The literature pertaining to the effect of forage-and grain-based feeding systems on beef quality has been reviewed in light of considerable interest in New Zealand regarding the relative merits of grain-and grass-based beef finishing systems. In particular, fifteen experiments which compared forage-and grain-finished beef at the same carcass weight or degree of fatness, have been selected from the literature. When compared at similar carcass weights or the same degree of fatness, the type of feeding system had no effect per se on tenderness, juiciness, lean meat colour, marbling, or pH. In eight out of twelve experiments where flavour was assessed, panellists could not distinguish an effect of diet on flavour. Effects on fat colour were variable and, in six of the nine experiments where fat colour was measured, grain feeding failed to "improve" fat colour. It is concluded that there is little scientific justification for the claim that grain feeding is necessary to produce high quality beef. Beef of comparable quality can be obtained from cattle finished on forage-based diets (i.e., pasture) provided that acceptable carcass weights and degrees of finish can be achieved at a young age.

An experiment was carried out to compare the quality of beef produced from Hereford (H), Hereford × Friesian (HF), and Friesian (F) steers grazed together on pasture from weaning. Carcass characteristics, meat quality parameters, and consumer acceptability were compared when the breeds were slaughtered at the same age (H, HF1, Fl) and at the same level of "fatness" (i.e., same biological maturity; H, HF2, F2). H steers reached slaughter weight and fatness at 27 months of age (approx. 610 kg, 6.75 mm fat at 12th rib, respectively) at which time all H, half the Hereford × Friesians (HF1), and half the Friesians (Fl) were slaughtered. The remaining steers (HF2 and F2) continued to graze until they reached a similar level of fatness to H steers and were slaughtered at 29 and 35 months of age, respectively. Growth rates were similar between breeds throughout the trial.

~~~Twelve lambs, paired on the basis of live weight, were cannulated in the abomasum, in the proximal jejunum approximately 4 m distal to the pylorus and in the terminal ileum. Six were infected with 3000 Trichostrongylus colubvifovmis and 3000 Ostevtagia civcumcincta larvae each day for 18 weeks and the remainder were pair-fed to individual infected lambs. All animals were offered ryegrass (Lolium perennebwhite clover (Tvifolium vepens) pasture, cut daily. Dry matter (DM) intake, live weight, faecal egg concentration, plasma pepsinogen and plasma protein concentrations were measured weekly. During weeks 7 and 17 after commencement of infection, the flow of digesta along the gastrointestinal tract was measured together with enteric plasma loss and true digestion and absorption of 1*51-labelled albumin in the small intestine. DM intake was depressed by parasitism, being 1331, (SE 70), 423 (SE 32) and 529 (SE 52) g/d during weeks 3, 7 and 17 respectively. The flow of nitrogen at the proximal jejunum and in faeces was increased by parasitism during week 7 and at the abomasum and ileum during week 17. Plasma protein-N loss (g/d) into the gastrointestinal tract was 0.68 (SE 0.091) and 1.97 (SE 0.139) during week 7, and 0.85 (SE 0.158) and 1.96 (SE 0.396) during week 17, in control and infected sheep respectively. True digestion and absorption of albumin in the proximal small intestine, the site of infection, was very low (mean 0 0 8 ) and was not affected by parasitism. Between the abomasum and terminal ileum absorption of albumin was high (mean 0.87) and again was not affected by parasitism. It was calculated that of the total increase in endogenous protein passing from the ileum tract as a result of infection, plasma protein comprised only a small percentage (10-36%). The major proportion of digestion and absorption of protein occurred in the distal small intestine beyond the site of infection and was not affected by infection. The sites of predilection of Ostertugiu circumcincta and Trichostrongylus colubrijormis in sheep are the abomasum and anterior small intestine respectively. The implications of pathological damage for protein digestion and subsequent absorption have not been established, partly because of uncertainty about the role of the abomasum and proximal small intestine in protein digestion and absorption, even in uninfected animals.Studies of the peptidase activity of the gastrointestinal tract have shown values at the site of infection in the small intestine of only 17% of those in distal parts of the intestine (Richardson &Jouan, 1986), andJones (1982) showed no effect of infection with T. vitrinus on these activities. Infection with T. colubriforrnis is, however, associated with increased digesta nitrogen flow past the ileum (Poppi et al.

