Moisture content of high-straw dry cow diets affects intake, health, and performance of transition dairy cows

摘要

The objective of this study was to determine theeffect of adding water to a high-straw dry cow dieton feeding behavior, health, and performance of dairycows. Holstein cows (n = 40) entering their second orgreater lactation were enrolled at dry off (~45 d beforeexpected calving) and assigned to 1 of 2 dietarytreatments, consisting of a high-straw dry cow totalmixed ration [TMR; 36% wheat straw, 41% corn silage,23% pellet, on a dry matter (DM) basis, formulatedfor 11.6% crude protein, 1.35 Mcal/kg net energy forlactation] with (1) no water (CON; n = 20; DM =53.4%) or (2) water added to decrease the DM by~10 percentage points (wet diet, WD; n = 20; DM= 45.4%). Upon calving, all cows were fed the samelactating TMR (45.2% DM, 14.9% crude protein, 1.68Mcal/kg net energy for lactation) and followed for 28d. Dry matter intake, feeding behavior, and ruminationactivity were recorded automatically. Fresh TMRand orts samples were collected 2×/wk to determinedifferences in sorting. A particle separator was used toseparate feed samples into 4 fractions: long (>19 mm),medium (<19, >8 mm), short (<8, >4 mm), and fine(<4 mm) particles. Feed sorting was calculated as actualintake of each particle fraction expressed as a % ofpredicted intake. Cows fed WD had greater DM intakeduring the dry period than cows fed CON (CON = 13.4± 0.24, WD = 14.2 ± 0.24 kg/d), but rumination didnot differ (CON = 522.2 ± 8.48, WD = 518.5 ± 8.69min/d) between treatments. Cows fed WD tended toconsume their feed faster (CON = 0.08 ± 0.001, WD= 0.09 ± 0.001 kg of DM/min) compared with CONcows. Regardless of treatment, cows sorted against thelongest ration particles, with cows fed CON sortingmore against these (CON = 81.1 ± 2.51%, WD = 94.9± 2.58%). Cows fed CON tended to sort more in favorof the medium particles than those fed WD (CON =105.0 ± 0.36%, WD = 104.2 ± 0.37%). PostcalvingDM intake and feeding behavior were not affected bydry diet treatment. Cows fed WD experienced a lessrapid daily decline in rumen pH during the first 7 dafter calving compared with those fed the CON diet.The results suggest that increasing the moisture contentof high-straw dry cow diets, by adding water, mayimprove intake and reduce sorting against the longestration particles, which may help promote consistency intargeted nutrients consumed during the dry period andgreater rumen health in early lactation