Grass and dairy nu­tri­tion in the late 2018 spring

Irish Examiner - Farming - - DAIRY SECTOR -

The last few weeks have brought many dif­fi­cul­ties for man­ag­ing grass and herd nu­tri­tion on dairy farms. Per­sis­tent cold wet weather has se­verely im­pacted on growth rates. Many farm­ers re­port very low cov­ers of only 300-400kg per ha on first ar­eas grazed in Fe­bru­ary, in­stead of the tar­get 500-600kg. On heav­ier land, less than 10% of area grazed at this stage is re­ported, with fer­tiliser N ap­pli­ca­tions fall­ing well be­hind tar­get also. A fur­ther com­pli­ca­tion is an emerg­ing scarcity of silage in some ar­eas, on top of the longer term short­age en­dured in the North West. Col­lec­tively, these fac­tors place in­creased pres­sure on herd man­age­ment at a busy time of year. Ev­ery farm faces its in­di­vid­ual chal­lenges. Typ­i­cal sce­nar­ios re­ported can be sum­marised as: Low grass cov­ers (un­der 600kg per ha and slow re­cov­ery), but with ad­e­quate silage stocks avail­able. Low grass cov­ers and short­age of silage in the yard. High grass cov­ers (but low per­cent­age grazed), poor ground con­di­tions, ad­e­quate silage.

High cov­ers (but low per­cent­age grazed), short­age of silage in the yard.

The main ob­jec­tives to be met in the short term are to: Feed milk­ing cows well to main­tain good milk pro­duc­tion, body con­di­tion and ru­men health.

En­sure young­stock and re­main­ing dry cows are cor­rectly fed.

Man­age graz­ing to pro­tect ground con­di­tions while util­is­ing avail­able grass. Main­tain ad­e­quate grass cover on the farm by man­ag­ing ro­ta­tion length. Pro­mote new grass growth by graz­ing win­ter cov­ers and ap­ply­ing fer­tiliser. The fol­low­ing are tips and guide­lines to meet these aims for sce­nar­ios out­lined above.

Av­er­age farm cov­ers

Mean growth rates around the coun­try were 5-7kg per ha last week, how­ever 12-18kg per day was re­ported in Bal­ly­haise, Moorepark and John­stown, and com­mer­cial farms with early N ap­plied in­di­cated some po­ten­tial pick-up in growth rates. How­ever, for many farms cor­rec­tive ac­tion will still be re­quired in the short term:

Hold­ing av­er­age farm cover above 500kg per ha in early April is very im­por­tant to al­low the farm re­spond quickly to im­prov­ing growth con­di­tions.

Farms with large ar­eas grazed and/or lit­tle to no grass need to get daily de­mand be­low growth rate to pre­vent cov­ers from fall­ing too much. If cov­ers are drop­ping rapidly, now is the time to re­duce de­mand by re­duc­ing the daily area grazed and in­tro­duc­ing sup­ple­men­tary feed. Cows must be ad­e­quately fed. Hous­ing a pro­por­tion of the herd can work well, if cu­bi­cles and feed space are un­der pres­sure.

The aim is to have at least 1100kg of DM per ha (enough grass for 80 cows for 24 hours on 1ha) back on the first pad­dock in the se­cond round. With only a 300-400kg re­cov­ery by March 22, a fur­ther 700-800kg of to­tal growth is needed be­fore the next graz­ing. It is dif­fi­cult to project growth over the next few weeks, but at a rea­son­able es­ti­mate of 30kg per day on av­er­age, ad­e­quate cover to start the se­cond ro­ta­tion will take un­til April 13-15.

The plan now should be to stretch the end of the first ro­ta­tion to that point (plus or mi­nus 3-4 days). Re­view at the end of the first week of April, and ad­just if needed. Ground con­di­tions are slowly im­prov­ing so farms with a low per­cent­age grazed, and good grass cov­ers, can get area grazed now. This must be a pri­or­ity, es­pe­cially where silage is run­ning tight. Graze some lower cov­ers to set­tle cows into graz­ing and then re­move the heav­i­est cov­ers (if dry over­head).

These pad­docks will lie dor- mant un­til new growth is stim­u­lated by graz­ing. Use on-off graz­ing if con­di­tions are mar­ginal and aim for two graz­ing bouts per day. Bring the evening milk­ing time for­ward to re­duce labour im­pact. Fer­tiliser N needs to be ap­plied as a pri­or­ity now. Aim is to have 87kg of N per ha (70 units per acre) out by the end of March. Some farm­ers on heav­ier land have brought in con­trac­tors with low im­pact ma­chin­ery (such as ATV spread­ers). Explore all op­tions. Ap­ply P fer­tiliser af­ter graz­ing heavy cov­ers, to aid root re­cov­ery.

Silage stocks, feed op­tions

As­sess avail­able silage and feed de­mand im­me­di­ately. Early ac­tion on feed deficits makes them eas­ier to solve. As a guide­line for in­take of fresh silage (22-24% DM), use 380-400kg per week for ma­ture an­i­mals (dry/milk­ing cows, bulls, in-calf heifers); 150170kg per week for young­stock (year­ling heifers). These are based on full-time hous­ing; re­duce by 40-50% if cows are grazed by day. Com­pare to­tal de­mand for the next four weeks, net of avail­able grass, to silage stocks in the yard.

Aim to have at least 1.5 weeks of silage re­serve on hand by late April. If this is un­likely, take ac­tion now to stretch sup­plies. A 30% silage deficit can be man­aged by feed­ing ex­tra con­cen­trates. Big­ger deficits will in­crease di­ges­tive prob­lem risks due to fi­bre short­ages, so for­age pur­chase may be needed. Straight in­gre­di­ents like hulls, beet pulp, and palm ker-

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