Comparison of corn silage hybrids for yield, nutrient composition, in vitro digestibility, and milk yield by dairy cows.

A study was undertaken to compare Novartis N29-F1, a dual-purpose 90-d relative maturity corn hybrid, and Novartis NX3018, a 90-d relative maturity leafy corn silage hybrid for dry matter (DM) yield, in vitro digestibility, plant components, nutrient composition, and lactational performance by Holstein cows. The two corn hybrids were planted in replicated 15.2- x 321-m plots. Plant population and DM yield were similar between the two corn hybrids. Novartis NX3018 had higher content of crude protein and ash, a higher proportion of leaves and stalks, and a lower proportion of grain compared with Novartis N29-F1. The cob, grain, and leaves of Novartis NX3018 had higher in vitro true DM and neutral detergent fiber disappearances compared with the respective plant components of Novartis N29-F1. Thirty-eight midlactation multiparous Holstein cows (78 +/- 23.0 days in milk) producing 47.2 +/- 8.9 kg of milk per cow per day were blocked and assigned randomly to one of two total mixed ration (TMR) containing (DM basis) approximately 26% Novartis N29-F1 or Novartis NX3018 corn silage. Cows were housed in a free-stall barn and group fed ad libitum. The lactation study was conducted as a crossover design with two 28-d periods. Samples and data were collected during the final 7 d of each period. The total mixed rations were formulated using the Cornell-Penn-Miner Dairy nutrition model. Cows that were fed the total mixed rations containing Novartis NX3018 corn silage produced higher yields of milk 3.5% fat-corrected milk (FCM), milk crude protein, and milk lactose compared to cows that were fed the TMR containing Novartis N29-F1 corn silage. In conclusion, the Novartis NX3018 corn hybrid was leafier and more digestible in vitro, and when fed to dairy cows as silage, promoted higher milk yield compared with the Novartis N29-F1 corn hybrid.

Effect of corn silage hybrid on dry matter yield, nutrient composition, in vitro digestion, intake by dairy heifers, and milk production by dairy cows.

Three corn hybrids, Mycogen TMF94, Cargill F337 (which contains a brown midrib trait), and Pioneer 3861 were compared in a plot trial, an intake trial, and a lactation trial. In the plot trial, the three corn hybrids were planted in replicated 15.2 x 385-m plots. Mycogen TMF94 and Cargill F337 had lower yields of dry matter (DM), higher concentrations of neutral detergent fiber, and higher in vitro true DM disappearance compared with Pioneer 3861. Mycogen TMF94 had a higher yield of DM than Cargill F337 despite having a lower plant population. However, Cargill F337 had a higher in vitro true DM disappearance than Mycogen TMF94. In the intake trial, six individually penned Holstein heifers were blocked and assigned randomly to one of three total mixed rations containing 79% (DM basis) Mycogen TMF94, Cargill F337, or Pioneer 3861 corn silages in replicated 3 x 3 Latin squares. Heifers fed the Pioneer 3861-based TMR had lower DMI than heifers fed Mycogen TMF94 and Cargill F337-based TMR. In the lactation trial, 75 midlactation Holstein cows were blocked and assigned randomly to one of three total mixed rations containing 31% (DM basis) Mycogen TMF94, Cargill F337, or Pioneer 3861 corn silages used in the intake trial. Milk production was highest for cows fed Cargill F337-based total mixed rations. It is concluded from this study that Mycogen TMF94 was higher yielding, but less digestible, and resulted in lower milk production by lactating cows than Cargill F337. In addition, Mycogen TMF94 had higher in vitro true DM disappearance, and similar DM yield and milk production by lactating cows when compared with Pioneer 3861.

Effect of variation in proportion of cornmeal and steam-rolled corn in diets for dairy cows on behavior, digestion, and yield and composition of milk.

Sixty-six lactating multiparous Holstein cows (113+/-46 DIM) housed in a free-stall facility were blocked and assigned randomly to one of three treatments to evaluate the effects on animal performance from feeding cornmeal, cornmeal mixed with steam-rolled corn in a ratio of 1:1 on dry matter basis, or steam-rolled corn. The only difference in the dietary ingredients was the type of corn, which was included in the total mixed ration (TMR) at 17% of dry matter. The densities (g/L) of cornmeal and steam-rolled corn were, respectively, 635 and 553. Diets were fed as TMR and were formulated according to the Cornell Penn Miner Dairy nutrition model. The TMR consisted of 40% forage and 60% concentrate on dry matter basis. The first 2 wk of the 8-wk study was a preliminary period, and data collected during this period were used as covariate in statistical analysis of production data collected during wk 6 to 8. Treatment diets were fed from wk 3 to 8. Total tract digestibilities of dry matter, organic matter, crude protein, starch, and neutral detergent fiber were not significantly different among treatments. Cows fed TMR containing steam-rolled corn had higher body condition and ruminated longer. However, feeding cornmeal and steam-rolled corn together did not improve dry matter and nutrient digestion, milk yield, 3.5% fat-corrected milk yield, and percentage and yield of fat, crude protein, true protein, and lactose in milk, and milk urea nitrogen. In conclusion, feeding steam-rolled corn improved animal body condition and rumination. Partial or complete substitution of cornmeal by steam-rolled corn in diets for lactating dairy cows did not improve dry matter and nutrient digestion, milk yield, and milk composition.

Effects of dietary fiber on intake, milk yield, and digestion by lactating dairy cows during cool or hot, humid weather.

