Housed pigs are exposed chronically to aerial pollutants, principally dust and ammonia, at concentrations that may affect performance, possibly by raising the incidence and prevalence of multi-factorial respiratory diseases. Tolerable limits for aerial pollutants are unknown. The aim of this experiment was to test the hypothesis that chronic exposure of weaner pigs to controlled concentrations of aerial dust and ammonia lead to slower growth and lower feed intake compared with controls kept in ‘fresh air’.

Visual imaging systems provide daily plan (overhead) measurements of pigs. These allow monitoring and control of pig growth, as is essential to production efficiency. Schofield et al., 1999 suggest that size measurements can provide accurate estimates of live weight, but a description of growth in terms of size and shape may also give a direct quantification of body form and value. This report presents analyses of the growth of pigs of two commercial breed types in terms of live weight, body plan area and ham width, and examines the relationship between observed body shapes of living pigs and their dissected body composition.

There is much interest in the manipulation of the fatty acid composition of milk fat so as to improve its health characteristics in the human diet. In an earlier study there was an indication that the concentration of fatty acids in milk may change with time when feeding whole oilseeds rich in polyunsaturated fatty acids (PUFA). In particular a tendency for an increase in CLA and C18:1 and a reduction in C18:2 and C18:3 concentrations with time were seen. The present study was therefore undertaken to examine the changes in the fatty acid composition of milk from high yielding dairy cows fed diets rich in monounsaturated fatty acids (MUFA) or PUFA over an extended period.

Current medical advice is to reduce consumption of saturated fat, in favour of polyunsaturated fat, and to increase the consumption of ω-3 polyunsaturated fatty acids (PUFAs) at the expense of ω-6 PUFAs. Fat of ruminant origin, although it has a nutritionally favourable ω-6: ω-3 ratio, is rich in saturated fatty acids (SFAs), which have been linked to incidence of coronary heart disease in humans. However, when compared to non-ruminant fat, fat of ruminant origin has a high concentration of conjugated linoleic acid (CLA), which is considered to have anticarcinogenic properties (Belury, 1995). Grass finishing of cattle increased the concentration of CLA and the PUFA:SFA ratio (P:S) when compared with concentrate-based finishing (French et al., 2000). The objective of this study was to investigate the relationship between duration of grass-finishing of cattle and the fatty acid profile of intramuscular lipid.

Studies undertaken to evaluate long responses to concentrate feeding, normally assess the direct effects (i.e. the effects during the period of increased feeding). However in addition to the direct responses to concentrate feeding during the experimental period, it has been recognised that additional nutrients fed during one stage of lactation may result in improvements in animal performance in later lactation or in the subsequent lactation. Keady et al. (2002) reported that the milk yield response to concentrate proportion in the diet differed between Holstein (HF) and Norwegian (NC) dairy cattle with responses of 1.4 and 0.8 kg corrected milk/kg concentrate dry matter (DM) respectively. The objective of the present study was to evaluate the effects of concentrate proportion in the diet in the previous lactation on animal performance in the subsequent lactation. The effect of concentrate proportion in the diet on animal performance of HF and NC dairy cattle was also evaluated.

Labour constitutes a major and increasing cost on dairy farms, while at the same time, the availability of skilled labour is decreasing. In addition, younger farmers are placing an increasing emphasis on lifestyle. Consequently, there is an increased interest in milk production systems involving reduced labour inputs. In view of the fact that approximately 33% (O’Brien et al., 2002) of the daily labour input on dairy farms is associated with the milking routine (herding, milking and washing), the adoption of once daily milking would appear to offer considerable potential to reduce labour inputs. This study examined the effect of once-daily milking, in late lactation, on animal performance.

During the transition period (defined as three weeks prior to calving to three weeks post-calving) heifers are exposed to physiological, nutritional, management, and social changes as they enter the dairy herd. One obvious change is the introduction of heifers to the milking parlour. Previous work has shown that when mature cows were milked in unfamiliar surroundings, milk yield, milk flow rate and milking duration were affected due to increased stress (Rushens, et al. 2001). The objective of the current study was to investigate the effects of habituating heifers to the milking parlour pre-calving on the subsequent performance of Holstein-Friesian and Norwegian dairy herd replacements.

