Rapeseed napin and cruciferin are readily digested by poultry.

Rapeseed proteins have been considered as being poorly digestible in the gut of non-ruminants. The aim of the study was to assess the digestibility of napin and cruciferin in ileal digesta of broiler chickens, testing sixteen samples of rapeseed co-products with protein levels ranging from 293 g/kg to 560 g/kg dry matter. Each sample was included into a semi-synthetic diet at a rate of 500 g/kg and evaluated with broiler chickens in a randomised design. Dietary and ileal digesta proteins were extracted and identified by gel-based liquid chromatography-tandem mass spectrometry (LC-MS/MS). Three isomers of napin (a 2S albumin) and nine cruciferins (an 11S globulin) were identified in the rapeseed co-products, whereas six endogenous enzymes such as trypsin (I-P1, II-P29), chymotrypsin (elastase and precursor), carboxypeptidase B and α-amylase were found in the ileal digesta. It is concluded that as none of the rapeseed proteins were detected in the ileal digesta, rapeseed proteins can be readily digested by broiler chickens, irrespective of the protein content in the diet.

The feeding of heather (Calluna vulgaris) to Teladorsagia circumcincta infected lambs reduces parasitism but can detrimentally impact performance.

Gastrointestinal nematode (GIN) infections impact small ruminant health, welfare, and production across farming systems. Rising anthelmintic resistance and regulation of synthetic drug use in organic farming is driving research and development of sustainable alternatives for GIN control. One alternative is the feeding of plants that contain secondary metabolites (PSMs) e.g., proanthocyanidins (PA, syn. condensed tannins) that have shown anthelmintic potential. However, PSMs can potentially impair performance, arising from reduced palatability and thus intake, digestibility or even toxicity effects. In this study, we tested the trade-off between the antiparasitic and anti-nutritional effects of heather consumption by lambs. The impact of additional feeding of a nematophagous fungus (Duddingtonia flagrans) on larval development was also explored. Lambs infected with Teladorsagia circumcincta or uninfected controls, were offered ad libitum heather, or a control chopped hay for 22 days during the infection patent period. Eight days into the patent period, parasitised lambs were supplemented (or remained unsupplemented) with D. flagrans for a 5-day period. Performance and infection metrics were recorded, and polyphenol levels in the heather and control hay were measured to investigate their association with activity. The lambs consumed heather at approximately 20% of their dry matter intake, which was sufficient to exhibit significant anthelmintic effects via a reduction in total egg output (P = 0.007), compared to hay-fed lambs; the magnitude of the reduction over time in heather fed lambs was almost 10-fold compared to control lambs. Negative effects on production were shown, as heather-fed lambs weighed 6% less than hay-fed lambs (P < 0.001), even though dry matter intake (DMI) of heather increased over time. D. flagrans supplementation lowered larval recovery in the faeces of infected lambs by 31.8% (P = 0.003), although no interactions between feeding heather and D. flagrans were observed (P = 0.337). There was no significant correlation between PA, or other polyphenol subgroups in the diet and egg output, which suggests that any association between heather feeding and anthelmintic effect is not simply and directly attributable to the measured polyphenols. The level of heather intake in this study showed no antagonistic effects on D. flagrans, demonstrating the methods can be used in combination, but provide no additive effect on overall anthelmintic efficacies. In conclusion, heather feeding can assist to reduce egg outputs in infected sheep, but at 20% of DMI negative effects on lamb performance can be expected which may outweigh any antiparasitic benefits.

Sensitivity of broiler performance, organ weights and plasma constituents to amino acid supplementation and reused litter exposure using ideal protein-formulated rations.

