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There has been an increasing focus on the role of antioxidants for human health. This review outlines associations of the most predominant antioxidant, glutathione (GSH), in the body and some ageing-related diseases. Strategies to replete GSH, particularly developing animal-source food products, are discussed. Potentials to alter GSH content in the animal's body and its possible effects on health are also explored.

Fecal egg count (FEC) has been widely used as an indicator of host resistance to gastrointestinal parasites in sheep and has been shown to be a heritable trait. Two other possible indicators of parasites, dag score (DS; accumulated fecal material) and fecal consistency score (FCS), were investigated in this study, along with BW. All four traits were studied to see how heritability and genetic correlations varied with age from weaning (4 mo) to hogget age (approximately 400 d). More than 1,100 lambs, the offspring of 37 rams, were recorded eight times between weaning (3 to 5 mo of age) and hogget age (13 to 18 mo of age) on two farms. Sire models were fitted to the data from each trait at each recording and in a repeatability model involving the whole data set. Overall, the heritabilities were 0.28 ± 0.072 (FEC), 0.11 ± 0.036 (DS), 0.12 ± 0.036 (FCS), and 0.23 ± 0.070 (BW). By fitting random regression models to the time-series data, it was possible to see how these heritability values varied as the lambs aged, from weaning to hogget age. The heritability of FEC rose from 0.2 at weaning to 0.65 at 400 d. Dag score had a higher heritability (0.25) in the middle of the age range and a low value at weaning (<0.1) and hogget age (0.16). The heritability of FCS was low, with a value of 0.2 at weaning reducing to 0.05 as the animals aged. Body weight had zero heritability at weaning, which rose to greater than 0.6 at hogget age. Most traits had low genetic correlations between them, the only exception being that between FCS and DS (0.63). Most genetic correlations varied little over the age range with the exception of FEC and BW, which fell from 0 at weaning to −0.63 at hogget age. Whereas FCS and DS may be good indicators of scouring, they are very different from FEC as an indicator of host resistance to gastrointestinal parasites.

Data from 3 rabbit breeds, namely New Zealand White (N), Californian (C), and Flemish Giant (F), and their crosses, i.e. CN, FN, F(CN), and C(FN), were analysed for individual growth traits such as body weights at 5 (5WT), 6 (6WT), 7 (7WT), 8 (8WT), 9 (9WT), and 10 (10WT) weeks of age, and post-weaning average daily gain between 5 and 10 weeks of age (ADG), and individual slaughter traits such as liveweight at slaughter (SW), carcass weight (CW), and dressing percentage (DP). Data included records for individual body weights from 1345 to 1524 rabbits from 279 litters and records for slaughter traits from 919 rabbits from 245 litters. Significant sources of variation for individual growth and slaughter traits were breed, parity, month-year of birth, sex, and number weaned per litter (NW). However, parity and NW did not significantly affect ADG and DP. Slaughter traits were not significantly affected by sex. The overall least squares means for 5WT, 6WT, 7WT, 8WT, 9WT, 10WT, ADG, SW, CW, and DP were 836 g, 1021 g, 1215 g, 1390 g, 1577 g, 1791 g, 27.2 g/day, 2.28 kg, 1.23 kg, and 53% respectively. N and F purebred, and FN crossbred rabbits performed significantly (P < 0.05) better than C purebred and crossbreds [CN and C(FN)] in all the individual growth and slaughter traits except for DP. CN performed better (P<0.05) in DP than all other crosses. ADG of C rabbits was significantly (P < 0.05) lower than of all other crosses under study, with F(CN), C(FN), and CN crosses showing intermediate growth rates. Significantly (P < 0.05) higher growth rates were observed in N, F, and FN breeds. There was no significant heterosis observed in the breed crosses for any traits under study. Individual body weights at 5–10 weeks of age were significantly lower in the 1st parity born rabbits than in other higher parity born rabbits. SW and CW were significantly higher in 2nd and 3rd parity rabbits than in 1st and 4th and later parity born rabbits. Female rabbits achieved heavier weights at 5, 6, and 7 weeks of age than males and males weighed more than females after 7 weeks of age. ADG of males was significantly (P<0.05) higher than of females. Significant negative regression coefficients of NW on all individual body weights until slaughter age showed that larger litters had lighter rabbits. Coefficient of variation for individual growth and slaughter traits ranged between 11.1 and 20.7%. Common litter variance explained a significantly large proportion of total phenotypic variance, with the proportions ranging between 0.36 and 0.55 for individual growth traits, 0.46 for SW, and 0.35 for CW.