As NZ milk production is predominantly seasonal and reliant on pasture growth, a high pregnancy rate within a short time after planned start of mating is essential to match feed supply to production. A Holstein-Friesian strain trial was established in Hamilton, New Zealand, to investigate the physical and financial performance of three strains of dairy cattle under a range of pasture based systems that differ in stocking rate and supplementary feeding. The three strains of cows were: Overseas High genetic merit (OS), New Zealand High genetic merit (NZH) and New Zealand Low genetic merit (NZL). The objective of this study was to predict reproductive performance from information available prior to mating, as an aid to on-farm decisions.

In pasture-based dairying systems it is important to maintain a 365-day calving interval, which requires that cows have a rapid resumption of postpartum ovulatory activity and high conception rates. The major form of infertility in New Zealand (NZ) dairy cows is an extended postpartum anovulatory interval (ppai; Macmillan, 2002), a problem that can be exacerbated by low body condition score (BCS) at calving (McDougall, 1995). Furthermore, Holstein cows, originating from North American genetic strains (Overseas; OS), which have been widely used in NZ in recent years, have longer intervals to first mating and conceive later than do NZ strains, suggesting a possible delay in the initiation of postpartum cyclicity (Harris and Winkleman, 2000). Worldwide, there is concern over an apparent decline in the fertility of Holstein-Friesian dairy cattle (Butler et al., 1995; Royal et al., 2000). The purpose of this trial was to determine whether there was a difference in ppai and BCS between NZ and OS Holstein Friesians that may affect reproductive performance.

Nematodes are a particular challenge to animal health and productivity in organic sheep systems, where the prophyllactic use of anthelmintic is prohibited. The peri-parturient rise in faecal egg output, a consequence of relaxation of host immunity in late pregnancy and early lactation, is potentially a key factor in the epidemiology of parasitic gastro-enteritis on organic sheep farms. Coop and Kyriazakis (1999) developed a hypothesis to explain the relationship between nutrition and periparturient breakdown of immunity to parasites, and there is now an increasing body of evidence for the involvement of dietary protein (Houdijk et al 2001). The objective of this study was to test this hypothesis in organically managed ewes carrying a mixed, naturally acquired infection, grazing on grass/clover in early lactation, and to examine the potential for a nutritional approach to parasite control in commercial practice.

There is an increasing body of evidence to support the view that the periparturient breakdown of immunity to parasites has a nutritional basis; an increased supply of metabolizable protein (MP), at times of MP scarcity, would reduce gastrointestinal nematode egg excretion and worm burdens in periparturient ewes (Houdijk et al., 2001). However, the rate at which MP supply can improve expression of immunity to gastrointestinal nematodes is not known. The objective of this experiment is to assess this rate, which will be studied through reducing the degree of MP scarcity.

With increasing incidence in anthelmintic drench resistance, it is appropriate that more sustainable approaches to controlling nematode infections in livestock should be investigated. It is believed that larval contamination of pasture originates from the mature breeding ewe during the periparturient breakdown of immunity. Donaldson et al. (1998) reported that increasing the metabolisable protein (MP) supply of the ewe in late pregnancy may moderate the periparturient relaxation of immunity. The most pronounced results to date are those involving the supplementation of diets with fishmeal, believed to be related to the ‘protected’ protein content of the ration. Fishmeal increases both MP and polyunsaturated fatty acid content of the diet but as yet it is unclear which of these components of the diet may affect immunity to parasites. This study investigated the role of MP supply in maintaining immunity to parasitic infection in pedigree Friesland dairy ewes.

The exposure of pigs to different pathogens compromises productivity, i.e. reduces weight gain and food intake (Balaji et al., 2000; Greiner et al., 2000), even in the absence of clinical disease. Infection also often causes the release of acute phase proteins and the proliferation of certain leucocyte subsets (Baumann and Gauldie, 1994; Licence and Binns, 1995). Therefore, it may be hypothesised that associations should exist between productivity and a range of immunological traits in apparently-healthy animals facing the same infectious challenge. This would be important in pigs suffering sub-clinical infections, as it would enable predictions of health status and effects of infection on performance. This study investigated such associations in apparently-healthy pigs facing unknown subclinical challenges.