Effects of amino acid supplementation to ideal protein (IP) formulated rations were investigated on growth performance, plasma metabolites and organ weights of broilers placed on 100% recycled (reused) litter. Day-old Ross308 male broilers were raised on either clean or reused litter and fed for three weeks on one of five isoenergetic diets, where an IP-based control diet (C) was compared with diets containing threonine (T) or arginine (A) at 25% above requirements, or with 1% supplemented glutamine (G), or with each amino acid added (TAG). Litter and diet treatments did not strongly interact on outcomes. Reused litter placement resulted in greater weight gain, smaller feed conversion ratio and heavier bursal weights (P < 0.05) compared to clean litter placement. Relative to C and T birds, TAG birds reduced weight gain and feed intake (P < 0.05). Plasma uric acid levels in G birds were greater than in C, T and A birds (P < 0.001). Collectively, since the outcomes of placement on reused litter increased performance and the control diet was IP formulated, the absence of increased growth performance in response to amino acid supplementation would be consistent with amino acids tested being excess to requirements.

Immunomodulatory effects of dietary protein during Nippostrongylus brasiliensis re-infection in lactating rats.

Periparturient relaxation of immunity (PPRI) to secondary infection with nematodes is believed to have a nutritional basis due to differential partitioning of scarce nutrient resources, particularly protein, to reproductive rather than immune functions. At times of protein scarcity, an increase in protein supply has been reported to assuage this phenomenon. The Nippostrongylus brasiliensis reinfected lactating rat model is now being utilized to investigate the immune reactions underlying the modifying role of dietary protein on PPRI. Herein, we demonstrate that lactating rats reinfected with N. brasiliensis under high protein (HP) dietary conditions exhibit decreased worm burdens and reduced colon egg counts compared to their low protein (LP) counterparts. These reductions correlated with increased mastocytosis and greater goblet cell hyperplasia. Additionally, the local antibody profile revealed that HP reinfected lactating rats developed a stronger antigen specific IgG2b response earlier in infection in comparison with their LP counterparts. Our study provides evidence that increased dietary protein content reduces the PPRI to N. brasiliensis re-infection in the lactating rat through improved mucosal immune responses.

Genetic growth potential interacts with nutrition on the ability of mice to cope with Heligmosomoides bakeri infection.

Artificial selection for improved productivity may reduce an animal's ability to cope with pathogens. Here, we used Roslin mice, uniquely divergently selected for high (ROH) and low (ROL) body weight, to assess interactive effects of differing growth potential and protein nutrition on host resilience and resistance. In a 2 x 2 x 6 factorial design, ROH and ROL mice were either sham-infected or infected with 250 L(3)Heligmosomoides bakeri and fed diets with 30, 80, 130, 180, 230 and 280 g crude protein per kg. The infected ROL-30 treatment resulted in clinical disease and was discontinued. In the remaining ROL mice, infection and feeding treatments did not affect growth but infection reduced weight gain in ROH-30, ROH-80 and ROH-130 mice. Although infection resulted in temporarily reduced food intake (anorexia) in both mouse lines, mean food intake over the whole experiment was reduced in ROH mice only. ROH mice excreted more worm eggs and had higher worm burdens, with relatively fewer female worms, than ROL mice. However, these resistance traits were not sensitive to dietary protein. These results support the view that selection for high growth may reduce the ability to cope with pathogens, and that improved protein nutrition may to some extent ameliorate this penalty.

TYPLEX® Chelate, a novel feed additive, inhibits Campylobacter jejuni biofilm formation and cecal colonization in broiler chickens.

Reducing Campylobacter spp. carriage in poultry is challenging, but essential to control this major cause of human bacterial gastroenteritis worldwide. Although much is known about the mechanisms and route of Campylobacter spp. colonization in poultry, the literature is scarce on antibiotic-free solutions to combat Campylobacter spp. colonization in poultry. In vitro and in vivo studies were conducted to investigate the role of TYPLEX® Chelate (ferric tyrosine), a novel feed additive, in inhibiting Campylobacter jejuni (C. jejuni) biofilm formation and reducing C. jejuni and Escherichia coli (E. coli) colonization in broiler chickens at market age. In an in vitro study, the inhibitory effect on C. jejuni biofilm formation using a plastic bead assay was investigated. The results demonstrated that TYPLEX® Chelate significantly reduces biofilm formation. In an in vivo study, 800 broilers (one d old) were randomly allocated to 4 dietary treatments in a randomized block design, each having 10 replicate pens with 20 birds per pen. At d 21, all birds were challenged with C. jejuni via seeded litter. At d 42, cecal samples were collected and tested for volatile fatty acid (VFA) concentrations and C. jejuni and E. coli counts. The results showed that TYPLEX® Chelate reduced the carriage of C. jejuni and E. coli in poultry by 2 and 1 log10 per gram cecal sample, respectively, and increased cecal VFA concentrations. These findings support TYPLEX® Chelate as a novel non-antibiotic feed additive that may help produce poultry with a lower public health risk of Campylobacteriosis.

