The effect of ingesting a saltbush and barley ration on the carcass and eating quality of sheepmeat

Abstract

Forage halophytes such as saltbush (Atriplex spp.) are widely used to revegetate Australian saline land and can provide a medium-quality fodder source. An animal house experiment was conducted to investigate differences in the carcass and eating quality of sheep ingesting saltbush from saline land in combination with a barley supplement. Twenty-six merino hoggets (two groups of 13) were fed either a 60 : 40 dried saltbush (Atriplex nummularia): barley (S 1 B) ration or a 33 : 25 : 42 lupins : barley : oaten hay ration (C) for 10 weeks prior to commercial slaughter. After 10 weeks, all sheep were commercially slaughtered and a single loin (from 12th rib to chump) collected from each animal for taste-panel analysis. Carcass weight, total tissue depth over the 12th rib 110 mm from the midline (GR fat depth), ultimate pH and colour were determined and X-ray bone densitometry used to estimate the fat content of the carcass. Blood samples were taken to assess the hormonal response to ingesting these diets and fatty acid profiles of the subcutaneous and intramuscular fat were determined. Both groups grew at the same rate (62 g/day) and had similar hot carcass weights (P . 0.01) (17.2 6 0.3 kg for S 1 B and 17.9 6 0.3 kg for C). However, these live weights may not be high enough to be commercially viable such that saltbush and barley may only be suitable as a maintenance feed. The S 1 B-fed sheep had a significantly (P 5 0.055) lower fat and higher lean content (P , 0.05) than the C group. This is a positive finding as fat denudation is a significant cost to processors and farmers can produce sheep that are depositing less fat or more lean per unit of live-weight gain. The decreased fat and increased lean content were attributed to the higher protein : energy ratio available for production and lower circulating insulin and higher growth hormone of the S 1 B-fed sheep. The lower body-fat content and lower metabolisable energy and digestible organic matter intake did correlate with the sheep fed the S 1 B diet, having a significantly lower percentage of unsaturated fat and equal levels of saturated fat than the C treatment. Diet had no effect on the ultimate pH or colour of the meat. Treatment had no significant effect on any of the eating-quality attributes (P . 0.1). The drying of the saltbush, the shorter length of the experimental period and the low carcass fat content were believed to have contributed to this result. Further field experiments are needed to clarify the benefits to carcass and eating quality of ingesting saltbush.

Salt intake and reproductive function in sheep

“…The sheep fed saltbush and barley supplement could then have a decreased energy availability, which in addition to the higher energy requirements to process salt (Arieli et al, 1989) would decrease the availability of energy for lipogensis. Sheep fed saltbush and barley supplement have also a higher proportion of lean meat compared to controls (Pearce et al, 2008). Lean muscle deposition is driven by a higher protein-to-energy ratio available in the diet (Searle et al, 1982;Campbell et al, 1984;Campbell, 1988), so, as described above, the increased rate of passage and protein available in response to salt intake could explain the associated increase in lean meat (Hemsley et al, 1975).…”

“…Lean muscle deposition is driven by a higher protein-to-energy ratio available in the diet (Searle et al, 1982;Campbell et al, 1984;Campbell, 1988), so, as described above, the increased rate of passage and protein available in response to salt intake could explain the associated increase in lean meat (Hemsley et al, 1975). It has to be noted that the pH or the color of meat or any eating quality attributes were not modified by feeding saltbush and barley supplement (Pearce et al, 2008). Figure 1 The renin-angiotensin system is responsible for the maintenance of salt and water balance.…”

“…The ingestion of a high-salt load from the consumption of halophytes, saltbush and barley supplement or saline water reduces the fat content of the carcass (Walker et al, 1971;Kraidees et al, 1998;Pearce et al, 2008). This decrease in fatness can be explained by the reduced fermentation of organic matter in the rumen and lower absorption of volatile fatty acids associated with the consumption of a high-salt diet (Hemsley et al, 1975).…”

Sustainable Agriculture in the Arabian/Persian Gulf Region Utilizing Marginal Water Resources: Making the Best of a Bad Situation

“…Therefore, these dicots can be included as a significant component of a total mixed ration to provide energy and a nitrogen source for protein production. It has recently been shown that halophytes can be included as a significant component of a feedlot diet in a series of experiments investigating how consumption of halophytes influences meat eating quality [49,50,62,63]. Sheep that were fed diets that contained a high proportion of halophytes exhibited moderate weight gain and produced meat with a high eating quality (determined by a taste panel) and the meat also had extended shelf life.…”

<b>Levels of concentrate and sources of non-fiber carbohydrates on productive performance and ruminal kinetics of finishing cattle</b>

“…According to Pearce, Pethick and Masters (2008), increased propionate production stimulates insulin concentration, which is the hormone regulating the fat deposition in the carcass. However, in the present study, the SFC only increased fat thickness, with no effects on ADG or G:F ratio.…”