Data from a rabbit breeding experiment were analysed to compare the doe reproductive and pre-weaning litter performance of 3 breeds of rabbits, namely New Zealand White (N), Californian (C), and Flemish Giant (F), and their crosses CN (C × N) and FN (F × N). The foundation stock of 152 rabbits was collected from 26 different sources in New South Wales, Australia. Data on reproductive traits, doe age at first successful mating (DA), doe weight at first successful mating (DW) arising from 104 does, conception rate (CR) from 808 matings, and kindling interval (KI) from 325 records of 119 does were analysed. Overall means for reproductive traits DA, DW, CR, and KI were 21 weeks, 3.6 kg, 0.75, and 7.4 weeks, respectively. DA, CR, and KI did not differ significantly among different breeds and their crosses. DW of C does was found to be significantly lighter than all other breed crosses in the study. Month –year of mating significantly affected DA, DW, and CR (P < 0.01), and as the parity number increased, there was a significant (P < 0.01) decrease in KI. As age of the doe at mating increased there was a significant increase in DW (P < 0.01), CR (P < 0.05), and KI (P < 0.01). Data from 436 litters of 157 does were included in the analysis of pre-weaning litter traits. The overall means for the pre-weaning litter traits were: number born per litter (NB, 8.1), number born alive per litter (NBA, 6.9), number weaned per litter (NW, 3.3), total litter birth weight (TLBW, 453.7 g), live litter birth weight (LLBW, 397.1 g), litter weaning weight (LWW, 2.8 kg), and average birth weight of kits per litter (ABW, 58.1 g). Doe breed significantly affected NW (P < 0.05), TLBW (P <0.01), LLBW (P < 0.05), LWW, and ABW (P < 0.01). N does and crossbred does (CN and FN) performed better than purebred F and C does for NW and LWW. A significant heterosis of 41.9% and 40.8% was observed in CN does for traits NW and LWW, respectively. ABW of F does was significantly higher than that of all other breed crosses in the study. Buck breed did not have any significant effect on any of the pre-weaning litter traits under study. Parity significantly affected NW (P < 0.05), TLBW (P < 0.01), LLBW (P < 0.05), and ABW (P < 0.01). First parity does produced litters with significantly lighter birth weights. The month–year of birth effect was significant for NW, LWW (P < 0.01), and ABW (P < 0.05).The coefficients of variation for the doe reproductive traits and pre-weaning litter traits ranged between 12.1 and 59.5% and 16.1 and 93.3%, respectively. High phenotypic variances and coefficients of variation observed for traits NW and LWW indicate that good response could be realised through selection. Repeatability estimates for reproductive traits CR and KI were very low. Low to moderate repeatability estimates in the range 0.17–0.25 were observed for pre-weaning litter traits. Significant positive phenotypic correlations were observed between litter size and litter weight traits (0.30–0.97). A significant negative correlation was observed between ABW and NB (–0.56) and NBA (–0.36).

An in vitromodel of vascular damage was used to investigate the ability of seeded endothelial cells to resist shear stresses generated in a perfusion circuit. At perfusion rates of 100 ml/min the maximum shear stress reached 16.5 dyn/cm2. At this level the rate of cell detachment from the damaged vascular surface was 88 per cent per h for the first 20 min of flow but gradually decreased to 5 per cent per h after 90 min. These findings suggest that endothelial cells may be retained on damaged vascular surfaces in conditions that approximate to arterial flow.

An in vitro model to facilitate the study of endothelial cell seeding of damaged vascular surfaces has been developed. This may have applications in the study of endothelial seeding of angioplasty and endarterectomy sites. Using this model, the optimum endothelial seeding time for attachment to damaged vascular surfaces should not exceed 30 min and, to achieve confluent cell attachment, a seeding density >5 × 105cells/cm2should be used.

High-field 1H-n.m.r.-spectroscopic studies supported by chemical carbohydrate analyses show that skeletal keratan sulphates (KS-II) of bovine origin may be sub-classified into two groups. Keratan sulphate chains from articular and intervertebral-disc cartilage (KS-II-A) contain two structural features, namely alpha(1----3)-fucose and alpha(2----6)-linked N-acetyl-neuraminic acid residues, that are absent from keratan sulphates from tracheal or nasal-septum cartilage (KS-II-B).