Ubiquitous parasites drive a 33% increase in methane yield from livestock.

Of anthropogenic methane emissions, 40% can be attributed to agriculture, the majority of which are from enteric fermentation in livestock. With international commitments to tackle drivers of climate change, there is a need to lower global methane emissions from livestock production. Gastrointestinal helminths (parasitic worms) are globally ubiquitous and represent one of the most pervasive challenges to the health and productivity of grazing livestock. These parasites influence a number of factors affecting methane emissions including feed efficiency, nutrient use, and production traits. However, their effects on methane emissions are unknown. This is to our knowledge the first study that empirically demonstrates disease-driven increases in methane (CH4) yield in livestock (grams of CH4 per kg of dry matter intake). We do this by measuring methane emissions (in respiration chambers), dry matter intake, and production parameters for parasitised and parasite-free lambs. This study shows that parasite infections in lambs can lead to a 33% increase in methane yield (g CH4/kg DMI). This knowledge will facilitate more accurate calculations of the true environmental costs of parasitism in livestock, and reveals the potential benefits of mitigating emission through controlling parasite burdens.

Animal health and greenhouse gas intensity: the paradox of periparturient parasitism.

Here we provide the first known direct measurements of pathogen challenge impacts on greenhouse gas production, yield and intensity. Twin-rearing ewes were ad libitum fed pelleted lucerne from day -32 to 36 (day 0 is parturition), and repeatedly infected with 10,000 Teladorsagia circumcincta infective larvae (n=16), or sham-dosed with water (n=16). A third group of 16 ewes were fed at 80% of uninfected ewes' feed intake during lactation. Methane emissions were measured in respiration chambers (day 30-36) whilst total tract apparent nutrient digestibility around day 28 informed calculated manure methane and nitrous oxide emissions estimates. Periparturient parasitism reduced feed intake (-9%) and litter weight gain (-7%) and doubled maternal body weight loss. Parasitism reduced daily enteric methane production by 10%, did not affect the methane yield per unit of dry matter intake but increased the yield per unit of digestible organic matter intake by 14%. Parasitism did not affect the daily calculated manure methane and nitrous oxide production, but increased the manure methane and nitrous oxide yields per unit of dry matter intake by 16% and 4%, respectively, and per unit of digestible organic matter intake by 46% and 31%, respectively. Accounting for increased lucerne input for delayed weaning and maternal body weight loss compensation, parasitism increased the calculated greenhouse gas intensity per kg of lamb weight gain for enteric methane (+11%), manure methane (+32%) and nitrous oxide (+30%). Supplemented with the global warming potential associated with production of pelleted lucerne, we demonstrated that parasitism increased calculated global warming potential per kg of lamb weight gain by 16%, which was similar to the measured impact of parasitism on the feed conversion ratio. Thus, arising from a pathogen-induced feed efficiency reduction and modified greenhouse gas emissions, we demonstrated that ovine periparturient parasitism increases greenhouse gas intensity. This implies that ewe worm control can not only improve production efficiency but also reduce the environmental footprint of sheep production systems.

Investigations of the nutritive value of meals of double-low rapeseed and its influence on growth performance of broiler chickens.

