Falling milk fat in a Murrah buffalo: ration or disease?
Rajwinder Kaur keeps four Murrah buffaloes near Gurdaspur. Her best animal, a 550 kg second-calver that calved 60 days ago, gives 10 L a day and began lactation at 6.9% fat. Over three weeks her fat has fallen to 5.3%, her dung has become loose and glossy, she chews only about 35 times per bolus, and she shifts her feet and belches after the morning feed. The daily ration is 7 kg of concentrate (3 kg mustard cake, 2.5 kg maize, 1.5 kg wheat bran), about 25 kg of green berseem, and 2 kg of finely chopped wheat straw; in March she also gives 2 kg of surplus berseem at midday because it is cheap. Body condition is good, milk let-down is normal, and there is no fever, udder change or lameness. The veterinary officer records a rumen pH of 5.6 and asks whether the ration or a disease is responsible.
1. Is the low fat a ration problem or a disease? Support your answer with evidence from the case.
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It is a ration problem - subacute ruminal acidosis with milk-fat depression.
Against disease:
- Milk let-down is normal → not a udder problem such as mastitis.
- No fever, no udder change, no lameness, good body condition → not an infectious or metabolic crisis of fresh calving.
- The animal calved 60 days ago, so milk fever (which occurs at calving) is irrelevant.
For acidosis:
- Fat has fallen by 1.6 percentage points while yield has held - the classic pattern when rumen fermentation shifts away from acetate (the fat precursor) towards propionate.
- Dung is loose and glossy.
- Only ~35 chews per bolus, against a normal 55–70 → too little effective fibre.
- Rumen pH 5.6, against a normal 6.2–6.8.
- Discomfort and belching after concentrate feeding.
Cause: 7 kg of concentrate for 10 L exceeds her requirement, the maize and bran are finely ground, and the straw is chopped too fine. Berseem is about 85% water and low in effective fibre, so 25 kg of it plus fine straw still leaves the rumen short of physically effective fibre - and the extra midday berseem adds water, not fibre.
2. Rebalance the ration for 550 kg body weight and 10 L of milk. Give quantities and any additives.
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Targets: dry-matter intake about 14–15 kg/day; roughage:concentrate near 60:40; at least 18–20% crude fibre, with some long fibre; about 1 kg concentrate per 2–2.5 L of milk for a buffalo.
Suggested daily ration:
- Wheat straw 5 kg, chopped 2–3 cm - coarser than at present, so it provokes cud chewing.
- Green berseem 18–20 kg, with the surplus conserved as hay or silage rather than fed wet at midday.
- Concentrate reduced from 7 kg to 4–4.5 kg, gradually over 7–10 days, never in a single step.
- Mineral mixture 50 g and common salt 30–40 g.
- Sodium bicarbonate 100–150 g/day (roughly 1.5–2% of the concentrate), mixed into the feed.
Feeding method: divide the concentrate into three or four small feeds, always after roughage, so the rumen is not hit with a large acid load at once. Provide clean water three or four times daily.
Bypass fat: hold it in reserve. Correct the fibre first; add 100–150 g bypass fat only if fat remains depressed after 10–14 days of a properly fibrous ration.
3. How would you verify in 10–14 days that the correction worked, and what would you check if fat stays at 5.3%?
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Monitoring over 10–14 days:
- Fat should rise towards 6.5% - test twice weekly on a properly mixed sample from a complete milking.
- Chewing rate should return above 55 per bolus, with visible cudding when resting.
- Dung should firm up, and post-feed discomfort and belching should stop.
- Yield should not fall by more than about 0.5 L; if it drops sharply, the concentrate was cut too fast.
- Rumen pH, if it can be checked, should climb above 6.2.
If fat stays at 5.3% with a fibrous ration:
- Question the test first: a strip-cup or incomplete sample, or sampling a cow that was not fully milked out, can read deceptively low.
- Re-check the physical form of the straw - fine chopping slips through, so effective fibre is less than the weight suggests.
- Check water availability; restricted water lowers intake and raises the concentrate:roughage ratio in practice.
- Confirm the concentrate has not crept back up, and that berseem has not replaced dry roughage.
- Only then consider 100–150 g of bypass fat, and re-examine her energy balance - a buffalo at peak with 10 L can genuinely test slightly lower in fat than in late lactation.