“If you really want to push your intakes you’ve got to have beet in front of them all the time,” stressed Lincoln University’s Jim Gibbs.
Providing a fibrous supplement such as hay or straw with beet is a must but offering fibre ad-lib will just erode growth rates and increase costs, he warned.
“It’s a common sentiment that animals will balance their diets themselves so give them all the hay and straw they want, but they don’t eat to balance the rumen: they eat to make you go broke.”
Hay or straw is easy for cattle to eat and makes them feel full but they don’t realise it lowers energy intake so reduces growth, he explained.
Protein supplements such as blocks in the paddock also got a “make-you-go-broke” blast. “The only question is whether they’re the fastest or second-fastest way to go broke!”
He acknowledged there’s a “grain of truth” that raising protein content of the diet could increase growth rate but the gain is small and doesn’t justify the cost. “If you ever have to supplement protein, you’re in trouble, as a rule.”
Bulb and top combined is typically 11-13% crude protein and there’s “no class of livestock that won’t support, except finishing lambs,” he explained
Lighter R1s, 180-230kg, can have “a mild protein sensitivity” so Gibbs rules out using hay or straw as the fibre supplement for R1s as it dilutes the diet’s overall crude protein content, recommending grass or lucerne silage instead.
But for R2s or dry dairy cows such feeds are an unnecessary luxury and only add cost: use the cheapest form of fibre supplement available – typically hay or straw – and only at 2kg/head/day. As a rule of thumb, every kg of fibre eaten reduces beet intake by 1.5kg, he pointed out.
Transitioning stock onto beet needs care as too much, too soon, will cause acidosis but such problems are “entirely avoidable”, he stressed.
Host farmer Warren Leslie said they are “very careful” transitioning onto fodder beet and in four years of grazing the crop hadn’t lost one animal.
He admitted to sometimes departing from Gibbs’ recommendation to keep stock on the beet 24/7 once transitioned because he’d put hay feeders in a laneway “so they had somewhere dry to sleep at night” when it got wet in the paddock. “It probably was to the detriment of growth rate but it made me sleep better, knowing they had somewhere dry to go.”
As one of the farms in Beef + Lamb’s Fodder Beet Profit Partnership (FBPP), trials on the farm found heifer weight gains on the crop on par or slightly better than off kale or rape and grass in 2012.
In 2013, trials found no economic benefit to supplementing beet with lucerne baleage or a protein lick to boost diet protein content, one mob averaging 538g/day, another 321g/day.
This winter Murray Grey beef heifers have done 762g/day over 71 days on the crop, while two mobs of dairy heifers have done 614g/day and 694g/day. “The target liveweight gain [for the dairy heifers] in June, July and August is 300g/day.”
Putting in contractor growing costs, standardised across all the farms in the FBPP, the beet has cost Leslie $2353/ha to grow, yielding 19-25tDM/ha, to give a feed cost of 8.9-14.3c/kgDM. But as Leslie pointed out to the field day, with some of his own machinery actual cost did not exceed $2100/ha.
