Effects of pre-weaning supplementation with fennel seed powder in two terms on growth performance, health status, and blood metabolites of Holstein dairy calves

Abstract

This study investigated the effects of fennel seed powder (FSP) supplementation in liquid feed on growth performance, health, and blood parameters of preweaning dairy calves. In a 2 × 2 factorial design, 56 one-day-old female Holstein calves (n = 14/treatment) received liquid diet [colostrum (4.5 kg/d for the first 2 d), waste milk (6 kg/d from d 3 to 43, 5 kg/d from d 44 to 45, 4 kg/d from d 46 to 47, 3 kg/d from d 48 to 49)] supplemented with either of 3 or 6 g FSP (FSP3 or FSP6) in two terms (T: 25 or 50 d). Biometric and health traits were recorded daily, and blood metabolites were analyzed at d 25 and 50. The experiment was conducted under mild heat stress. The FSP6 group showed significant increase in starter dry matter intake (g/d and % of BW), starter crude protein (g/d), starter ether extract (g/d), starter ME (Mcal/d), total dry matter intake (g/d and % of BW), and total crude protein intake (g/d) during the last ten days of the experiment. The FSP6 group also had a significantly higher average daily gain (g/d), overall body weight (d 1–51), final weight (d 51), and total hip width compared with the FSP3 group. Feed conversion was higher in the FSP6–25 T or − 50 T groups than in the FSP3–25 T (but not −50 T) group. Calves receiving 3 g of FSP had a higher likelihood of experiencing elevated rectal temperature [≥ 39.4 ºC, odds ratio (OR) = 1.583 and confidence interval (CI) = 1.25 to 2.00], poor general appearance [(1 = normal and alert; 2 = ears drooped; 3 = head and ears drooped, dull eyes, slightly lethargic; 4 = head and ears drooped, dull eyes, lethargic; and 5 = severely lethargic); ≥ 2, OR = 1.47 and CI = 1.14 to 1.91)], and diarrhea [(1 = normal; 2 = soft to loose; 3 = loose to watery; 4 = watery, mucous, slightly bloody; and 5 = watery, mucous, and bloody); ≥ 3 (OR = 1.36 and CI = 1.04 to 1.76)] compared to those in the FSP6 group. Conversely, calves in the FSP6 group had fewer days of increased rectal temperature (4.75 vs. 7.11 d), poor general appearance (3.93 vs. 5.75 d), and diarrhea (3.85 vs. 5.11 d) than those in the FSP3 group. In addition, serum levels of alanine transferase (15.90 vs. 16.98 U/L for FSP6 vs. FSP3) and malondialdehyde (1.24 vs. 1.43 nmol/mL for FSP6 vs. FSP3) were significantly lower in the FSP6 group than in the FSP3 group. In addition, longer feeding of FSP was more effective than shorter feeding in lowering both traits. A triglyceride-lowering effect was observed in the FSP3 group compared with the FSP6 group (27.45 vs. 30.90 mg/dL). Overall, supplementation of liquid feed with 6 g FSP for 25 or 50 d improved growth performance in dairy calves.