Yaks have evolved special adaptations to withstand the severe cold, hypoxia, strong UV radiation, and deficiencies in nutrient intake. Our study was conducted to characterize N use efficiency in growing yaks. We found as much as 87% of the urea synthesised in the liver was returned to the gastrointestinal tract when the yaks were fed a diet with maintenance N level. Moreover, constantly greater amounts of the urea production than the digestible N intake, and the gastrointestinal urea clearance than the kidney urea clearance were observed respectively in the growing yaks regardless of the N intakes. These results suggest that yaks might be more efficient at utilising N under harsh environment compared to cattle.

Cattle fed grain diets can develop an acidosis with decreased efficiency in starch utilisation, resulting from the rapid production and accumulation of lactic acid in the rumen. The use of the bacteria Megasphaera elsdenii and Ruminococcus bromii as probiotics to alleviate acidosis and improve animal performance was investigated. A feedlot trial was undertaken and steers were orally drenched with these bacteria. Steers were fed for 70 days with a commercial feedlot ration. High growth rates were achieved and steers acquired dense populations of M. elsdenii. However, R. bromii was only transiently dominant. Between 14 and 28 days, bacteria related to Ruminobacter spp. became dominant and may be of future interest in the development of probiotics for grain-fed cattle.

It is very important to understand the correlation between muscle-fibre types and pork quality for improving pork quality. We investigated the myosin heavy chain (MyHC) mRNA composition, and found that muscle-fibre types of longissimus muscle were influenced by pig genotypes, and closely related to energy metabolism status. The results provide some evidence for exploring the effective mechanism of muscle-fibre types on pork quality.

The recovery and use of haemoglobin (usually wasted) from slaughterhouses to produce peptides destined for animal feeding is a good way to reduce the pollutant charge of animal blood. In the present work, an easy to control and cheap method was developed to transform haemoglobin into profitable peptides and amino acids. The process involved in this transformation has been carefully studied and characterised. The results show that it is possible to process great amounts of protein using a common reaction, to produce a high quality product.

Genetic parameter estimates for growth traits of Gansu Alpine Finewool sheep that separately identify maternal effects have not previously been conducted. This paper reports the results of a study of more than 17000 lambs from the Gansu Sheep Breeding Technology Station in north-western China. The study provides the breed and its associated industry with a more encompassing basis for the design and implementation of genetic improvement programs.

New prediction equations for mortality and conception rates for beef breeding cattle were estimated, based on the analyses of comprehensive data sets across northern Australia. These improved dynamic equations agree with further independent data sets, and conform to expert opinion, so can now be used in simulation models and investigations of beef breeding enterprises in northern Australia.

Feed digestibility is commonly assessed in situ, with nylon bags placed into the rumen of cows, or in vitro, using rumen fluid collected from surgically cannulated cows. In this experiment, use of rumen fluid collected by suction from intact donor cows produced in vitro feed digestibility values strongly correlated and directly proportional to those obtained in situ. The use of cannulated cows can be avoided.

External parasites are a likely cause for fine pitting damage, a defect that decreases the value of ostrich leather. Infestation with ostrich feather lice was hypothesised to cause pitting, but was found not to be related to pitting damage, nor growth or productivity, even though it decreases feather quality. The root cause of pitting damage on ostrich skins remains unclear, and further research is needed to curb monetary losses.

Four prediction equations of scanned P8 fat (mm) before slaughter and 4 carcass intramuscular fat (i.e. marbling) equations, across 4 years (1995 to 1998), were developed. The forage crop growth pathway tended to influence both scanned P8 fat (mm) before slaughter and carcass intramuscular fat more so than any other pathway. These results have the potential to assist the beef industry meet market specifications.

Toxicity in ruminants grazing leucaena was first studied in detail in the 1970s and 80s leading to the discovery that inoculation with the rumen bacteria Synergistes jonesii successfully protected animals from toxicity. However, a survey of cattle grazing leucaena in Queensland, thought to be protected, showed that 48% of 44 herds studied had high levels of DHP in urine indicating possible subclinical DHP toxicity. Since reduced productivity negates the key advantage of leucaena pastures, further research and education is warranted to ensure that the full benefits of leucaena pastures are realised.

There is little loss of hybrid vigour from use of composite breed dams. Poorer lamb growth over summer months in intensive lamb production systems needs to be addressed by management. Using cryptorchid lambs among early drop singles in good growing seasons allows earlier turnoff of heavier and leaner lambs than wethers and can reduce remaining stocking pressure.