Feeding a calf starter containing highly digestible corn may improve calf growth

Models to predict dry feed intake in Holstein calves to 4 months of age

Voluntary daily dry feed intake (DFI) in Holstein calves was predicted using 60,761 individual daily observations collected from 1,235 Holstein calves in 30 experiments from 4 research stations in the United States and Europe. Consumption of dry feed (calf starter and hay, kg/d or percent of body weight) was measured from 3 to 114 d of age. Linear models and 2- and 3-parameter nonlinear models were evaluated to predict DFI using age of calf, intake of milk replacer, ambient temperature, percent forage, and neutral detergent fiber concentration in ration dry matter (DM) as independent variables. The initial data set was randomly divided within study location into development (80% of all observations) and validation data sets, and initial screening was conducted using the development data set. Five nonlinear models and 3 linear models (candidate models) were identified and used in further model evaluation. Cross-validation studies (n = 20) with the validation data set were conducted by linear regression of DFI with predicted DFI as independent variable. Candidate models were subsequently evaluated with data from 12 published studies in 2 analyses. The exponential model that best predicted daily DFI in Holstein calves in original and external data sets was DFI (kg/d) = 1.3207 × e^{[(-5.3892 + 0.6376 × MEgap) × EXP(-0.0392 × Age)]} - 0.0013 × Temp + 0.0032 × NDFDM + 0.0026 × Age × MEgap - 0.3646 × PctForage [coefficient of determination (R²) = 0.92, concordance correlation coefficient (CCC) = 0.96, and mean square error of prediction (MSEP) = 0.10 kg]; where MEgap (Mcal/d) = difference of daily metabolizable energy (ME) requirement and ME intake from milk replacer; Age = age of calf (d) from 3 to 114, Temp = mean daily ambient temperature (°C), NDFDM = ration neutral detergent fiber (% DM); PctForage = percent forage in ration DM. The linear model that best predicted DFI was DFI (kg/d = -0.1349 + 0.0106 × Age + 0.1808 × MEgap + 0.0013 × Age × MEgap + 0.0001 × Temp + 0.00002 × Age × Temp (R² = 0.93, CCC = 0.96, and MSEP = 0.10 kg). When Temp and ration characteristics were not included, optimal models were 1.4362 × e^{[(-4.6646 + 0.5234 × MEgap) × EXP(-0.0361 × Age)]} + 0.0025 × Age × MEgap (R² = 0.92, CCC = 0.96, and MSEP = 0.11 kg) and -0.1344 + 0.0102 × Age + 0.1810 × MEgap + 0.0013 × Age × MEgap [R² = 0.93, CCC = 0.96, and MSEP = 0.10 kg]. Models of daily DFI may improve prediction of nutrient supply to young Holstein calves to approximately 4 mo of age, thereby increasing prediction of growth performance.

Lactational response of early-lactation Holstein cows fed starch or floury corn silage

The study objective was to evaluate the lactational performance of early-lactation dairy cows fed a total mixed ration (TMR) based on corn silage produced from a standard starch hybrid compared with 2 floury starch hybrids. Twenty-one (6 primiparous and 21 multiparous) high-producing, early-lactation Holstein cows were blocked by calving date and parity and randomly assigned to 1 of 3 experimental corn silages from wk 4 through wk 12 postpartum using a randomized complete block design with wk 3 as a covariate. The Dekalb blend (STA; Monsanto Company, St. Louis, MO), Masters Choice 527 (LF₁; Masters Choice, Anna, IL), and Masters Choice 5250 (LF₂) treatments were planted and harvested as corn silage using a kernel processor silage harvester, inoculated, and ensiled in individual Ag-Bags (Ag-Bag, St. Nazianz, WI). The TMR were formulated to be isonitrogenous at 17.5% crude protein consisting of 15.9% alfalfa hay, 35.1% concentrate mix, and 48% of the respective experimental corn silage on a dry matter basis. Crude protein content of STA and LF₂ was lower than LF₁ corn silage. Starch content was higher for STA compared with LF₁ and LF₂ silage. The TMR digestible fiber (neutral detergent fiber) concentration was lower for STA than LF₁ and LF₂ (14.0, 15.5, and 17.9% dry matter for STA, LF₁, and LF₂, respectively). Growing crop year affected corn silage vomitoxin (0.60, 1.45, and 1.56 mg/kg) concentrations, which may have affected lactational performance as STA corn silage was from 2013, whereas LF₁ and LF₂ were from the 2012 crop year. Dry matter intake (22.9, 23.5, and 22.4 kg/d), milk yield (35.6, 34.8, and 36.1 kg/d), 3.5% fat-corrected milk yield (38.7, 36.5, and 37.6 kg/d), energy-corrected milk yield (38.2, 36.1, and 38.1 kg/d), feed efficiency (1.79, 1.61, and 1.67 kg/kg; 3.5% fat-corrected milk/dry matter intake), milk fat (4.17, 3.94, and 3.71%), milk protein (3.12, 3.09, and 3.03%), lactose (4.93, 4.92, and 4.92%), solids-not-fat (8.96, 8.92, and 8.85%), body weight change (-0.10, -0.06, and -0.08 kg/d), and body condition score change (-0.05, -0.04, and -0.05 score/d) were similar for early-lactation dairy cows fed all corn silage hybrids. Lower ruminal pH and acetate along with higher propionate molar percentages were reported for cows fed STA compared with cows fed LF₁ and LF₂. Early-lactation dairy cows fed a corn silage with lower starch and higher digestible fiber concentrations resulted in similar milk production compared with cows fed higher starch and lower digestible fiber concentrations.