Production response in dairy cows milked two or three times a day: A meta-analysis

Abstract

The objective was to evaluate the effects of two (2×) vs three (3×) times per day milking on milk production and milk composition in dairy cows. Fourteen scientific papers, containing production data from 16 trials, where dairy cows were milked 2× or 3×, were analysed using meta-analysis with fixed and random-effects with the R statistical program. The degree of heterogeneity and publication bias were measured with the I2 statistic and Begg’s test, respectively. In addition, the meta-regression analysis explored other sources of heterogeneity for the response. The estimated effect size of 2× and 3× milkings was calculated for dry matter intake (DMI), milk production, and milk composition. Dry matter intake, milk production, and milk fat and protein yields showed substantial heterogeneity (I2>50%). Whereas milk fat-percentage had moderate heterogeneity (I2<50%), and milk protein had no (I2=0%)heterogeneity. The year of publication, trial duration, and cattle breed did not influence production response parameters to milking frequency. We found no evidence of publication bias for the parameters evaluated (Begg’s test; P>.05). Cows milked 2× produced less milk (2.23 kg/d), less milk fat (0.06kg/d), and less milk protein (0.05 kg/d). In contrast, the fat percentage was lower (0.07 units) in 3×, compared with 2× milking frequency. There was no effect of milking frequency on DMI and milk protein percentage. In conclusion, milk production and milk fat and protein yields improves as milking frequency increase from 2× to 3× daily, without affecting DMI. The implementation of 3× milking frequency must consider dairy cow management, labor, and milking parlour infrastructure, particular to each dairy farm.

The Influence of Energy Balance, Lipolysis and Ketogenesis on Metabolic Adaptation in Cows Milked Twice and Three Times Daily

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Can Small-Scale Dairy Farm Profitability Increase with the Use of Solar Energy Technology? An Experimental Study in Central Tunisia

“…Milk production increases with age [49]. Consequently, the milk production of a dairy cow will increase according to its number of lactations, leading to an increase in the number of working days from the initial 275 days to 305 days, which is an optimal scenario.…”

Analyses of Operational and Economic Conditions in Selected Dairy Farms

“…The authors identified some risk factors; increased parity, later stage of lactation, not milking clinical and subclinical cases last, lack of routine cleaning of the milking parlour, using the dry-off treatment and optimized feed before calving. According to Sánchez-Duarte et al (2020), increasing milking frequency from twice to three times per day positively affects milk production and yields of milk fat and milk protein without increasing dry matter intake. Application of three times per day milking frequency must consider dairy cow management, labour availability, and milking parlour infrastructure particular to each dairy farm.…”