Calving Month Feed Budget Relative Cost

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1 Autumn Calving Pattern and Fertility Guidelines for Liquid Milk Herds Liquid milk herds are facing into the highest cost period of the annual production cycle, with concentrate feeds and conserved silage now replacing grass in the diet of freshly calved cows. Additional labour and operating overheads add further cost to the system. Various economic analyses have shown that producing a high proportion of surplus-to-contract winter milk dilutes any financial benefits to be gained from winter price premiums. It is essential therefore that milk supply pattern is well-managed; central to this objective is control of herd calving pattern and fertility. This brief guide includes some information on: Costs per month of calving Cow and management factors to help improve herd fertility Feed cost per month of calving Calving date dictates the feed budget cost of the individual cow by changing the proportion of grazed grass, silage and concentrate in the annual diet. Table 1 below outlines relative costs per month for a typical 7000 litre cow stocked at 2.5LU per hectare and milked for a 300 day lactation. February is the lowest-cost month and August the most expensive. There is also a notable rise in cost for cows calving in May-July, driven by a long indoor milking period and poorer utilisation of grazed grass. At farm level, relative cost per month of calving will vary somewhat depending on annual grass growth, stocking rate etc. However, the figures presented give a good estimate for the majority of liquid milk herds operating at <4.0 cows per grazing ha. Matching calving pattern to milk contracts Summary targets for good fertility in liquid milk herds Matching calving pattern to milk contracts Given the large effect of calving date on feed costs, it is very important for liquid milk suppliers to take control of annual calving pattern. Lax calving leads to an excess of expensive winter milk, (Fig 1a) while also increasing labour input, herd health issues, and problems with youngstock management. A tighter calving pattern will significantly reduce surplus-to-contract milk (Fig 1b). This does not mean that annual milk supply or revenue is reduced, but rather that non-contracted milk is instead produced during the March-October period when it is more cost effective to do so. This pattern has 2 calving blocks, centred on early February and early October, with 75%of cows calving in the first 6 weeks of each block, and less than 5% cows recycled between seasons annually. Table 1. Total feed budget cost, relative to Feb calving Fig 1a. Lax calving pattern leading to excess winter supply Calving Month Feed Budget Relative Cost Jan 729 4% Feb Mar 721 3% Apr % May % Jun % Jul % Aug % Sep % Oct % Nov % Dec 766 9% Assumes 7000 litres per cow, stocking rate 2.6 per ha, concentrate 270 per tonne Fig 1b. Tight calving pattern leading to controlled winter supply

2 Autumn Calving Pattern and Fertility Guidelines for Liquid Milk Herds How does liquid contract affect % autumn calving? Two week blocks of calving, commencing in early February and early October, is an appropriate structure to match winter supply and contracts for most liquid milk farms. However, the relative proportion of the herd calving in each block depends on level of liquid contract. Table 2 estimates these numbers for a 100- cow herd. At low liquid milk contract levels (25% or less), calving about cows in autumn is sufficient. This raises practical issues in terms of managing small groups, particularly for with a total herd size of <100 cows. Calving cows in autumn will meet a 50% liquid contract. Note the compact spring calving, meaning that the contribution of stale (Apr-May calving) cows to December-January supply is negligible. This is efficient practice. For 70% liquid contract, it becomes more difficult to calve compactly at the optimal times while still meeting daily supply requirements. Autumn calving moves to 55 cows and should start in mid-september, with late spring calving kept to a minimum as before. With this pattern, August/early September milk supply may fall below daily targets on the individual farm, but it is argued that the benefits of block calving to the farm should be recognised in such circumstances. Some Key Practical Steps for Winter Assess current performance (Table 2). Make a plan. 2. At 50% liquid contract or less, plan to commence autumn breeding cows on Jan 1st Target 90% cows served in first 21 days breeding and 100% in first 42 days. Breed for weeks max 4. Check high risk cows (thin, twins, retained placenta) late December for uterine infection/non-cycling. Treat as appropriate before start of breeding 5. Synchronize autumn heifers to AI early Jan. Use high EBI bulls proven <1.8% calving difficulty 6. Use a team of 5-6 AI sires with EBI avg. over 260 and at least 120 for fertility index 7. Target 0% dairy stock bull. Cull, or use easy calving beef bulls, for cows with history of poor fertility 8. Assess herd BCS and UFL: PDI balance in winter diet 9. Check weights of spring replacement heifers Table 2. Monthly calving for different liquid milk contracts Calving Month Liquid Contract 25% 50% 70% Jan Feb Mar Apr May - - Jun - - Jul Aug Sep Oct Nov Dec To meet winter contracts additional to liquid litres An extra 8-10 October calving cows are needed for every 5000 litres per month of winter contract volumes (Oct to Mar inclusive), based on herds at litre annual average production. Table 2. Fertility targets for liquid milk herds Target Current Avg Calving Interval <375 days week calving rate >75% 55% % calving May to Aug <5% >10% Recycle rate <10% 23% Empty culling rate <12%? % heifers calving at months >90% 59% Herd EBI > Figures available for your herd through ICBF HerdPlus. High fertility performance, as measured by these figures, is compatible with high milk annual milk output per cow, lower feed costs, and improved labour efficiency for liquid milk suppliers. Speak to a Teagasc dairy advisor for help with these reports All information provided by Dr Joe Patton

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