Merino sheep representing a range of bloodlines in resource flocks located across Australia were tested for resistance to gastro-intestinal nematodes. These flocks included the JB Pye Flock (Camden, NSW), Katanning Base Flock (Katanning, WA), Turretfield Merino Resource Flock (Rosedale, SA), and the CSIRO Finewool Flock (Armidale, NSW) and included a total of 328 sire groups. Resistance to nematodes was measured by faecal egg count (FEC). Data were also available for greasy and clean fleece weight (GFW and CFW, respectively), fibre diameter (FD), and body weight (BW) at a range of ages from weaning to 21 months. Variance components were estimated by restricted maximum likelihood, fitting an animal model and estimating covariances in a series of bivariate analyses. Phenotypic correlations between FEC0·33 and production traits were all close to zero ( –0·09–0·02). Genetic correlations between FEC0·33 and production traits were –0·20, –0·18, and –0·26 for weaning weight, 10-month BW, and 16-month BW, respectively; 0·21, –0·06, and 0·21 for 10-month GFW, 16-month GFW, and 21-month GFW; 0·21, –0·05, and 0·07 for 10-month CFW, 16-month CFW, and 21-month CFW; and –0·09, –0·12, and 0·04 for 10-month FD, 16-month FD, and 21-month FD. When estimates were pooled for all fleece traits and all BW traits, the genetic correlations between FEC0·33 and GFW, CFW, FD, and BW were 0·15, 0·10, –0·06, and –0·21, respectively. Using pooled estimates for CFW, FD, and BW, selection for a breeding objective based on production traits alone would lead to an unfavourable correlated response in FEC0·33 of approximately 1% per year. genetic covariance, faecal egg count, host resistance, correlated response.

Chemicals that interfere with the formation of tannin-protein complexes were evaluated as dietary additives for mulga-fed sheep in pens and under paddock conditions. Condensed tannins (CT) in mulga inhibit protein digestion, and the use of chemicals to precipitate CT or dissociate CT-protein complexes may improve production from sheep consuming a mulga diet. In a digestion study with mulga-fed sheep in pens, provision of polyethylene glycol (PEG) at a rate of 6 g/day significantly (P &lt; 0·05) improved nitrogen (N), phosphorus (P), and sulfur (S) balance, and apparent N, P, dry matter (DM), and organic matter digestibility, and the rate of liveweight gain. Addition of the surfactants SDS or alkanate 3SL3 to the diet of mulga-fed sheep did not improve N balance or digestion; however, apparent digestibility of P, and P and S balance, were significantly improved by SDS. Teric PE64, a compound structurally similar to PEG, significantly improved S balance, but not DM intake or N balance. For sheep consuming a predominantly mulga diet under paddock conditions, provision of PEG at a rate of 12 g/day significantly improved clean wool growth and liveweight gain compared with unsupplemented sheep, by 9% and 100%, respectively (0·809 v. 0·745 mg/cm2.day, and 44 v. 22 g/day). The studies demonstrated that although surfactants can affect mulga digestion, using PEG to precipitate CT is more effective to improve mulga digestion and animal production than the use of surfactants. However, the wool and liveweight production responses achieved with PEG were not sufficient to justify its wide-scale use for mulga-fed sheep. Consequently, alternative methods should be sought to reduce the negative effects of mulga CT on sheep production. Additional keywords:wool, protein, condensed tannin.

Colditz I. G., Watson D. L., Gray G. D. & Eady S. J. 1996. Some relationships between age, immune responsiveness and resistance to parasites in ruminants. International Journal for Parasitology 26: 869–877. In the Australian livestock industries, susceptibility to infectious diseases is generally greater in young than in mature ruminants. The increased susceptibility is manifest as respiratory and intestinal infections (viral and bacterial) of calves, as well as fleece rot, flystrike and, especially, gastrointestinal parasitic infestations of young sheep. Lower resistance to infectious disease in young ruminants appears to be due largely to immunological hyporesponsiveness, and is not simply a consequence of their not having been exposed sufficiently to pathogens to develop active immunity. Young sheep have significantly lower proportions of CD4+ and CD8+ lymphocytes, but similar proportions of T19+ and B lymphocytes in blood, lymph and skin compared with mature sheep. Blood lymphocytes from young sheep produce less interferondashγ in culture and young sheep invariably mount smaller antibody responses than do mature animals. Taken together, these findings begin to explain why young ruminants are more susceptible to infectious diseases in general, and to gastrointestinal parasites in particular, when compared to mature animals. Haematological markers of disease resistance, the prevalence of nondashselected diseases and immune responses to vaccination were examined in the internal parasite-resistance flocks in Armidale NSW and the fleece rot/flystrike selection flocks at Trangie NSW. Any programme that seeks to improve resistance to parasitic or any other disease should have the capacity to make contemporary measurements of resistance to other diseases which are important in, or threaten, the production system.