Environmental enrichment strategies for improved welfare of experimental layer chickens housed in isolators

The aim of this study was to reduce feather pecking in layer chickens kept in isolators for research purposes by inclusion of bunches of string and/or a sand box in a 49 day experiment in non beak trimmed SPF White Leghorn chickens. Inclusion of string from day 0 significantly reduced the incidence of feather pecking and skin injury and significantly improved (

Use of nutritional restriction at mating to dampen reproductive performance of 'FecB'-carrier merino ewes

The nutritional milieu strongly influences ovulation rate in both carriers and non-carriers of the Booroola fecundity gene ('FecB') (Montgomery et al. 1983; Kleemann et al. 1991). On the property 'Allandale' both homozygous ('FecB^BB') and heterozygous ('FecB^B+') merino ewes have large litter sizes (LSs) (2.1 and 2.3 respectively) and excessive losses from ovulation to weaning (>64%) (Walkden-Brown et al. 2007). This study reports an attempt to inhibit the expression of 'FecB' by a period of nutritional restriction, resulting in weight loss at mating

Nutritional Modulation of Resistance and Resilience to Gastrointestinal Nematode Infection: A Review

Disease susceptibility is linked to nutritional status for a wide range of human and animal diseases. Nutritional status can influence both resistance (ability to resist the pathogen) and resilience (ability to tolerate or ameliorate the effects of the pathogen). This review focuses on the nutritional modulation of gastro-intestinal nematode infection in domestic ruminants, primarily sheep. It highlights the duality of the adverse consequences of infection on host nutritional status and the adverse consequences of poor host nutritional status on resistance to infection. Central to both phenomena is the complex, gut-based immune response to gastrointestinal nematode infection. The potential for strategic nutritional supplementation to enhance host resistance and resilience is reviewed together with recent findings on responses to increased ME supply, and long term effects on host immunity of short term protein supplementation

Quantitative profiling of the shedding rate of the three Marek's disease virus (MDV) serotypes reveals that challenge with virulent MDV markedly increases shedding of vaccinal viruses

The shedding profile of Marek’s disease virus serotype 1 (MDV1, virulent), serotype 2 (MDV2, vaccinal) and herpesvirus of turkeys (HVT, vaccinal) in commercial broiler chickens was determined by measuring the daily rate of production of feather dander from chickens housed in isolators and by quantifying the viral load of each of these serotypes in the dander using quantitative real-time PCR (qPCR). MDV1 and HVT viruses were detectable in dander filtered from isolator exhaust air from day 7 and MDV2 from day 12 after infection and thereafter until the end of the experiment at 61 days of age of the chickens. There was no difference in shedding rate among the three MDV1 isolates. Daily shedding of MDV1 increased sharply between days 7 and 28 and stabilized thereafter at about 10⁹ virus copies per chicken per day, irrespective of vaccination status. Challenge with the three different MDV1 isolates markedly increased shedding of the vaccinal viruses HVT and MDV2 in dander by 38- and 75-fold, respectively. These results demonstrate the utility of qPCR for the differentiation and quantification of different MDV serotypes in feather dander and have significant implications for the routine monitoring of Marek’s disease using qPCR assays of dust, for epidemiological modelling of the behaviour and spread of MDVs in chicken populations and for studies into the evolution of virulence in MDV1 in the face of blanket vaccination with imperfect vaccines that ameliorate disease but do not prevent infection and replication of virulent virus

Effect of immunosupression on host-parasite interaction in sheep infected with 'Haemonchus contortus'

It has been recently reported that immunosuppression using methylprednisolone caused greatly increased worm burdens of 'Trichostrongylus colubriformis' and 'Teladorsagia circumcinta' with little effect in sheep performance (Greer et al., 2005a;b). This indicates that the host immune response is heavily involved in the pathological effects induced by these two parasites. This fits with the Le Jambre theory of co-evolution (Love, 2005) that sheep evolved in Asia with 'Trichostrongylus' spp. and 'Teladorsagia circumsinta' as commensals rather than parasites and that immune responses against them are an unneeded consequence of the need to develop an immune response to the far more pathogenic 'Haemonchus contortus'. Results of previous studies on immunosuppression with dexamethasone and 'H. contortus' infection have found that corticosteroids increased worm burden (Adams, 1982; 1988; Adams and Davies, 1982; Presson, Gray and Burgess, 1988). While, in once case it has been reported that corticosteroids had no effect on worm burden (Adams and Davies, 1982), most of this work did not formally test effects of immunosuppression of the pathogenesis of infection with proper control groups as used by Greer and colleagues (2005a;b), prompting the following experiment

Intensive Rotational Grazing And It's Role As A Tool For Barber's Pole Worm Control In The New England

Sheep on Farmlet C – Intensive Rotational Grazing (IRG): • have lower faecal worm egg counts than A and B in all classes of sheep • have a lower percentage of Barber’s Pole Worm ('Haemonchus contortus') • are exposed to lower numbers of larvae on pasture • have lower resistance to worms • have no discernable production losses attributable to worms The reduction in faecal worm egg counts is due to interruption of the nematode lifecycle in its free-living stages and is not due to better host resistance or resilience on Farmlet C. Intensive rotational grazing works in 2 ways: • Preventing autoinfection by removing sheep from pasture before they re-infect themselves (short grazing periods). • Presenting a low number of infective larvae available on pasture for ingestion by sheep (long rest periods). Farmlet C seems to be more effective against Barber’s Pole worm than against the other major worm species. This is likely, due to the specific climatic conditions required by Barber’s Pole worm eggs to hatch and develop into infective larvae. Other major worm species such as Black scour worm ('Trichostrongylus spp.') and Small brown stomach worm ('Teladorsagia circumcincta') have much hardier eggs which can survive longer in the absence of optimal moisture and temperature conditions

