Question

2. Nevada Smith has some beef cows that average about 1100 lbs and are in late gestation, getting ready to calve. These cows require daily 27.8 lbs DM: 14 Mcal NEm: 2.80 lbs CP: 0.058 lbs phosphorus: 0.086 lbs calcium. Feeds available are sagebrush(roughage): corn (cracked) (eneral: sunflower meal (with hulls Xprotein): dicalcium phosphate (mineral); and ground limestone (mineral). Mature alfalfa hay is FIXED at 5 lbs of DM per day. In addition to determining the final amounts (amount as fed per day) of each ingredient, answer the following questions: • What is the Calcium:Phosphorus ratio (DM basis)? . What is the percentage forage in the diet (as fed; round to the nearest whole number? • What percentage of their body weight are they consuming in DM each day?

Answer 1

Proper utilization of calcium and phosphate not only depend on the mineral feeds but also on the ratio. The optimum CA:P ratio is 1.5:1, with a range of 1:1 to 4:1. In some special cases (high concentrate rations), ratios higher that 2:1 is successful. The ratio given in the data is 1.48:1 which is a normal range.

If the forage quality is average that is the TDN content is between 52% and 59%, non-lactating cows will consume about 2% to 2.1% and lactating cows about 2.3% of their body weight daily on a dry matter basis of this forage.

Cows will voluntarily consume 2.0% of body weight or 24 pound per day. This 24 pound is based on a 100% dry matter. The grass hays will always contain 7 to 10% of moisture. So the hay is of 92% dry matter and 8% moisture, then the cows will consume about 26 pounds per day on an 'as-feed basis'.