Four experiments were carried out to study the possible differences in metabolizable energy (ME) of meals (RSM) or expeller meals (RSE) from double-low rapeseed (Expt. 1), the influence of processing on ME (Expt. 2) and on relative phosphorus (P) bioavailability (Expt. 3) in RSM, and effect of RSM inclusion on growth performance of broilers (Expt. 4). For Expt. 1, diets with 300 g/kg RSM from 11 RSM and 4 RSE varieties were fed to broilers from d 14 to 21, with excreta collection on d 19 to 21. Each treatment had 8 replicates and 3 birds per replicate. Energy metabolizability of RSM of a specialized high glucosinolate variety (V275OL) was greater (P < 0.05) than all the other varieties. In Expt. 2, two RSM varieties were processed with mild or conventional processing condition. There were no variety effects on ME, but ME and MEn were greater (P < 0.01) for RSM processed by mild processing condition. In Expt. 3, P bioavailability of RSM was determined, relative to MSP, using growth performance and tibia ash as responses. Phosphorus relative bioavailability values were greater (P < 0.05) in RSM of DK Cabernet variety processed using the mild processing condition. In Expt. 4, two RSM varieties were added to wheat-soybean meal-based diet at the rates of 50, 100, 150, or 200 g/kg and fed to broilers from d 0 to 42. Inclusion of 150 and 200 g/kg of RSM resulted in reduced weight gain and increased feed conversion ratio (FCR) compared (P < 0.01) with the lower inclusion levels during the starter phase. For the entire trial (d 0 to 42), weight gain was greater (P < 0.01) for birds receiving diets with RSM from PR46W21 variety. It was concluded from the experiments that apart from the residual ether extract content, variety differences had no impact on ME of RSM, conventional processing reduced ME and relative bio-availability of P; and that the maximum level of RSM inclusion depends on maximum growth performance level desired.

Rapid improvement of immunity to Teladorsagia circumcincta is achieved through a reduction in the demand for protein in lactating ewes.

Protein supplementation can improve the resistance to parasites of periparturient ewes, as indicated by reduced nematode egg excretion and worm burdens. However, the rate at which this improvement can occur is largely unknown. We investigated the rate of improvement by assessing temporal changes in faecal egg counts after we experimentally reduced nutrient demand. Three groups of nine pregnant ewes each were trickle infected with Teladorsagia circumcincta from day(-70) to day(16) (parturition is day0). Two groups of twin-rearing ewes were fed at 0.8 (L22) or 1.2 (H22) times their assumed metabolizable protein requirements, and a third group was fed the same daily food allowances as L22 ewes, but one of their lambs was removed on day10 (L21). Ewes were slaughtered on day21 to assess worm burdens, in vitro larval establishment on abomasal explants, and mucosal inflammatory cells. Faecal egg counts of L22 ewes were higher than H22 ewes throughout lactation. After the removal of one lamb, faecal egg counts of L21 ewes decreased within 5 days to levels similar to H22 ewes. Relative to L22 ewes, L21 and H22 ewes had lower worm burdens, parasite per capita fecundity and in vitro establishment rates of both T. circumcincta and Haemonchus contortus. Mucosal mast cell and eosinophil counts were similar for all ewes, but H22 ewes had higher globule leukocyte counts than L22 and L21 ewes. The data suggest that a reduction in protein demand can rapidly improve periparturient immunity to T. circumcincta. This may be associated with increased parasite expulsion, reduced fecundity and non-parasite specific reduction of in vitro larval establishment.

Effects of protein supply and reproductive status on local and systemic immune responses to Teladorsagia circumcincta in sheep.

The effects of protein supply and reproductive status on circulating antibody responses and local inflammatory cell counts were investigated in parasitized sheep, with local immune responses assessed through a recently refined abomasal cannulation methodology. We hypothesized that if breakdown of immunity has a nutritional basis, then protein scarcity would result in a breakdown of immunity to Teladorsagia circumcincta in both periparturient and non-reproducing (barren) ewes. Twin-bearing and barren, abomasally cannulated ewes were fed at either 0.8 or 1.3 times protein requirements from 3 weeks before until 6 weeks after parturition (n = 6). All sheep were trickle infected at a rate of 10,000 infective larvae (L3) per day, for 3 days per week throughout the experiment. Faecal egg counts remained virtually zero in all barren ewes, whilst protein supplementation reduced faecal egg counts in the periparturient ewes during most of the periparturient period. Final worm burdens, taken at 6 weeks into lactation, were lower for the barren ewes than for the lactating ewes, whilst protein supplementation reduced worm burdens in the latter. Protein supply did not affect mucosal mast cell counts, which were consistently higher for the barren ewes than the periparturient ewes, but were temporarily decreased around parturition. Barren ewes and protein supplemented lactating ewes had higher globule leukocyte counts than the unsupplemented lactating ewes. Protein supplementation increased eosinophil counts in the lactating ewes though only during the later part of the lactation period. Plasma IgA anti-L3 antibody was similar for all ewes, but IgE anti-L3 antibody was higher for the protein supplemented periparturient ewes compared to the unsupplemented periparturient ewes and all barren ewes. It is likely that the combination of low protein requirements and large body protein reserves did not result in breakdown of immunity to T. circumcincta for the barren ewes. These results suggest that changes in mucosal mast cell and eosinophil counts are not necessarily associated with changes in host resistance to T. circumcincta. However, the data support the view that increased globule leukocyte counts and plasma IgE anti-L3 antibody may be associated with nutritionally improved expression of immunity in periparturient ewes.

