Charlotte Westwood BVSc, MANZCFS, PhD, Veterinary Nutritionist; PGG Wrightson Seeds
Key drivers for gaining efficiency from high quality forages are getting more lambs finished rather than sold as store, and earlier (which reduces parasite loading), and hogget mating options. Crop options include chicory, plantain, brassicas and irrigated short rotation pastures, with the aim of more energy and protein, less fibre and better mineral profiles. Focus on quantity and quality of feed, transition from pasture, minimising clinical and sub-clinical disease and internal parasites, and trace minerals. Dry matter intake (DMI) is important – lambs that eat more grow more. Aim to offer 5-7% of liveweight to young lambs for rapid growth, to give 4% eaten from 8 – 10 weeks of age.
DMI is bite rate x bite size x biting time. Sheep graze 83-93 mg/bite. DMI levels out at around 4-6cm sward height for lambs (vs. >8-10cm for cattle). Lambs selectively graze (green over dead material, legumes over grass) and will mix and match when offered a choice of monocultures. Lambs can adjust bite rate which cattle cannot. Feed is chewed a lot more before swallowing. Lamb finishing challenges include transition from pasture to crop and increased risk of animal health issues. Time of transition depends on how lambs have been backgrounded and the type of crop.
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