The nutritional value of two recently developed New Zealand cultivars of triticale, 'Aranui' and 'Karere', was determined by chemical analysis of the grain and by animal feeding studies. Four trials were carried out using rats to determine protein quality, apparent digestibility of protein and amino acids, apparent digestible energy (ADE) and apparent metabolisable energy (AME), and the capacity of triticale to support growth of rats followed by postmortem examination of the carcasses. Pigs were used to determine ADE and AME, and cockerels were used to determine true metabolisable energy (TME). Protein quality, as assessed by amino acid analysis (i.e., amino acid score) and determined by the rat bioassay procedure of relative protein value (RPV), was not different between cultivars. Rat ileal apparent digestibilities of amino acids were also not different between cultivars except for methionine and arginine. The ADE and AME bioassays using the rat and pig, and the TME bioassay using the cockerel, all showed a higher content of DE and ME in 'Karere'. 'Aranui' and 'Karere' supported similar rates of liveweight gain of rats given diets containing the same levels of crude protein. Postmortem examination of the carcasses showed no gross differences in the appearance of tissues and organs of rats fed triticale and control (lactalbumin) diets. The crude protein content of the two samples of triticale used in the evaluation was higher in 'Karere'. Five additional pairs of triticale samples from other localities showed a consistently higher level of crude protein in 'Karere'. From a nutritional standpoint, 'Karere' was the preferred cultivar because of a higher crude protein, DE, and ME content. The nutritional parameters determined with triticale were compared with corresponding literature or measured values for barley and bread wheat.

Groups of sheep were fed either fresh ryegrass pasture, a low condensed tannin (CT) diet (Lotus corniculatus; or a medium CT diet (L. pedunculatus) to compare the effects of these feeds on methionine and cysteine metabolism, because of their significance in wool production, and on phenylalanine as an indicator of general protein metabolism. Dry matter intake (DMI) among groups, ryegrass pasture, Lotus corniculatus, L. pedunculatus, were significantly different, therefore the treatment means for metabolic measurements and wool growth were adjusted by covariate analysis using DMI. Neither diet nor DM1 had any overall effect on phenylalanine concentrations in whole blood or phenylalanine irrevirible loss rate (IRL). However there were significant (P < 0.001) diet effects on cysteine blood concentrations. Methionine effects paralleled those of cysteine, with higher concentrations in sheep fed L. pedunculatus relative to pasture fed animals. Sheep fed L. pedunculatus had much higher cysteine and methionine ILRs compared with either the pasture or L. corniculatus groups. Sheep fed the highest level of condensed tannin in their diet (l. pedunculatus) had significantly greater rates of transsulfuration, cysteine and methionine oxidation. Overall the results show that CT in L. pedunculatus gives a greater degree of 'protection' during digestion for cysteine, methionine and phenylalanine, while L. corniculatus resulted in very little advantage. Condensed tannin effects on wool production are marginal and secondary to whole body metabolic influences.

Romney wether sheep were given ZnO on a regular basis, as required in protocols for the treatment of facial eczema, at either 12 g ZnO fortnight-1 or 12 g ZnO week-1, and the effect of Zn on the synthesis of different metallothionein (MT) isoforms isolated from liver tissue characterized and quantified. Metallothionein isoforms in liver of dosed and non-dosed sheep were quantitatively determined by reverse phase HPLC, with markedly increased concentrations of total MT-Ia protein found in the liver tissue of Zn-dosed groups (634 pg g-l fresh weight for the weekly dosed group) compared with 49 pg g-1 fresh weight in non-dosed sheep. The concentration of MT-II protein was not significantly increased. Individual sheep varied widely in the relative amounts of each MT isoform expressed with increased amounts of types of MT-Ia especially, and MT-I1 in some animals, which bound predominantly Cu. The half-lives for [35S]-cysteine and 67Zn in MT isoforms from weekly dosed sheep were found to be 2.5-3.5 days and 5-24 h respectively, indicating relatively fast exchange of Zn with MT compared with synthesis. Rate of synthesis for MT-Ia was twice that for MT-11. Data reflecting relationships between MT isoforms, Cu and Zn concentrations in liver are presented and discussed.

Six lactating ewes were orally drenched each day with polyethylene glycol to remove the effects of the condensed tannins in sulla (Hedysarum coronarium) and six other ewes (control) received a drench of water. The treatments were started 28 days prior to the measurement period. At week 6 of lactation, net absorption of branched-chain amino acids in the mesenteric vein was not affected by PEG. Valine and leucine were released by the liver in the PEG ewes and extracted in the control ewes. The net mammary uptake of isoleucine and leucine was lower in the PEG ewes.