eight  different types of farrowing accommodation and four gestation housing systems, with additional variations on floor type and feeding system.  Input data on herd size and productivity are entered into one active sheet and, using built-in data on housing and other input costs, the model computes the cost of producing a weaner pig 8kg at 4 weeks of age) in each gestation/farrowing system combination selected.  Sensitivities to input or output changes can also be evaluated by altering herd performance.  The use of this model provides pig producers, policy makers and other stakeholders with a means to estimate  the likely cost of pig production prior to any investment in a new housing system.

Sandra Edwards

The welfare implications of large litter size in the domestic pig I: biological factors

Posted in: Pork Insight Articles, Welfare by admin on | No Comments

Increasing litter size has long been a goal of pig breeders and producers, and may have implications for pig welfare. This paper reviews the scientific evidence on biological factors affecting sow and piglet welfare in relation to large litter size.  It is concluded that, in a number of ways, large litter size is a risk factor for decreased animal welfare in pig production. Increased litter size is associated with increased piglet mortality, which is likely to be associated with significant negative animal welfare impacts.  In surviving piglets, many of the causes of mortality can also occur in non-lethal forms that cause suffering. Intense teat competition may increase the likelihood that some piglets do not gain adequate access to milk, causing starvation in the short term and possibly long-term detriments to health. Also, increased litter size leads to more piglets with low birth weight which is associated with a variety of negative long-term effects. Finally, increased production pressure placed on sows bearing large litters may produce health and welfare concerns for the sow. However, possible biological approaches to mitigating health and welfare issues associated with large litters are being implemented. An important mitigation strategy is genetic selection encompassing traits that promote piglet survival, vitality and growth. Sow nutrition and the minimisation of stress during gestation could also contribute to improving outcomes in terms of piglet welfare. Awareness of the possible negative welfare consequences of large litter size in pigs should lead to further active measures being taken to mitigate the mentioned effects.

Sandra Edwards

Effect of dietary fibre on the behaviour and health of the restricted fed sow

Posted in: Pork Insight Articles, Welfare by admin on | No Comments

The usual restricted feeding level during gestation, whilst adequate to maximise economic performance, might not fulfil behavioural needs of the sow. Hunger and frustration of feeding motivation have been linked to the occurrence of stereotypic activity, and accentuate aggression and feeding competition in group-housing systems. Incorporation of fbre in diets to increase bulk, without changing the daily dietary energy supply, has been shown to result in at least a doubling of eating time, a 20% reduction in feeding rate, a 30% reduction in operant response in feed motivation tests, a reduction of 7-50% in stereotypic behaviour, and a decrease in general restlessness and aggression. Results suggest a reduced feeding motivation, but only if nutrient intake with fibrous diets meets the nutrient requirements of the animals. Investigations of circulating glucose, insulin and volatile fatty acid levels in sows fed fibrous diets indicate a more constant nutrient absorption and greater microbial fermentation in the gut, which should increase satiety. There is inadequate information on effects of dietary fibre on physiological stress and health. In addition to welfare considerations, a range of technical requirements and economic factors must be considered when making decisions on the use of dietary fibre during gestation.

Sandra Edwards

Effects of Feed Station Design on the Behaviour of Group-Housed Sows Using an Electronic Individual Feeding System

Posted in: Pork Insight Articles, Welfare by admin on | No Comments

With electronic feeding system, sows carry an electronic identification device on a collar or ear tag and feed sequentially at a computer-controlled feed-dispensing station. The design of this station is important in maximising the number of sows which can share it, whilst minimising aggression. Earlier studies carried out with a “double-entry” feed station design, which allowed two separately housed groups of sows to share the same feed dispensing system, indicated a capacity of up to 50 sows (Edwards et al., 1984a). However, studies of this and other rear exit designs showed that, early in the feed cycle, a number of sows congregated behind the feed station and hindered the sow backing out (Edwards et al., 1984b; Smith et al., 1986). Although this did not cause major problems with aggression, it appeared that a forward exit system might improve station use. The following studies were, therefore, undertaken to investigate the effects of different feed station designs on the behaviour of sows using the station.

Sandra Edwards

Perinatal mortality in the pig: environmental or physiological solutions?

Posted in: Pork Insight Articles, Welfare by admin on | No Comments

The evolutionary strategy adopted by the pig is to produce a large number of relatively undeveloped offspring. Such a strategy demands that relatively little investment is made in each individual piglet pre-natally, and that piglets which are surplus to resources should die at an early stage with least prejudice to their littermates. Thus, inherent variation in neonatal competitiveness is an advantage and survival of the strongest is promoted. Genetic selection strategies resulting in increased litter size and reduced physiological maturity at birth have compounded these effects, making piglet mortality an intractable problem. Records of piglet mortality in commercial units indicate that most deaths of liveborn piglets are attributed to crushing and starvation, but these ultimate causes are often secondary to the effects of perinatal hypothermia. Piglet survival is the outcome of complex interactions between the sow, the piglet and the environment. Commercial strategy has focused on improving the farrowing environment to modify sow behaviour and increase human intervention. However, concerns about the welfare implications of confining sows in farrowing crates may limit the use of such approaches in the future and change the focus towards genetic selection for characteristics in both the dam and offspring which promote survival. Methods of improving the inherent viability of the piglet, for example by increasing birth weight, neonatal vigour and thermoregulatory ability, have been commercially less effective to date, with intra-partum hypoxia exerting an overwhelming influence. A better understanding of neonatal and maternal physiology in relation to placental transfer of nutrients, regulation of the parturition process, colostrum transfer and expression of appropriate maternal behaviour is required for the development of effective future solutions.

