Feeding Five Crossbred Cows Through the Dry Season
A farmer in Barpeta has 1.2 ha of irrigated land and five crossbred cows averaging 400 kg body weight and 12 L milk/day. The daily feed is rice straw offered free choice (about 5 kg/cow), 3 kg of a 16% crude protein concentrate, and no mineral mixture. Hybrid napier grass is available but the farmer feeds it only when convenient; the last cut was 70 days ago and stems are thick. Mustard cake, rice bran, and mineral mixture can be bought locally. The farmer wants to reduce concentrate cost without dropping milk below 11 L. There is no silage pit. The dry season starts in six weeks. Mustard cake costs Rs 45/kg, rice bran Rs 22/kg, mineral mixture Rs 60/kg, and milk sells at Rs 36/L. No ration formulation has been done; the farmer believes more concentrate means more milk.
1. Calculate the approximate daily dry matter and crude protein needs of one cow and compare them with the current ration. Identify the main shortfall and explain why simply adding more concentrate is not the best first step.
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Approximate needs for a 400 kg cow producing 12 L
- Dry matter intake at about 3% of body weight = 12 kg DM/day.
- Crude protein need: maintenance about 0.6 kg plus about 0.09 kg per litre of milk × 12 L = 1.08 kg, plus a safety margin → about 1.6–1.7 kg CP/day.
Current ration estimate
- Rice straw: 5 kg fresh × 0.90 DM = 4.5 kg DM; at about 4% CP = 0.18 kg CP.
- Concentrate: 3 kg × 0.88 DM = 2.64 kg DM; at 16% CP = 0.42 kg CP.
- Total: about 7.1 kg DM and 0.60 kg CP.
Shortfall: about 4.9 kg DM and 1.0–1.1 kg CP, plus likely energy and mineral deficiencies. The cow cannot eat enough straw to close this gap because straw is bulky, low in energy and poorly digested.
Why not just add concentrate?
- Concentrate is the most expensive part of the ration; adding 2–3 kg more would raise cost sharply and may cause acidosis or milk fat depression.
- The bigger constraint is low forage intake and poor forage quality. The napier was cut at 70 days, so stems are thick and digestibility is lower.
- Correcting forage quality and quantity first raises total DM intake, improves rumen function and lets the concentrate work efficiently. Minerals are also missing, which can limit milk and fertility even when protein is adequate, so a mineral mixture should be included before buying more oil cake.
2. Propose a practical least-cost daily ration and a six-week fodder plan that should keep milk at or above 11 L. Show the reasoning behind the quantities and the cost comparison.
Read the worked answer
Proposed daily ration per cow
- Hybrid napier, cut at 45–50 days: 30–35 kg fresh, chopped. At about 20% DM this supplies 6–7 kg DM and about 0.5–0.6 kg CP.
- Rice straw: reduce to 2–3 kg for scratch and rumen bulk, not free choice.
- Concentrate mixture: 4–4.5 kg/day, made of maize or rice bran, mustard cake, mineral mixture and salt. Example for 4.5 kg: rice bran 2.0 kg, mustard cake 1.5 kg, maize 0.8 kg, mineral mixture 0.15 kg, salt 0.05 kg. This gives roughly 3.9 kg DM and 0.7–0.8 kg CP.
- Total: about 12–13 kg DM and 1.4–1.5 kg CP, close to the target, with better energy than the straw-heavy ration.
Cost reasoning
- The concentrate mix costs roughly Rs 120–140/cow/day depending on local prices; 12 L milk at Rs 36 = Rs 432/day, so feed cost remains a reasonable share.
- Replacing part of the concentrate with good-quality napier lowers cost per kg DM compared with rice bran and mustard cake, while improving rumen function.
Six-week fodder plan
- Divide the 1.2 ha into four plots and harvest napier on a 45–50-day rotation, not 70 days.
- Apply farmyard manure and irrigate after each cut; avoid cutting too low.
- Target at least 30 kg fresh napier/cow/day; if yield is short, increase the area or buy green fodder rather than increasing straw.
- Without a silage pit, plan a small plastic-lined bunker or feed fresh daily; do not attempt large-scale silage without proper compaction and sealing.
- Weigh and record milk weekly; if milk falls below 11 L, check forage intake, water and mineral supply before adding more concentrate.