Influence of dietary protein supply on resistance to experimental infections with Haemonchus contortus in Ile de France and Santa Ines lambs.

The effect of Haemonchus contortus infection in sheep fed with a moderate and high protein content diet was evaluated in two breeds of sheep. Forty-eight Ile de France and Santa Ines lambs were maintained indoors since birth, in worm-free conditions. The lambs were allocated after weaning in four groups of six animals per breed, which were either infected or remain uninfected and given access to either a moderately or highly metabolizable protein diet. The moderately and highly metabolizable protein diets were calculated to supply 75 and 129 g metabolizable protein per kg of dry matter (MP/kg DM), respectively. The infection consisted of a trickle infection with 300 infective larvae, three times a week, for 12 weeks. Significant differences were observed for mast cell, globule leukocyte and eosinophil counts in the abomasal mucosa of the infected groups compared to the control of both breeds (P<0.05), regardless of the diet supplied. Significantly higher IgA anti-L5 antibody was detected in the infected Santa Ines groups than in the infected Ile de France groups (P<0.05). Increased metabolizable protein supply resulted in larger body weight gain and higher packed cell volumes for both breeds (P<0.05). Both breeds showed an increased ability to withstand the pathophysiological effects of H. contortus infection when given access to the highly metabolizable protein diet. However, increased metabolizable protein supply resulted in reduced worm burdens in Santa Ines lambs but not in the Ile de France lambs (P<0.05). The present results show that the increase in protein content in growing lamb diets may benefit resistance and resilience to gastrointestinal parasites but that these benefits may vary among breeds.

Is the allocation of metabolisable protein prioritised to milk production rather than to immune functions in Teladorsagia circumcincta-infected lactating ewes?

It has been suggested that the periparturient breakdown of immunity to parasites has a nutritional basis. Our overall hypothesis is that it results from a prioritised scarce nutrient allocation to reproductive functions (e.g. milk production) rather than to immune functions. We tested this hypothesis by offering five levels of dietary metabolisable protein, ranging from 0.65 to 1.25 times their assumed requirements, for 4 weeks post-parturition to twin-rearing Greyface ewes, experimentally infected with Teladorsagia circumcincta. We hypothesised that the initial increments of metabolisable protein supply would increase milk production without affecting the degree of breakdown of immunity whilst later increments would reduce the degree of breakdown of immunity. The first two increments of metabolisable protein supply indeed increased milk production and did not affect final worm burdens, but in contrast to the expectation, reduced faecal egg counts and total egg output. The last two increments of metabolisable protein supply did not further affect milk production and egg output, but resulted in reduced final worm burdens. Metabolisable protein supply did not affect plasma IgG and IgE antibody against somatic L(3) antigen but the first three increments reduced plasma pepsinogen and plasma IgA antibody. The last increment did not further reduce plasma pepsinogen but increased plasma IgA. Metabolisable protein supply did not systematically affect abomasal mucosal mast cell, globule leukocyte and eosinophil counts. Our results support the view that the priority of scarce metabolisable protein allocation to milk production over immune functions may be gradual rather than absolute. The contrast between effects of metabolisable protein supply on faecal egg count and final worm burden points towards the possibility that if different effector responses regulate fecundity and worm expulsion, then they would differ in their sensitivity towards changes in the degree of nutrient scarcity.

