In many cases, where animal performance does not meet the expectation of farmers, reduced feed intake through poor allocation of feed is a common cause. Fast growing animals require high intakes and where feed is restricted high intakes are not possible. Restricted intake may occur as a result of the daily break in a strip grazing situation being too small for the number of animals or animals spending too long in a paddock in a rotationally grazed situation. Stocking rate being too high in a set stocked system can also restrict intake. Correct allocation is critical for highly productive systems. See page 84 'Quick Guide to Hunter Grazing Management'.
Quality parameters of feed influences stock performance. For young growing animals adequate intakes of energy, protein, macro and trace elements are important for healthy and productive livestock. Specific requirements will depend on liveweight, pregnancy status and desired performance level (e.g. growth rate). Table 19, page 140 gives typical values for energy, protein and DM % of a range of feeds to help determine specific requirements.
Break feeding (strip grazing) is the best practice for manipulating utilisation rates, diet quality, crop life and crop regrowth potential. Generally, as crop utilisation increases animal intake per head decreases.
Transitioning is allowing time for the rumen microbial populations to reach a new equilibrium capable of dealing with a new feed. Theoretically this process takes 21 days to be fully complete but practically the transition is well enough advanced to minimise issues by 10-14 days. The process usually entails a gradual increase in the proportion of the crop in an animal’s diet. This can be achieved by a) the time they are left on the crop each day, or b) the daily crop allocation.
The following guidelines help to limit the effect of diet change through the transition period:
Ensure stock have ready access to a good supply of drinking water.
Brassica crops typically are highly digestible and have a high ME and protein content, but are often low in fibre. Fibre is required for efficient rumen function.
Adapted from: Drew and Fennessy, (1980) and the Lincoln University Farm Technical Manual, and Plant & Food Research Ltd data.
1 Figure adjusted to better reflect ideal harvest timing. * Drymatter content will vary depending on crop maturity, weather, and cultivar. ** NIAB Association, The Agronomist Handbook 2010/11. *** In NZ we are getting crude protein (CP) in fodder beet bulbs of between 9 and 11%.