Effects of corn grain endosperm type and conservation method on feed intake, feeding behavior, and productive performance of lactating dairy cows

摘要

Our objective was to evaluate the effects of corn grainvarying in endosperm type and conserved as high-moistureor dry ground corn on dry matter intake (DMI),feeding behavior, ruminal fermentation, and yields ofmilk and milk components of cows in early to midlactation.Seven ruminally and duodenally cannulatedHolstein cows (73 ± 39 d in milk; mean ± SD) wereused in a duplicated 4 × 4 Latin square design with 21-dperiods. A 2 × 2 factorial arrangement of treatmentswas used with main effects of corn grain endospermtype (floury or vitreous) conserved as high-moisturecorn (HMC) or dry ground corn (DGC). Rations wereformulated to contain 27.0% starch, 26.6% neutraldetergent fiber (NDF), 19.1% forage NDF, and 16.5%crude protein. Corn grain treatments supplied 86.6% ofdietary starch and contained alfalfa silage as the soleforage. Dry matter intake was increased 1.3 kg/d byDGC compared with HMC. The increase in DMI byDGC was related to a shorter intermeal interval (104.4vs. 118.2 min/d), and meal size was not affected bytreatment. Dry ground corn decreased rumination boutlength and number of chews per bout compared withHMC. No differences were detected between endospermtreatments for DMI, yields of milk, 3.5% fat-correctedmilk (FCM), milk fat, protein, lactose, or solids-notfat(SNF). Mean yield of 3.5% FCM across treatmentswas 47.5 kg/d. However, a tendency for an interactionwas observed for feed efficiency; floury endosperm increasedefficiency 0.05 kg 3.5% FCM per kg of DMI forDGC but decreased it by 0.14 kg 3.5% FCM per kg ofDMI for HMC relative to vitreous endosperm. Vitreouscompared with floury corn tended to increase trueprotein concentration in milk when conserved as DGC(2.68% vs. 2.62%) but not as HMC. Concentration ofSNF was increased by DGC compared with HMC (8.45vs. 8.37%) due, in part, to the effect of treatment onmilk protein concentration. Body weight was not affectedby treatment, but vitreous endosperm tended toincrease loss of body condition compared with flouryendosperm. Corn endosperm type and conservationmethod had little effect on productive performance ofhigh-producing cows.