12 April 2025

Herd nutrition notes for April

March 2025 was excellent in terms of getting cows to grass and utilising swards. However, allocating sufficient grass in April can be a significant pinch point for maintaining herd performance and body condition.

Managing the transition to the second grazing rotation, milking platform stocking rate/closing area for silage production and moderate growth rates relative to demand can all impair pregrazing covers and daily allocations. Herds should be offered 18-20kg DM/day of grass, from covers of 1,400kg DM/ha to maximise grass quality and dry matter intake (DMI). Paddock size, low (<1,200kg DM/ha) or heavy (>1,600kg DM/ha) covers, and/or post-grazing residual can further compromise DMI.

Target a residual of 4 – 4.5cm to maintain intake and subsequent sward quality. On farms that are tight for grass, ideally maintain a consistent, if not increasing supply of grass, to the herd in the coming weeks in preparation for breeding.

Cows should have a minimum body condition score (BCS) of 2.75 to increase the likelihood of conception. For individual animals at 2.5 BCS or below, consider once a-day milking to reduce energy output and support partitioning of energy to BCS gain.

Increased meal feeding will not recover sufficient BCS in the short term. Heifers should be meeting body weight (BW) targets, aiming to be 60% of mature BW for mating start date, and therefore should be within 15-20kg of this target on April 1 and should have access to high-quality pasture in advance and during breeding season, particularly where synchronisation programmes are being employed.

Keep good records so that you can act quickly in response to poor performance, whether it is low submission rate, or lower than expected conception rates to first service. If there are signs of pica (licking, eating stones, branches, depraved appetite, etc.), act promptly and blood test approx. 10% of the herd to confirm suspected mineral deficiencies.

Address these immediately, but note also that over-supplementing minerals above requirements is costly, will not improve fertility, is harmful for the environment, and certain elements can cause toxicity over time.

Calculating paddock size for 36hr grazing

(cow no. x allocation x 1.5)/pre-grazing cover = ha
(120 cows x 20kg DM x 1.5)/1,400kg DM/ha = 2.6ha

Can you grow enough grass to meet herd demand?

Allocation x SR = demand
20kg DM x 3LU = 60kg DM/ha
21-22 day rotation at growth of 60kg DM/ha/day = 1,400kg DM/ha pre-grazing cover

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