Eating Quality R&D
|Project start date:||01 July 2013|
|Project end date:||30 June 2014|
|Publication date:||23 November 2018|
|Livestock species:||Grassfed cattle|
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Pasture-based beef production in Southern Australia is constrained by seasonal variation in pasture growth and availability, with abundant growth in spring but significant feed deficits during autumn and early winter. The minimal pasture growth of conventional dryland pasture systems during this time have proved unsuitable for finishing of cattle in autumn and winter, leading to low growth rates and poor Meat Standards Australia Australia (MSA) compliance due to high pH and dark meat colour. As a result, producers are unable to consign cattle for slaughter consistently during this time. The seasonal nature of supply is a major constraint for the development of specific 'pasture-finished' branded product lines. Therefore, there is significant need for alternative grazing systems which can aid in addressing the supply and MSA compliance challenges during these seasons.
The use of irrigated forages to fill seasonal pasture supply shortages is commonplace throughout the Limestone coast region of South Australia. There is a myriad of options available, from perennial pastures through to annual pastures, forages and crops. Fodder beet (Beta vulgaris) is a new option to Australian producers and is a very strong candidate to complement existing grazing systems by effectively filling autumn/winter feed gaps. Fodder beet is characterised by very high dry matter production, high energy content and relatively low cost of production per unit of metabolizable energy. Grazing of fodder beet in situ has revolutionised the New Zealand beef industry by allowing cost effective accelerated weight gain during winter. The soil types and summer climate within the Limestone Coast are suitable for fodder beet production. This is predicted to be associated with higher cattle weight gain during autumn and winter, increased supply of (pasture certified) finished stock in autumn and winter with higher carcass merit (MSA Index, MSA marbling) and increased MSA compliance.
This project sought to implement and evaluate the role of fodder beet in commercial beef production systems throughout the Limestone Coast region of South Australia. Six commercial sites were established across two seasons (2016-17) to characterise the agronomic needs of fodder beet, potential animal performance and economics in the farm system. Fodder beet crops were sown in Spring (October-November) of 2015 and 2016 for grazing in the autumn of 2016 and 2017 respectively using agronomic programs adapted from New Zealand. Yearling British breed steers averaging 340kg were stocked at 10 head/ha (approximately 120 dry sheep equivalents) onto the crops and transitioned onto an ad libitum diet of fodder beet over a 21 day period. Once at ad libitum intake, steers were strip grazed into the crop and provided ad libitum access to low quality cereal straw or pasture hay. An equal number of steers of the same genetic background were managed under each participating properties normal business practice for comparison as a control. Steers were weighed at 4-6 week intervals throughout the grazing period and slaughtered once they had reached 600-640 kg live weight. Carcasses were graded to Meat Standards Australia Australia specifications at Teys Australia abattoir, Naracoorte, South Australia. Both fodder beet crops and control pastures and forages were sampled regularly for quality, yield and utilisation during the grazing period.
Fodder beet crops used an average of 6.02 ML/ha of water to grow 25,583 kg of dry matter per hectare (4250 kg/ML water). Feed quality was exemplary, with 11% dry matter, 11.2 MJ ME/kg DM and 12.6% CP for the whole crop. Total establishment cost averaged $3049/ha, which equates to 12c/kg DM. An average utilisation of 89% was able to be achieved by strip grazing animals, which means the actual cost of feed consumed was 13.3c/kg DM.
Across the 6 sites the average daily gain of cattle whilst grazing fodder beet was 0.92kg/d, which was significantly higher than the average of 0.76kg/d across control sites during this same period. However, control animals accelerated their weight gain in spring and increased their overall average daily gain to 0.96kg/day. A number of issues were encountered across the sites, mainly around managing consumption of the leaf component of the beets and managing the consistency of intake. As a result the per hectare liveweight gain of fodder beet systems ranged from 856-1875kg/ha, which resulted in a range in cost of production from $1.87-4.24/kg liveweight gain. Consequently, gross margin figures ranged from -$1233 to +$2681/ha. These results show the production potential of fodder beet grazing systems, but highlight the importance of crop yield and the efficiency of utilisation by the animals grazing it to maximise liveweight gain and thus gross margin.
The carcase quality of steers slaughtered directly off fodder beet was acceptable, with a proportion of animals able to be slaughtered earlier in the year due to the maintenance of higher growth rates during autumn and winter. Once adjusted for carcase weight, fodder beet steers had significantly lower rib fat depth than control grazed animals (5.7 vs. 7.9 mm) and lower ossification score (134 vs. 144), yet higher eye muscle area (72.5 vs. 72.3 cm2) and MSA marble score (395 vs 387). One consignment of fodder beet grazed steers had encountered some nutritional perturbation and as a result had variable and lower growth rate. As a result there were some animals that had high ultimate carcase pH, and were non-compliant to MSA specifications. All other animals slaughtered off fodder beet were compliant to MSA specification. 92.5% of the control animals were compliant to MSA specifications.
The ability for fodder beet to provide such high yields of a high quality (11 MJ ME/kg DM, 12-13% CP) standing feed source from late summer through winter make it an incredibly attractive option for filling the autumn-winter feed gap in south eastern Australia. There is considerable scope to increase weight-for-age in pasture-based finishing systems and shorten time to slaughter, enabling producers the opportunity to access seasonal price premiums. For fodder beet systems to be economical, crop yields need to be maximised through site preparation and weed control, and animal performance must be optimised. There are however, a number of factors pertaining to the composition of fodder beet intake and mineral nutrition that need further investigation to optimise animal performance and enable producers to implement this grazing system with confidence.
|Project manager:||Alex Ball|
|Primary researcher:||The University of Adelaide|