A wheat-straw ration for crossbred cows and a plan to add urea
A farmer near Rohtak keeps 20 crossbred cows, of which 10 are in milk averaging 12 L a day with 3.2% fat. The daily ration per cow is 7 kg wheat straw, 2 kg mustard cake, 1 kg wheat flour and 20 g common salt. No green fodder is fed because berseem finished in April and the farmer says green fodder is 'not available' in June. The cows are losing body condition, several have a rough coat and one shows signs of oestrus every 10 days. The farmer wants to add 1 kg of urea to the concentrate to save money on oil cakes. Locally available feeds are maize green fodder at about ₹1.5 per kg, cotton seed cake, molasses and wheat straw.
1. Assess the present ration and state its major deficiencies with rough figures.
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Dry-matter intake is about 9 kg per cow: 7 kg wheat straw (about 6.3 kg DM), 2 kg mustard cake (1.8 kg DM) and 1 kg wheat flour (0.87 kg DM).
Energy: wheat straw supplies only about 2.5 kg TDN, mustard cake about 1.4 kg and wheat flour about 0.8 kg, giving roughly 4.7 kg TDN. A 12 L cow needs about 7.0–7.5 kg TDN, so there is a deficit of about 2.5 kg.
Protein: straw gives about 0.2 kg CP, mustard cake about 0.5 kg and flour about 0.1 kg, totalling roughly 0.8 kg against a requirement of about 1.5 kg - a deficit of about 0.7 kg CP.
Minerals and vitamins: no mineral mixture, salt only 20 g against a need of 40–50 g, a wide calcium-to-phosphorus imbalance because straw is low in calcium and mustard cake is high in phosphorus, and no carotene from green fodder. The rough coat, poor body condition, low milk fat and irregular oestrus fit energy, protein and mineral deficiency. Wheat straw also gives a bulky ration that limits intake.
2. Formulate a more balanced daily ration per cow using the locally available feeds, and show that it meets requirements approximately.
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Suggested ration per cow per day: wheat straw 4 kg, maize green fodder 15 kg, cotton seed cake 2 kg, mustard cake 1 kg, molasses 0.5 kg, mineral mixture 100 g and salt 50 g.
Approximate supply: wheat straw gives about 1.4 kg TDN and 0.15 kg CP; maize fodder gives about 1.8 kg TDN and 0.25 kg CP; cotton seed cake about 1.4 kg TDN and 0.6 kg CP; mustard cake about 0.7 kg TDN and 0.3 kg CP; molasses about 0.3 kg TDN. Total is about 5.6 kg TDN from these feeds plus the energy from any additional concentrate, and about 1.3 kg CP. If the farmer can afford 1 kg more of a cereal-based concentrate, TDN reaches about 6.4 kg.
Feeding plan: feed green maize fodder and concentrate in the morning and evening, keep straw available at midday, mix mineral mixture into the concentrate, and introduce any new feed over 7–10 days. Berseem in winter can replace part of the maize fodder. This ration is cheaper than raising oil cakes alone because maize fodder supplies energy at low cost, while cotton seed cake supplies both energy and protein.
3. The farmer wants to add 1 kg urea per cow per day. Evaluate this proposal, including the correct way to use urea if it is used at all.
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One kilogram of urea per cow per day is dangerous and cannot replace oil cake. Urea supplies nitrogen, not energy, and rumen microbes convert it to microbial protein only when readily available energy is present. At 1 kg it would be roughly 10% of dry-matter intake and would almost certainly cause ammonia toxicity, with salivation, bloat, muscle tremors, ataxia and death within 20–30 minutes.
Correct use, if any: urea should supply no more than about 1% of the concentrate or 0.5% of total dry matter, be introduced over 2–3 weeks, and be fed with a high-energy source such as molasses, maize or wheat flour, never with green fodder alone or on an empty stomach. Even then it only partially replaces protein; a 12 L cow needs bypass protein from cotton seed cake or mustard cake, which urea cannot provide. For this farmer the immediate priority is more energy and green fodder, not urea. Advise at most 100 g urea mixed into the concentrate after the ration has been corrected, and keep molasses in the ration to supply fermentable energy.