Calcium salts of palm fatty acids affect production responses of mid-lactation dairy cows grazing on tropical pastures

Abstract

The objective of this study was to assess the effects of calcium salts of palm fatty acids (FA) on nutrient digestibility and the production responses of mid-lactation dairy cows grazing on tropical pastures. Twenty-two multiparous dairy cows (Jersey × Holstein) were grouped by milk yield, days in milk, and body condition score (BCS). The treatments were administered over 70-days and included: 1) control supplementation consisting of 9.0 kg d–1 of a corn-based concentrate without supplemental fat on an as-fed basis (CON), and 2) supplementation with rumen-inert fat, comprising 8.6 kg d–1 of a corn-based concentrate + 0.4 kg d–1 of calcium salts of palm FA on an as-fed basis (CSPF). All cows were kept in a rotational grazing system with elephant grass (Pennisetum purpureum ‘Cameroon’). The results indicate that, compared to the control (CON), the CSPF treatment increased the yield of milk fat, 3.5 % fat-corrected milk (FCM), and energy-corrected milk (ECM, p ≤ 0.05). The supplement did not significantly alter the contents of milk fat or milk protein (p > 0.05). However, it tended to decrease body weight gain (BWG) and dry matter intake (DMI) (p ≤ 0.10). Conversely, CSPF tended to increase dry matter (DM) digestibility (p ≤ 0.10), increase the digestibility of neutral detergent fiber (NDF) and fat (p < 0.05), and decrease plasma insulin concentration (p < 0.01). In conclusion, the addition of calcium salts of palm FA enhanced the yields of milk, milk fat, and ECM in mid-lactation grazing cows. Our findings suggest that calcium salts of palm FA can effectively partially replace a corn-based supplement for mid-lactation dairy cows grazing on tropical pastures.