No abstract

A study was undertaken to evaluate the relative importance of milk and pasture to lamb growth during lactation under a high performance lamb production system. A total of 285 East Friesian x Romney (EFxR), Finn x Romney (FxR) and Romney (R) maiden 2-tooth ewes lambed following insemination with semen from six high growth rate Poll Dorset and composite rams. Mean lambing date was 16 July 1998. Breed groups were run together in either single or twin mobs and fed at high levels of nutrition (pasture covers were maintained at 1400 kg DM/ha or greater throughout lactation). Average lamb growth rates from birth to 15 weeks of age were 343 g/d and 292 g/d for single and twin lambs, respectively. Single and twin lambs reared by EFxR ewes grew significantly faster than lambs reared by the other ewe breeds. Ewes were milked at 3-weekly intervals using oxytocin with EFxR ewes producing significantly more milk than the other breeds throughout lactation. Milk composition varied significantly between ewe breeds with FxR ewes producing significantly higher fat % and total milk solids (P

There is evidence that, in cattle, rapid compensatory growth after a period of growth restriction may increase the variability of beef quality and that variability is greater in breeds which reach larger body size at maturity. This experiment investigated the effect of compensatory growth following a period of winter growth restriction on carcass quality in steers of small and large mature size grazed on pasture. Angus (no. = 120) and South Devon ✕ Angus (SD✕ A; no. = 110) steers were allocated to non-restricted or restricted growth treatment groups and for 126 days over winter their grazing was managed to achieve mean live-weight gains of approximately 0·7 kg/day or to maintain live weight for each group respectively. Steers were slaughtered at the start (no. = 10 per breed) and end (no. = 20 per nutrition group (10 from each breed)) of the winter period for carcass evaluation. Thereafter, remaining steers were grazed together at a high pasture allowance to maximize growth and were slaughtered for carcass evaluation as they reached target live weights (Angus, 590 kg; SD✕ A, 620 kg). SD✕ A steers grew faster ( P < 0·05) during both the winter and finishing periods and reached target slaughter live weights approximately 20 days earlier than Angus steers. SD✕ A steers also had leaner carcasses than Angus steers at each slaughter although there was no significant difference in meat quality between breeds. However, there was a significant effect of restriction treatment on carcass weight and meat quality. The non-restricted steers grew faster, had heavier carcasses and more tender steaks than restricted steers, although there was no significant difference in carcass fatness (adjusted for hot carcass weight). Muscle calpain activities were positively correlated with live-weight gain during the finishing period suggesting increased potential for post-mortem myofibrillar proteolysis and therefore increased meat tenderness. However, in the present experiment this was confounded by an increase in shear force with age-at-slaughter, especially in the non-restricted steers. Nevertheless, steers which were heaviest at the start of the experiment reached slaughter live weight earliest, were leaner than average and had higher calpain system activities at slaughter regardless of breed or restriction treatment. Furthermore, in the non-restricted group, high initial live weight and early slaughter was associated with lower pH and more tender meat. In conclusion, although restriction affected meat quality attributes, it appears that live weight prior to food restriction also had a considerable effect on carcass characteristics at slaughter. Therefore, the characteristics of the early growth phase prior to the finishing period may have important consequences for meat quality.

Hereford × Friesian beef cows were managed on one of five lifetime liveweight profiles with the relative differences maintained throughout the 4-year period of the project. The objective was to determine optimum beef-cow liveweight profiles for use by farmers. In the first year, 115 in-calf heifers entered the trial in January 1991 at age 18 months. This process was repeated annually to replace culled and empty cows so that in the second, third, and fourth years there were 139, 152, and 144 cows, respectively, on the trial with 4 age classes on the trial in the fourth year. Four times each year (pre-calving, early lactation, mid lactation, and post weaning) dry matter intake by the cows was estimated using slow release chromic oxide capsules, faecal grab sampling, and estimates of in vitro digestibility of pasture samples. The cows and their calves were weighed every 4 to 6 weeks, and the calves were weaned at about 180 days when they left the trial. During most of the trial, mean cow liveweight spanned a range from 350 to 500 kg. The profiles were significantly different, as were their effects on cow condition score, cow pasture intake, calf liveweights, and, sometimes, cow reproduction. For every kg extra that the cows were heavier, dry matter intake increased by 15 to 60 g d ' depending on physiological status. When cow mating weight was fitted in regressions against cow reproductive items, optimum cow liveweight was A98057 estimated to be 440 kg with very little change in output over the range 420 to 450 kg liveweight. Calf growth rate showed a linear response of 1.2 g additional daily gain per kg increase in cow mating weight. Over 180 days from birth to weaning, this amounted to 0.22 kg extra calf weaning weight per kg of cow mating weight.

Absorption of albumin across the whole small intestine was high (0.87) and occurred mostly distal to the site of intestinal parasitism in both parasitized and control animals. This helps to explain why intestinal parasitism has no effect on protein absorption from the small intestine.Key words: Sheep, nematode, plasma loss, albumin absorption [197][198] (Sept. 1984) labelled albumin/5rCIEDTA in digesta collected from the two intestinal cannulae after injection into the abomasum at 6 and 17 wk.