Sandra Edwards

Identification of risk factors associated with poor lifetime growth performance in pigs

Posted in: Pork Insight Articles, Welfare by admin on | No Comments

During the production period from birth to slaughter there are some pigs that grow markedly slower, despite conditions that seem to support the growth of their contemporaries. This reduction in growth inevitably leads to weight variation within a group, causes difficulties with management, and results in system inefficiencies. By understanding the factors that contribute to poor growth, the performance of these slow growing pigs might be improved, thereby decreasing the overall variability at slaughter. The aim of this paper was to analyze the factors associated with poor growth performance in pigs from birth to slaughter, determine the effect of piglet birth weight (BiW) and weaning weight (WW) on lifetime growth, and investigate the capacity of small piglets to compensate for any BW deficit. Two industry databases, with individual data for approximately 40,000 and 90,000 pigs, respectively, and containing BW profiles and relevant variables, were analyzed. Body weight at birth, weaning, intermediate, and finishing stages were available as well as sex, month of birth, litter size information (number born alive and total born including still born), sow parity number, and length of gestation. Absolute and relative growth rates, based on adjusted BW for age, were calculated for each time interval and 3 types of analysis were performed: a logistic regression, a continuous linear plateau model, and a weight category analysis. For both datasets poor absolute and relative growth from birth to final BW was associated with low BiW (P < 0.001), low WW (P < 0.001), sex (P < 0.001), breed code (P < 0.001), and month of birth (P < 0.001). The linear plateau model suggested that the relationship between BiW and lifetime growth was not linear beyond 1.91 (database 1) or 1.84 (database 2) kg; the same applied to the relationship between WW at 21 d and final BW (FW) growth, which was not linear beyond 7.53 kg. Finally, the weight category analysis revealed that piglets with the lightest BiW were able to exhibit compensatory growth from BiW to FW with 74 (database 1) and 82% (database 2) moving at least 1 BW category. It is concluded that growth performance to slaughter is not solely reliant on pig BiW, with WW also playing a critical role. Additionally, piglets with BiW below the average are capable of some degree of compensatory growth; this provides the opportunity for managing them so as to improve their lifetime growth.

Sandra Edwards

Social rank and feeding behaviour of group-housed sows fed competitively or ad libitum

Posted in: Pork Insight Articles, Welfare by admin on | No Comments

Animals living in a group generally establish a dominance hierarchy which enables the group to function without the necessity of fights whenever group members encounter each other (Beilharz and Cox, 1967). A stable dominance hierarchy can be maintained by subtle signals and give high-ranking animals priority of access to resources in limited availability (Banks et al., 1979). In intensive housing systems this can have serious consequences for low-ranking animals (Csermely and Wood-Gush, 1990), owing to close proximity of high-ranking sows and, in some cases, limitation of resources.

A restricted feeding regimen is adopted in commercial practice to maintain an almost constant body-condition of the sow throughout the reproductive cycle. Depending on the manner of distribution of this limited amount of food between sows in a group-housing situation, competition can result in unequal distribution of food and loss of condition of low-ranking sows (Brouns and Edwards, 1992 ). This kind of competition is likely to occur in feeding systems where the food is distributed once or twice daily on the floor (floor-feeding) and is aggravated by a low feeding level (McBride et al., 1964; Baxter, 1983 ). A  conventional diet is concentrated in nutrients and although it is sufficient for good health and performance, it might not fulfil other needs of the sow, since the small amount of food is unlikely to give a feeling of satiety (Lawrence et al., 1988 ). Provision of
a diet ad libitum should, in theory, obviate the need for competition and eliminate negative consequences for low-ranking sows.
In this experiment, the consequences of food available, in limited quantities once daily or ad libitum, on live weight gain and feeding behaviour of sows of different social rank in a group-housing situation, were investigated.

Sandra Edwards

The welfare implications of large litter size in the domestic pig II: management factors

Posted in: Pork Insight Articles, Welfare by admin on | No Comments

Increasing litter size has long been a goal of pig breeders and producers in many countries. Whilst this has economic and environmental benefits for the pig industry, there are also implications for pig welfare. Certain management interventions
are used when litter size routinely exceeds the ability of individual sows to successfully rear all the piglets (ie viable piglets
outnumber functional teats). Such interventions include: tooth reduction; split suckling; cross-fostering; use of nurse sow systems and early weaning, including split weaning; and use of artificial rearing systems. These practices raise welfare questions for both the piglets and sow and are described and discussed in this review. In addition, possible management approaches which might mitigate health and welfare issues associated with large litters are identified. These include early intervention to provide increased care for vulnerable neonates and improvements to farrowing accommodation to mitigate negative effects, particularly for nurse sows. An important concept is that management at all stages of the reproductive cycle, not simply in the farrowing accommodation, can impact on piglet outcomes. For example, poor stockhandling at earlier stages of the reproductive cycle can create fearful animals with increased likelihood of showing poor maternal behaviour. Benefits of good sow and litter management, including positive human-animal relationships, are discussed. Such practices apply to all production situations, not just those involving large litters. However, given that interventions for large litters involve increased handling of piglets and increased interaction with sows, there are likely to be even greater benefits for management of hyper-prolific herds.

Sandra Edwards