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. 2021 Dec 14;11(12):868. doi: 10.3390/metabo11120868

Table 1.

Least squares means and 95% confidence intervals of performance variables and blood metabolites of low (high efficient, HE) and high (low efficient, LE) residual feed intake (RFI) mid-lactation primiparous and multiparous dairy cows enrolled in 45-day feed efficiency studies.

RFI Group 2 Parity 3 p-Value 4
Item 1 HE LE Primiparous Multiparous RFI Group Parity Interaction
Intake and body composition
 DMI, kg/day 25.1 [24.1, 26.0] 29.1 [28.2, 30.0] 24.0 [22.9, 25.0] 30.2 [29.4, 31.0] <0.0001 <0.0001 0.35
 DIM 115 [95, 134] 115 [95, 135] 111 [92, 130] 119 [97, 140] 0.97 0.27 0.40
 BCS 3.4 [3.2, 3.5] 3.3 [3.2, 3.4] 3.4 [3.2, 3.6] 3.3 [3.2, 3.4] 0.39 0.08 0.85
 Body weight, kg 686 [662, 710] 693 [669, 717] 636 [608, 662] 744 [724, 764] 0.68 <0.0001 0.92
 Body weight change, kg/day 0.60 [0.27, 0.93] 0.57 [0.24, 0.90] 0.51 [0.18, 0.83] 0.66 [0.29, 1.03] 0.80 0.20 0.61
Milk production
 Milk yield, kg/day 44.5 [38.9, 50.0] 42.6 [37.0, 48.1] 35.9 [28.4, 43.5] 51.1 [45.9, 56.3] 0.29 <0.0001 0.81
 Milk energy output, Mcal/day 30.0 [28.4, 31.5] 30.0 [28.1, 31.2] 26.0 [24.2, 27.8] 33.6 [32.3, 34.9] 0.79 <0.0001 0.96
 Milk fat concentration, % 3.4 [2.6, 4.2] 3.7 [2.9, 4.7] 3.8 [3.1, 4.5] 3.3 [2.5, 4.1] 0.08 0.01 0.72
 Milk fat yield, kg/day 1.48 [1.38, 1.58] 1.50 [1.41, 1.60] 1.36 [1.25, 1.47] 1.63 [1.54, 1.71] 0.72 0.0002 0.84
 Milk protein concentration, % 3.05 [2.97, 3.14] 3.16 [3.07, 3.24] 3.23 [3.13, 3.32] 2.98 [2.91, 3.05] 0.08 <0.0001 0.28
 Milk protein yield, kg/day 1.35 [1.15, 1.54] 1.32 [1.13, 1.52] 1.16 [0.93, 1.38] 1.51 [1.33, 1.69] 0.64 <0.0001 0.83
Blood metabolites
 Glucose, mg/dL 70.8 [62.2, 79.4] 71.3 [62.6, 79.9] 70.9 [62.6, 79.2] 71.2 [62.1, 80.2] 0.68 0.85 0.54
 NEFA, mmol/L 0.14 [0.12, 0.15] 0.13 [0.12, 0.15] 0.14 [0.12, 0.15] 0.13 [0.12, 0.15] 0.47 0.79 0.12
 Triglyceride, mg/dL 11.2 [10.3, 12.0] 10.8 [9.9, 11.7] 10.7 [9.8, 11.6] 11.3 [10.3, 12.2] 0.55 0.37 0.78
 BHB, mmol/L 0.64 [0.58, 0.70] 0.62 [0.55, 0.68] 0.65 [0.58, 0.72] 0.60 [0.54, 0.67] 0.60 0.28 0.14

1 DMI = dry matter intake; DIM = day in milk; BCS = body condition score; NEFA = non-esterified fatty acids; and BHB = β-hydroxybutyrate. 2 HE, n = 28; and LE, n = 28. 3 Primiparous, n = 20; and Multiparous, n = 36. 4 RFI Group = effect of RFI Group; Parity = effect of parity; and Interaction = effect of the interaction of RFI Group and Parity.