Effect of increasing the amount of hay fed on Holstein calf performance and digestibility from 2 to 4 months of age

摘要

A good transition from a mainly liquid diet to a soliddiet of concentrates and forages is important consideringthe small size and development of the calf’s rumen.However, the optimal amount of hay or other highfiberingredients in the diet of recently weaned calvesis not well defined. The objective of this trial was todetermine the effects of feeding 0, 5, or 10% choppedgrass hay (6.5% crude protein, 64.6% neutral detergentfiber) with a textured, high-starch starter (20.5% crudeprotein, 38.4% starch, 14.1% neutral detergent fiber;protein pellet, whole corn, and oats) on performanceand digestion in Holstein steer calves between 2 and 4mo of age. Forty-eight calves (initial body weight = 90.7± 2.15 kg) were housed in group pens (4 per pen) andfed diets and water for ad libitum intake. Feed offeredand refused was measured daily. Calf body weight, hipwidth, and body condition score (1–5 scale) were measuredinitially and at 28 and 56 d. Fecal samples werecollected from the pen floor with care not to samplebedding material and composited by pen during d 5–9,26–30, and 47–51 to estimate apparent total-tract digestibilityusing acid-insoluble ash. Data were analyzedas a completely randomized design with repeated measuresand pen as the experimental unit. As grass hayincreased, dry matter intake (kg/d) decreased linearlybut tended to change quadratically. Dry matter intakeas a % of body weight changed quadratically with increasinghay, increasing from 0 to 5%, and decreasingfrom 5 to 10% hay. Average daily gain (1.15, 1.12, and0.95 kg/d), feed efficiency (0.336, 0.319, and 0.309 kgof average daily gain/kg of dry matter intake), and hipwidth change (4.6, 4.7, and 4.1) decreased linearly with0, 5, and 10% hay, respectively. Overall estimates of drymatter, organic matter, neutral detergent fiber, aciddetergent fiber, and crude protein digestibility changedquadratically with hay, increasing from 0 to 5%, anddecreasing from 5 to 10% hay, whereas digestibility ofstarch, sugar, and fat decreased linearly with increasinghay. Digestibility of dry matter, organic matter, neutraldetergent fiber, and acid detergent fiber increased from2 to 3 mo of age, and decreased from 3 to 4 mo of age.Digestibility of starch decreased linearly and digestibilityof fat and crude protein increased linearly withage. Digestive capacity did not appear mature by 4mo of age. Feeding 5% chopped hay supported optimaldigestion and growth in calves 2 to 4 mo of age, whichagrees with previously published research.