The sequential analysis of local inflammatory cells during abomasal nematode infection in periparturient sheep.

A technique to take sequential tissue biopsy samples in multiparous, periparturient ewes from the abomasal mucosa is described, developed in parallel in Scotland and New Zealand. Samples were extracted via abomasal cannulae inserted into the wall of the abomasum and exteriorised through dorso-ventral laparotomy. Animals recovered quickly post-surgery, and tolerated the cannula and sampling without any adverse signs of pain or discomfort. The technique was deployed in two pilot studies to investigate the sequential mucosal inflammatory cell responses in well-defined parasitological models, during the periparturient relaxation of immunity in ewes infected with gastrointestinal nematodes and subjected to different feeding treatments. One experiment (Moredun Research Institute, Scotland) involved the infection of twin-bearing ewes with Teladorsagia circumcincta L3 either before, or after lambing. By feeding ewes with different levels of protein supplementation, preliminary data on the impact of nutrition on the eosinophil, mucosal mast cell and globule leucocyte responses during this period were investigated. A similar study was also performed at Lincoln University, New Zealand, to investigate these cell responses in sheep fed relatively high or low protein diets during pregnancy, and infected with a combined immunisation regime of T. circumcincta and Trichostrongylus colubriformis L3. These studies confirmed the phenomenon termed the periparturient relaxation in immunity (PPRI) where a transitory increase in faecal egg counts is observed during late pregnancy and lactation, and this effect was exacerbated during protein undernutrition. Although the number of animals was low in each experiment and the cell responses variable, the results together suggest a reduction in the number of mucosal mast cells and globule leucocyte during the PPRI when protein supply was restricted. The present paper thus describes a successful technique to monitor ovine mucosal cell populations during local immune responses in normal and pregnant sheep. It is envisaged that this technique will be a powerful adjunct to investigations into mucosal immune mechanisms and disease pathogenesis, and will be employed to confirm the influence of dietary protein on the local inflammatory cell responses during the PPRI.

Effects of dietary inclusion of pea and faba bean as a replacement for soybean meal on grower and finisher pig performance and carcass quality.

To reduce reliance on imported soybean meal (SBM) in temperate environments, pea and faba bean may be alternative protein sources for pig diets. We assessed the effects of dietary pea and faba bean inclusion on grower and finisher pig performance and carcass quality. There were 9 dietary treatments tested on both grower (30 to 60 kg) and finisher (60 to 100 kg) pigs in a dose response feeding trial. The control diet included SBM at 14 and 12% for grower and finisher pigs, respectively, whereas in the test diets, pea or faba bean were included at 7.5, 15, 22.5, and 30%, gradually and completely replacing SBM. Diets were formulated to be isoenergetic for NE and with the same standard ileal digestible Lys content. After a 1-wk adaptation period, each diet was available on an ad libitum basis to 4 pens of pigs with 4 pigs per pen (2 entire males and 2 females) for 4 wk. Weekly BW for individual pigs, and pen intakes were recorded to assess ADG, ADFI, and G:F. Finisher pigs were then slaughtered at a commercial slaughter house to record carcass quality and assess skatole and indole concentration in the backfat. There were no effects (P > 0.10) on grower ADG, ADFI, and G:F, but pulse inclusion reduced finisher ADG (P = 0.04), with a quadratic effect of pulse inclusion (P = 0.03), as ADG tended to be reduced over initial inclusion levels only. There were no associated effects (P > 0.10) on ADFI or G:F, and pea and faba bean diets resulted in similar finisher performance. Increasing pulse inclusion linearly increased fecal DM content both in grower pigs (P = 0.02) and finisher pigs (P < 0.01). There were no effects on carcass quality or backfat skatole concentrations, but indole concentration was linearly reduced with increasing pulse inclusion (P = 0.05). It is concluded that pea and faba bean may be a viable alternative to SBM in grower and finisher pig diets.

Sensitivity of periparturient breakdown of immunity to parasites to dietary protein source.

