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Effect of altering the ratio of dietary C16:0 and cis-9 C18:1 on production and energetic responses of lactating dairy cows: a meta-analysis.

J. M. dos Santos Neto

Abstract:

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Effect of altering the ratio of dietary C16:0 and cis-9 C18:1 on production and energetic responses of lactating dairy cows: a meta-analysis.
J. M. dos Santos Neto*1, J. de Souza2, A. M. Burch1, A. L. Lock1. 1Michigan State University East Lansing, MI, 2Perdue AgriBusiness Salisbury, MD.

We performed a meta-analysis to evaluate the effects of altering the dietary ratio of C16:0 and cis-9 C18:1 on production and energetic responses of lactating dairy cows. Treatments were: 1) CON (control; non-FA supplemented diet); 2) 80:10 (FA supplement blend with 80% C16:0 + 10% cis-9 C18:1 fed at 1.5% diet DM); and 3) 60:30 (FA supplement blend with 60% C16:0 + 30% cis-9 C18:1 fed at 1.5% diet DM). A meta-regression evaluated the relationships of insulin with energy output to milk and to BW. The data set was assembled from individual observations of 316 Holstein cows from 5 studies at Michigan State University with 80:10 (n = 113) and 60:30 (n = 113) compared with CON (n = 87). The meta-analysis was performed using the PROC MIXED of SAS, including study as random effect. Compared with CON, 80:10 did not affect DMI (P = 0.26), plasma insulin concentration (P = 0.14), BW gain (P = 0.23), or energy output to BW (P = 0.79), and increased milk yield (2.8 kg/d, P = 0.02), milk fat yield (0.13 kg/d, P = 0.01), ECM (3.16 kg/d, P < 0.01), milk fat content (0.26%, P < 0.01), and milk energy output (2.02 Mcal/d, P = 0.01). Compared with CON, 60:30 did not affect DMI (P = 0.79), tended to increase BW gain (0.21 kg/d, P = 0.08), increased energy output to BW (1.53 Mcal/kg, P = 0.05), plasma insulin concentration (0.06 �g/L, P = 0.01), milk yield (2.27 kg/d, P = 0.05), milk fat yield (0.12 kg/d, P = 0.01), ECM (3.03 kg/d, P < 0.01), and milk fat content (0.26%, P < 0.01). Plasma insulin concentration had a negative linear effect on energy output to milk (38.6 � 1.61 −7.63 � 1.74x, P < 0.01; RMSE = 1.48), and a positive quadratic effect on energy output to BW (−10.0 � 3.63 + 28.6 � 7.86x −15.2 � 4.71x2, P < 0.01; RMSE = 1.85). In conclusion, feeding FA blends between 80:10 and 60:30 increased the yields of milk, milk fat, and ECM compared with CON. Increasing dietary cis-9 C18:1 increased plasma insulin concentration, with plasma insulin concentration having a positive relationship with energy output to BW. Altering the dietary ratio of C16:0 and cis-9 C18:1 may be a useful strategy to change nutrient partitioning in dairy cows.

Keywords: insulin, oleic acid, palmitic acid.