One dog's meat is another dog's poison - nutrition in the Dalmatian dog

Dalmatian dogs have a predisposition to urate urolithiasis due to a metabolic defect inherent in this breed. It has been suggested that feeding low-protein diets can reduce the risk of producing urate calculi in these dogs, but caution must be exercise d to ensure that adequate nutrient requirements are met. This paper discusses the results of a recent feeding trial in which Dalmatian dogs were fed one of four commercial diets, or an anti-uric acid (vegetarian) diet, or an all-meat diet. The crude protein content of these diets ranged from 9.5% to 62.5% in dry matter. Dalmatian dogs produced significantly lower amounts of precipitates in their urine when fed low-protein diets than when they were fed premium high-protein diets or meat. A commercial dry dog food with a crude protein content of 15% was found to be the most effective at reducing urinary precipitates, and equally effective as the special anti-uric acid diet. The effects of time and frequency of feeding were also found to be significant factors in the formation of urinary precipitates in Dalmatian dogs. Dogs produced the lowest levels of urinary precipitates when they were fed a single meal offered late in the day

Interaction between the effects of evaporation rate and amount of simulated rainfall on development of the free-living stages of 'Haemonchus contortus'

A factorial experiment (3 x 4 x 2 x 3) was conducted in programmable incubators to investigate interaction between the effects of rainfall amount, rainfall distribution and evaporation rate on development of 'Haemonchus contortus' to L3. Sheep faeces containing H. 'contortus' eggs were incubated on sterilised soil under variable temperatures typical of summer in the Northern Tablelands of NSW, Australia. Simulated rainfall was applied in 1 of 3 amounts (12, 24 or 32 mm) and 4 distributions (a single event on the day after deposition, or the same total amount split in 2, 3 or 4 equal events over 2, 3 or 4 days, respectively). Samples were incubated at either a Low or High rate of evaporation (Low: 2.1–3.4 mm/day and High: 3.8–6.1 mm/day), and faeces and soil were destructively sampled at 4, 7 and 14 days post-deposition. Recovery of L3 from the soil (extra-pellet L3) increased over time (up to 0.52% at day 14) and with each increment of rainfall (12 mm

Ecology of the free-living stages of major trichostrongylid parasites of sheep

Significant developments over recent decades make it timely to review the ecology of the major gastrointestinal nematode (GIN) species of sheep. These include the relentless development and spread of anthelmintic resistance in all of the major sheep production regions of the world, and the consequent drive towards integrated parasite management (IPM) systems incorporating non-chemotherapeutic strategies such as grazing management. The success of such programs is dependent on a detailed understanding of the environmental influences on the free-living stages of the nematode life cycle. Major reviews of the subject were conducted prior to 1980, however considerable work has been completed since, including the development of mathematical models describing the epidemiology of GIN infection. Knowledge of the temperature thresholds for free-living development has also improved, while investigations of moisture influences and interactions with temperature have allowed more effective exploitation of environmental effects for IPM. This review re-evaluates our understanding of the factors that determine the success or failure of the free-living phases of the life cycle in light of these developments. Temperature and moisture are the dominant influences on the free-living stages of 'Haemonchus contortus', 'Teladorsagia circumcincta' and 'Trichostrongylus colubriformis', with the effects of pasture conditions playing a significant modulating role. Early in the free-living phase, the developmental success of the three GIN species is limited by susceptibility to cold temperatures. In general, 'H. contortus' is most susceptible, followed by 'T. colubriformis' and then 'T. circumcincta'. The length of the development cycle is dependent largely on temperature, with development rate increasing at warmer temperatures. However, in order for development to proceed to the infective larval stage, addition of moisture is generally required. There has been considerably less work quantifying the effects of moisture on free-living development, although it is clear that H. contortus is most susceptible to desiccation during the pre-infective stages. Once the infective stage is reached, the influences of temperature and moisture on survival are less important, resulting in considerable survival times under conditions lethal to pre-infective stages. However, hot, dry conditions can be lethal for infective larvae of all three species, while extreme cold is also lethal with significant species variation. While the existing body of knowledge is substantial, the interpretation of many studies and comparison between them is complicated by inadequate description of, or variation in, the environmental measurements used. Confounding the effects of environmental variables on development to infective stage is the migration of larvae from the faeces and subsequent survival on pasture. There is a need to build on recent efforts to explore interaction between the effects of temperature and moisture, and also the trend to more closely simulate field conditions in laboratory studies. We propose a logical framework for future ecological investigations to overcome some of these problems, facilitate the development of a more integrated dataset on the subject and improve prediction of free-living development

Dietary Enhancement of Resistance to 'Trichostrongylus colubriformis' in Merino Weaners

This research was conducted to determine whether short and long-term resistance of Merino weaners to infection from 'T. colubriformis' could be manipulated by a brief period of differential feeding. Merino weaners infected with 'T. colubriformis' for 10 weeks were restrictively fed diets to create 2 levels of digestible energy intake and 2 levels of metabolisable protein supply. Live weight reflected energy and protein supply and at the conclusion of the 10 weeks of infection there was a 4.8 kg difference between animals fed greatest and least levels of digestible energy and metabolisable protein supply. Neither digestible energy intake nor metabolisable protein supply affected faecal egg count. Total counts of 'T colubriformis' determined 10 weeks post infection were significantly lower in animals with greater levels of digestible energy intake but were unaffected by metabolisable protein supply. This research has demonstrated a novel finding that increased digestible energy intake enhances resistance to 'T. colubriformis' in young sheep