The start of the lactation period is related to an increase in the number and severity of claw horn lesions on dairy cows and heifers (Offer et al., 2000). Heifers have important physiological differences, presenting a different pattern of lesion formation when compared to cows (Offer et al., 2000). The rearing of heifers, their growth rate, feeding and the occurrence of foot problems have an influence over the health of their feet when the animals get older (Thomas et a., 1999). The objective of this experiment was to study the pattern of lesion formation of the sole horn in the pre- and postpartum period of first calving heifers and to compare it to mechanical tests.

Mixing piglets pre-weaning at 14 days of age has been shown to improve post-weaning performance and reduce skin lesions caused by fighting without any detrimental affects on pre-weaning performance and behaviour (Allen et al., 2000). The stress associated with weaning has been shown to alter immune function of piglets and increase their susceptibility to infections. The aim of this experiment was to assess the effect of mixing piglets pre-weaning on their humoral and cell-mediated immune responses post-weaning.

Evidence suggests that pigs prefer to associate with their mother and littermates over other group members (e.g. Newberry & Wood-Gush, 1986) and with pigs introduced with them into an established group over resident pigs (Durrell et al., 2000). Few studies, however, have examined whether long-term preferential associations or ‘friendships’ are formed between pairs of pigs within a group. Those studies that have been carried out have either involved observations carried out over extremely limited time periods (e.g. Stookey & Gonyou, 1998) or have simply identified pairs that spend the most time together instead of examining statistically whether some pairs associate significantly more than others (Newberry & Wood-Gush, 1986). The aim of this investigation was to determine whether pairs of pigs form preferential associations, based on statistical analyses of long-term lying partner preferences.

Adult pigs maintained outdoors spend a very high proportion of their time chewing stones. The activity is persistent, taking up 30-50% of the 6 h after feeding, and highly repetitive in its pattern of component activities; it is reminiscent of the stereotypies (bar-biting, vacuum chewing, rooting at floors and foot-scraping) in stall- and cubicle-housed sows indoors. Consistent with this hypothetical parallel, the amount of stonechewing in outdoor sows in different environments increased systematically with impoverishment in the habitat (Horrell and A’Ness, 1999). Two factors that influence the incidence of oral stereotypies are feed restriction (Appleby and Lawrence, 1987) and a past history of stereotypical behaviour (Lawrence et al., 1991). This project aimed to determine whether these factors have an impact on the incidence of stonechewing.

Nose rings have been proven to reduce the occurrence of paddock rooting behaviour, however, the practice has been questioned on ethical grounds. The aim of this experiment was to identify a suitable alternative. Previous attempts to reduce paddock damage by dietary means have succeeded in redirecting rooting behaviour (Bornett et al., 2002) or at reducing the overall frequency of paddock rooting behaviour (Braund et al., 1998) but neither succeeded in reducing paddock damage. It is hypothesised that whilst the experiment of Bornett et al. (2002) fulfilled the sow’s desire to forage, and the experiment of Braund et al. (1998) fulfilled the sow’s need to feel satiated; neither fulfilled both criteria simultaneously. In this experiment, both of these needs were considered and it was therefore hypothesised that paddock damage would be reduced.

Pigs housed under artificial lighting currently experience a wide range of illuminances and photoperiods, which may be more appropriate to the visual capabilities and needs of stockpersons rather than pigs. Pigs and wild boar can show nocturnal, diurnal and crepuscular activity patterns, suggesting that their visual system may function well under a wide range of light levels, unlike humans. Inappropriate lighting affects many aspects of an animal’s physiology, anatomy and behaviour and may compromise welfare. This experiment was designed to investigate the preference of juvenile pigs to occupy and conduct certain behaviours in different illuminances, and gain some indication of their preferred photoperiod.

Evidence suggests that low social status contributes to reduced welfare in pigs (O’Connell et al., in press). It may be possible to reduce this effect by rearing pigs in enriched environments, which has previously been shown to have welfare benefits (Beattie et al., 2000). The aim of this study was to assess the effect of social status on the welfare of pigs reared in barren or enriched environments.