(Abstracted from an article published by Alvarez and others Trop Animal Production: 1980, 5: 1-13)
An Indian tradition followed by farmers where calves are allowed to suckle while milking Indian breeds of cows. Research has proved that this practice has sound scientific basis. Data from 539 lactations of Zebu crossbred cows at Tabasco State in Mexico was analysed for effect of presence or absence of calves at the time of milking on milk production and calf health. Over 95% of Tabasco has a hot, humid tropical climate. The average annual temperature is 27 °C (81 °F) with high temperatures averaging 36 °C (97 °F) mostly in May and lows of 18.5 °C (65.3 °F) in January. The flat areas of the state are subject to frequent flooding. The dairy cow feeding system is largely grazing with little concentrate feed supplementation when pasture availability is low. In the experiment two sets of milking was followed; with and without calf suckling. The lactation data of these cows was collected and analysed.
The results revealed that 40% of the cows that were milked without calves being present had shorter lactations with reduced saleable milk. The remainder cows in this group (60%) which appeared to give normal milk in first lactation had shorter lactation length and less milk production in subsequent lactation under the same management system. Interestingly, when these cows in subsequent lactations were milked in the presence of calves, they yielded normal milk production spanned over normal lactation length (290-300 days). The restricted suckling system in which calves were first shown to cows for suckling and stimulation of letting down was found to be most appropriate since over a total of 230 lactations the average yield of saleable milk was 1120 litres in 262 days. There was also reduced incidence of subclinical mastitis. In group where calves after weaning at birth were reared artificially, low growth rate (277 g/d) and high mortality were observed. However these problems reduced significantly when the calves were reared by restricted suckling as growth rate increased to an average of 464 g/d and mortality reduced to 6 %.
Lesson for Indian farmers: Indian breeds of cows (including crossbreds) are known to have high maternal instinct, hence a system wherein calves remain present for stimulation at the time of milking (even with machine milking) would result in higher milk production for more days. In case the farmer is not able to maintain proper calf feeding hygiene, it is always better to let the calf suckle one teat. However, this arrangement may not work if you intend to feed milk replacer. Another difficulty is control over amount of milk taken by the calf.