Lactating cows were offered diets with increasing neutral detergent fiber concentrations to determine the effects on intake, milk yield and composition, blood hormones, and nutrient digestion during cool or hot weather conditions. Tifton 85 bermudagrass hay was substituted for corn silage so that the forage portion of diets were: 1) 40% corn silage (control), 2) 32.4% corn silage, 7.6% bermudagrass, 3) 24.8% corn silage, 15.2% bermudagrass, or 4) 17.2% corn silage, 22.8% bermudagrass (dry basis). Dietary neutral detergent fiber concentrations (% dry matter) were 30.2, 33.8, 37.7, and 42.0, respectively. Intake of dry matter declined with increasing dietary neutral detergent fiber during cool and hot periods, but intake adjusted for cool weather treatment differences did not change further during hot weather. Milk yield declined linearly with increasing neutral detergent fiber during cool weather and changed quadratically during hot weather. Milk temperature declined with increasing dietary neutral detergent fiber for the p.m. milking during the cool period and declined with increasing dietary neutral detergent fiber for the a.m. and p.m. milkings during the hot period. Digestibility of neutral detergent fiber improved and ruminal turnover of particulate digesta was increased with greater dietary neutral detergent fiber content. No dietary fiber level by hot weather interaction was observed, suggesting that total energy intake may have and a greater effect on milk yield than dietary fiber content during hot, humid weather.

Comparison of Tifton 85 and Coastal bermudagrasses for yield, nutrient traits, intake, and digestion by growing beef steers.

A study was undertaken to compare Tifton 85 (T85) and Coastal (CBG) bermudagrasses for effects of cultivar and age at harvest on yields of DM and digestible DM, in vitro digestion, nutrient content, cell wall composition, in situ digestion kinetics, and feed intake and digestion by growing beef steers. In Exp. 1, T85 and CBG forages staged for growth in May or July of 1993 were harvested at 3, 4, 5, 6, 7, and 8 wk from subplots. Tifton 85 bermudagrass had 7.1% greater DM yield, 18.2% higher (P < .05) digestible DM yield, and 7.1% greater IVDMD than CBG, and, after 5 wk of forage growth, IVDMD of both T85 and CBG decreased with increased age at harvest (P < .05). In Exp. 2, T85 and CBG forages staged for growth in July 1997 were harvested at 2, 3, 4, 5, 6, and 7 wk from subplots. Even though T85 had higher concentrations of NDF and ADF than CBG, T85 had 34.1% higher DM yield, 47.9% higher digestible DM, 55.0% higher digestible NDF, 91.7% higher digestible ADF, greater IVDMD, in vitro NDF and ADF disappearances, and higher in situ DM and NDF digestion (P < .05). Coastal bermudagrass had higher concentrations of lignin and lower concentrations of total neutral sugars, arabinose, glucose, and xylose than T85 (P < .05). In vitro digestibilities of DM, NDF, and ADF were lower and concentrations of ADF and lignin were greater for 7- vs 6-wk harvests of both T85 and CBG (P < .05). In Exp. 3, T85 and CBG forages staged for growth in July 1997 were harvested as hay at 3, 5, and 7 wk from .8-ha pastures and fed to 36 individually penned growing beef steers (initial BW = 244 kg) to quantify ad libitum intake without supplementation. Tifton 85 bermudagrass had lower concentrations of lignin and ether-linked ferulic acid and greater concentrations of NDF, ADF, hemicellulose, and cellulose than CBG (P < .05). Steers fed T85 had higher (P < .05) digestion of DM, OM, NDF, ADF, hemicellulose, and cellulose than steers fed CBG. Digestion of NDF, ADF, hemicellulose, and cellulose decreased (P < .05) with increased age at harvest for both cultivars. In conclusion, T85 produced more DM and had more digestible nutrients in vitro, in situ, and in vivo than CBG, and 3 and 5 wk of growth would be recommended ages to harvest either cultivar.

Intake, milk yield, and digestion by dairy cows fed diets with increasing fiber content from bermudagrass hay of silage.

Lactating dairy cows were offered diets containing increasing quantities of Tifton 85 bermudagrass hay or silage and increasing dietary neutral detergent fiber (NDF) to determine effects of method of bermudagrass storage and dietary fiber content on intake, milk yield, and nutrient digestion. Bermudagrass was added as hay or silage at the rate of 8.5, 15.9, or 23.3% of dietary dry matter and was substituted for an equal quantity of corn silage. The method of bermudagrass storage did not affect intake [20.8 vs. 20.3 (+/- 0.3) kg/d for bermudagrass hay and silage diets; respectively], but an increase in the amount of bermudagrass and NDF in the diet did reduce intake. Dietary NDF concentration was well above minimum recommendations of the National Research Council. Milk yield was not altered by method of bermudagrass storage but declined as dietary NDF increased. Digestion of NDF tended to be lower for bermudagrass silage than for bermudagrass hay. An increase in the amount of bermudagrass in the diet improved digestion of dietary dry matter, acid detergent fiber, and NDF; however, milk yield declined because total intake declined. Improved NDF digestion caused by added bermudagrass hay or silage was confirmed by in vitro analyses. High quality bermudagrass hybrids could potentially be used in diets of lactating dairy cows because of the good digestion characteristics and relatively small effects on intake despite the high dietary fiber content. Tifton 85 bermudagrass may serve as a forage alternative for lactating dairy cows.