05 February 2023

Laying the foundations for a successful calving season

We are fast approaching the start of the calving season on many suckler farms across the country. Stephen O’Callaghan, Walsh Scholar, Teagasc Galway/Clare, discusses how the actions taken now are the foundations for a successful calving season and year ahead.

The nutrition of the suckler cow during pregnancy is a critical factor; affecting calving difficulty, calf mortality, milk performance, retained cleanings and the ability of the cow to go back in calf. Cows should be fit not fat at calving. A body condition score (BCS) of between 2.5 and 3 is the optimum for reducing problems at calving. Body condition scoring works on a scale of 1-5, where 1 is extremely thin and 5 is extremely fat. Ideally the herd should be split into three groups when housed to allow feeding levels to be targeted to nutritional demand.

Where cows are in a BCS of between 2.5 and 3, they can be fed moderate quality grass silage (65-67 DMD) to appetite. Fat cows can have fodder restricted depending on the quality, while thin cows require ad-lib silage and may require concentrate supplementation. Where restricted feeding occurs, it is important that there is sufficient feeding space for all cows. The winter feeding strategy should be based on two stages. During the first three months of housing each group will have a different feeding strategy, with the aim to have the fat and thin cows back on track 50 to 60 days pre calving. However, during the final two months of pregnancy, the entire herd should be fed the same stable diet up to calving.

Many farms will be entering the second feeding stage in the coming weeks and it is important to reiterate that any change in BCS/liveweight should only take place in mid-gestation, as energy intake during the last two months of pregnancy goes towards the calf. 90% of calf growth occurs in the final three months of pregnancy. Over or underfeeding the cow during this period can lead to calving difficulties in fat cows. In the case of thin cows, it can lead to weak calves with poor vigour at birth. Excessive feeding in late pregnancy increases calf birth weight and reduces cow pelvic size due to fat deposition. Calving difficulty in turn reduces reproductive performance of the cow during the subsequent breeding season. Low levels of feeding during late pregnancy does not result in predictable effects on calving difficulty, as it leads to poor strength of cows to withstand calving and weak, non-vigorous calves. Cows calving in poor BCS can also take up to three weeks longer to come back in heat.

Pre-calving minerals

It is important to offer an appropriate dry cow mineral for 4-6 weeks before calving. Feeding pre-calver minerals will ensure improved colostrum quality and a lively calf at birth. Pre-calver minerals can be fed by dusting on top of silage, through water, boluses (these don’t cover macro minerals) or mollassed mineral buckets. Feeding rates of minerals may vary depending on provider, but are generally 120g/cow/day (weigh it out). If top dressing minerals on silage, carry out twice a day and ensure adequate feeding space of 1.5-2foot/cow. Don’t feed last year’s minerals. Magnesium (Mg), phosphorous (P), sodium (Na) are the major minerals required, along with a range of other trace minerals and vitamins. Calcium (Ca) supplementation is not required in dry cows and should not be fed, as this can lead to a deficiency post calving (milk fever). Table 1 below illustrates the pre-calving mineral and vitamin requirements of the suckler cow.

Table 1: Pre-calving mineral and vitamin requirements of the suckler cow

Scouring in calves

Scouring is one of the most common problems affecting young calves and can be caused by nutritional factors or by an infectious pathogen. Farms with a history of scour in calves should consider vaccinating cows to help relieve the problem. A one shot vaccine can be given to cows 12-3 weeks prior to calving, which offers protection against rotavirus, coronavirus and E.coli. The antibodies produced are then passed to the calf through the colostrum, so it is essential that the calf receives an adequate amount after birth. A calf should receive 8.5% of its total bodyweight (40kg calf = 3.5L) in colostrum during the first two hours of life, as immunoglobulin absorption reduces dramatically after then.

 Following some of these key tips can significantly reduce problems and workload during the calving season and improve overall farm profitability.