Farm Table says:
What is the problem?
Substantial numbers of cattle worldwide are finished in feedlot systems. Many studies have individually examined responses to protein or nitrogen additions to the diet.
Feeding systems have been developed based on aggregated data. There is a need for a comprehensive examination of the production and nitrogen balance responses to protein interventions in feedlot cattle. In particular, the merit of newer methods of evaluating production responses to protein and nitrogen intervention should be evaluated.
This study provides a quantitative evaluation of dietary and other factors that influence the production outputs critical to the profitability and environmental sustainability of cattle production in feedlots.
What did the research involve?
Conduct a meta-analysis of peer-reviewed published literature to determine:
- optimal levels of dietary protein relevant to the Australian feedlot industry taking into account the effects of Australian carcass endpoints, typical initial body weights, and mature size (gender, implants, breed) on protein requirements if possible
- effects of protein level and degradability (as expressed as crude protein, RDP/RUP, metabolisable protein, estimated metabolisable amino acid balance or estimated metabolisable amino acid balance over estimated metabolisable energy intake) on carcass gain, retained body nitrogen and nitrogen loss to the environment of feedlot cattle
- effects of protein level and degradability on dry-matter intake and efficiency of hot carcass weight gain of feedlot cattle
The adequacy of published protein systems and the protein deficit/surplus they predict (i.e. CP vs. NRC vs. CNCPS 6.55) to explain nitrogen loss from feedlot cattle. These evaluations will be limited by the number of papers reporting the relevant data for conducting estimations.
What were the key findings?
- they identified a large number of studies that evaluated responses of beef feedlot cattle to protein
- both, production responses to protein and nitrogen balance studies were identified. However, almost all studies were from the USA or Europe
- the computer-based nutrition models available provided good levels of prediction of responses to protein
There is potential to explore other strategies to increase growth of cattle in feedlots.
Critically, further studies are needed to explore:
- cattle growing at more than 2 kg/head.day
- diets based on wheat
- diets higher in true protein with detailed characterisation of the protein fractions and amino acid profiles, and the carbohydrate fractions
- diets using NPN and protected amino acids