Effects of increased MP supply on the degree of periparturient relaxation of immunity (PPRI) in sheep may be dependent on quality of supplied MP. Here we tested the hypothesis that additional MP supply from rations based on xylose-treated soybean meal would be more effective than from rations based on faba beans in reducing the degree of PPRI, as indicated by nematode egg excretion. Twenty-four multiple-bearing ewes were trickle infected with Teladorsagia circumcincta larvae from d -56 to d 31 relative to start of lactation (d 0). From d -26 onwards, ewes were fed at either 0.8 (LP) or at 1.2 times their respective calculated MP requirements using either xylose-treated soybean (HPS) or faba beans (HPB). Litter size was adjusted to 2 lambs at parturition. Feeding treatments did not affect nematode egg excretion, ewe BW or BCS during late pregnancy (P > 0.10), but HPS and HPB ewes had reduced plasma pepsinogen concentrations (P = 0.003). During lactation, HPS and HPB feeding increased ewe BW gain (P < 0.001) and BCS (P = 0.017), and reduced plasma pepsinogen concentrations (P = 0.008) to the same extent, compared with LP feeding. However, only HPS feeding increased litter weight gain (P = 0.017) and reduced nematode egg excretion (P = 0.015), which were both similar between HPB and LP (P > 0.10). The results support the view that extra MP supply from xylose-treated soybean based rations is more effective in reducing parasitism than MP from faba bean-based rations, suggesting that protein source and/or quality are important factors to consider for the nutritional control of parasitism.

Amelioration of the periparturient relaxation of immunity to parasites through a reduction in mammalian reproductive effort.

The degree of periparturient relaxation of immunity to gastrointestinal parasites has a nutritional basis, as overcoming protein scarcity through increased protein supply improves lactational performance, enhances local immune responses and reduces worm burdens. Herein lactating rats, re-infected with Nippostrongylus brasiliensis, are used to test the hypothesis that a similar and rapid improvement of immunity can be achieved through reducing nutrient demand at times of dietary protein scarcity. Reducing litter size from 12 to three pups during lactation resulted, as expected, in cessation of maternal body weight loss and increased pup body weight gain compared with dams which continued to nurse 12 pups. This increase in performance concurred with a rapid decrease in parasitism; within 3 days post nutrient reduction, a 87% reduction in the number of worm eggs found in the colon and 83% reduction in worm burdens was observed, which concurred with increased local immune responses, i.e. 70% more mast cells and 44% more eosinophils in the small intestinal mucosa, to levels similar to those in dams nursing three pups throughout. However, there were no concurrent changes in goblet cell hyperplasia, serum anti-N. brasiliensis-specific antibody levels or mRNA expression of IL-4, IL-10 or IL-13 in the mesenteric lymph nodes. To our knowledge the current study is the first to employ a litter reduction strategy to assess the rate of immune improvement upon overcoming nutrient scarcity in a non-ruminant host. These data support the hypothesis that periparturient relaxation of immunity to gastrointestinal nematodes can be reduced by restoring nutrient adequacy and, importantly, that this improvement can occur very rapidly.

Dissecting the impact of protein versus energy host nutrition on the expression of immunity to gastrointestinal parasites during lactation.

Many mammals exhibit a periparturient relaxation of previously established immune responses (PPRI) to gastrointestinal nematodes culminating in increased worm burdens. It has been suggested that the extent of PPRI may have a nutritional basis as it is considerably augmented when protein supply is scarce. Subsequent studies have shown that increased dietary protein intake can ameliorate this phenomenon. However, this effect is often confounded with increased food intake and thus increased energy levels. Herein, we aimed to dissect the effects of protein and energy nutrition on the immune status and resistance to re-infection with gastrointestinal nematodes in the periparturient host. The lactating, Nippostrongylus brasiliensis re-infected rat was utilised as an established model for mammalian PPRI. Experimental animals were assigned to restricted feeding regimens designed to achieve four pre-determined levels of crude protein (CP) at one of two levels of metabolisable energy (ME) and parasitological and immunological measurements taken at either day 6 or day 9 post re-infection. We clearly show that increased supply of dietary CP, but not increased dietary ME, significantly reduced worm burdens. The increased magnitude of worm expulsion with increased dietary CP supply strongly correlated with mucosal mast cell accumulation in the small intestine. In addition, increased CP and not ME supply increased mucosal eosinophil numbers. Furthermore, increased CP led to higher levels of total IgG at high ME only and there were interactive effects of CP and ME on serum levels of IgG1 and IgG2a. Perhaps surprisingly, CP nutrition did not affect expression of either Th1 (IFN-γ) or Th2 (IL-4, IL-13) cytokines in the mesenteric lymph nodes. These data emphasise the role of immunonutrition, and particularly dietary protein, in combating infectious disease such as gastrointestinal parasitism.

Influence of protein supplementation during late pregnancy and lactation on the resistance of Santa Ines and Ile de France ewes to Haemonchus contortus.

This experiment aimed to evaluate the effect of periparturient metabolizable protein (MP) nutrition on resistance to Haemonchus contortus in single rearing Ile de France and Santa Ines ewes. The restriction-fed iso-energetic diet was calculated to provide either 0.8 (low MP diet) or 1.3 (high MP diet) times MP, from three weeks before parturition until eight weeks into lactation. The ewes were experimentally infected with 1000 H. contortus infective larvae (L3) three times a week (Mondays, Wednesdays and Fridays), starting five weeks before the predicted date for parturition until a total of 15,000 L3 had been administered. While both breeds showed elevated fecal egg counts (FEC), these values were significantly lower for Santa Ines ewes than Ile de France ewes, but were independent of level of MP feeding. The latter also did not affect lamb weight gain and ewe body weight variation in each breed. Packed cell volume and total plasma protein for Santa Ines in all periods were significantly higher than those for Ile de France ewes (P<0.01) but were not affected by nutrition. In contrast, levels of serum IgG and IgA antibodies against somatic H. contortus infective larvae and adult antigens were similar between breeds but higher in animals that received high MP diets (P<0.05). The reduced body score of ewes at the beginning of the experiment probably influenced their high susceptibility to incoming larvae. Since, unexpectedly, MP scarcity was not achieved in this experiment, our data support the view that Santa Ines ewes are more resistant to H. contortus than Ile de France ewes.

Effects of maternal protein nutrition and subsequent grazing on chicory (Cichorium intybus) on parasitism and performance of lambs.

Forty-eight 4- to 5-yr-old Blackface x Bluefaced Leicester (Mule) ewes and their 24-d-old twin lambs were used to assess the effects of maternal protein nutrition and subsequent grazing on chicory (Cichorium intybus) on performance and parasitism. The experiment consisted of 2 grazing periods: safe pasture period and experimental pasture period. During an adaptation period of 66 d, ewes were infected through oral dosing with Teladorsagia circumcincta infective larvae (3 d per wk) and were supplemented with protein (HP) or not (LP) for the last 45 d of this period. At the end of this period, ewes and their lambs were turned out onto a parasitologically safe pasture; all ewes continued to be dosed with parasite (once a week), and HP ewes received protein supplementation for the first 35 d. Ewes and lambs grazed the safe pasture for an additional 43 d after termination of protein supplementation and of oral dosing with parasites. Ewes and their lambs were then moved onto newly established experimental pastures sown with chicory or grass/clover (Lolium perenne/Trifolium repens). During the safe pasture period, HP ewes had decreased fecal egg counts (FEC) compared with LP ewes, whereas HP lambs had temporarily less (P < 0.05) FEC, decreased (P < 0.001) plasma pepsinogen concentrations, and grew faster (P = 0.028) than LP lambs. Lambs grazing chicory had consistently less (P < 0.001) FEC and grew faster (P = 0.013) than lambs grazing grass/clover but had greater (P < 0.001) concentrations of pepsinogen. Pasture larvae counts were decreased (P = 0.07) for the chicory compared with the grass/clover plots. There were no interactions (P > 0.10) between maternal nutrition and grazed forage type on performance or parasitological measurements. Our results suggest that increased maternal protein nutrition and subsequent grazing of chicory independently improve lamb performance and reduce lamb parasitism.