Abstract
Supplemental n-3 fatty acids (FA) may support better immune responses than n-6 and n-9 FA in dairy calves. The objective was to evaluate the effect of n-3 FA, supplemented as a fish oil product (FO) in the milk replacer (MR), in comparison to n-6 and n-9 FA, supplemented as canola oil (CO), on body weight (BW), daily gain, and immunological parameters of preweaning Holstein calves. The study was conducted from September to December 2019. Calves were randomly allocated to a control group (n = 15; BW = 36.2 ± 1.5 kg; mean ± SEM) supplemented daily with 30 mL of CO and to an experimental group (n = 15; BW = 36.3 ± 1.5 kg) supplemented with 60 g of a product containing 30 g of FO. Both treatments were added to the MR during the morning feeding. All calves were fed 4 L of MR at 12.5% solids at 0700 and 1600 h for wk 1, 6 L from wk 2 to 7, and 3 L once daily (0700 h) during wk 8 until weaning (56 d). Blood samples were collected at 7, 14, 21, 28, 35, 42, 49, and 56 d of age for serum haptoglobin, TNF-α, IL-1β, and protectin. Dry matter intake was recorded in all experimental calves daily. Seroneutralization titers to vaccination against viral diseases (infectious bovine rhinotracheitis, parainfluenza 3, bovine viral diarrhea, and bovine respiratory syncytial virus) were determined. Mixed models for repeated measures were developed to analyze variables over time. Seroneutralization titers were analyzed by the Kruskal-Wallis test. The other variables were compared by a generalized linear model. Serum FA profile at 35 d of age showed that FO supported higher concentrations of n-3 FA than CO. Final BW [65.2 vs. 62.0 kg, standard error of the mean (SEM) = 2.1 kg] and average daily gain (0.52 vs. 0.46 kg/d, SEM = 0.1 kg/d) tended to be higher for the FO than the CO group. An interaction of treatment × day for dry matter intake was observed, especially during weaning (2.17 kg vs. 1.94 kg, SEM = 0.158 kg, for FO and CO group, respectively). Blood lactate (mmol/L) was higher in the CO than in the FO group at d 7. Haptoglobin and IL-1β were higher for the CO group on d 14 than the FO group. The TNF- α concentrations for the FO group were reduced over time, whereas the concentrations in the CO group remained constant. Protectin was higher in the FO group on d 14, but was lower on d 28, 35, and 49. Seroneutralization antibody titers postvaccination for the PI3 virus were higher for the FO than the CO group. In conclusion, calves supplemented with FO had lower concentrations of blood lactate, haptoglobin, IL-1β and TNF-α than calves supplemented with CO during the study period. The FO supplementation had a higher DMI than CO supplementation. Results of this trial should be interpreted with caution due to the lack of a negative control group as well as the lower birth weight and growth rate observed under heat stress conditions.
Highlights
The preweaning period is extremely important for dairy calves due to the close relationship between growth and health during the early stages of life and forthcoming performance as a cow (Donovan et al, 1998; Godden, 2008; Van Amburgh et al, 2019)
The hypothesis of the study was that Holstein calves fed 30 g/d of supplemental fish oil product (FO) in the milk replacer (MR) would have improved immunological responses, resulting in the potential for improved growth, as compared with calves supplemented with 30 mL of canola oil (CO)
This hypothesis is partially accepted because FO improved DMI during the last 10 d of the rearing period and modulated inflammatory mediators, supporting a tendency for a greater body weight (BW) at weaning compared with the CO group (3.2 kg difference)
Summary
The preweaning period is extremely important for dairy calves due to the close relationship between growth and health during the early stages of life and forthcoming performance as a cow (Donovan et al, 1998; Godden, 2008; Van Amburgh et al, 2019). To allow for an adequate expression of the genetic potential during the productive life, early life growth should be maximized, and morbidity and mortality rates should be minimized (Godden, 2008; Gelsinger et al, 2016). The recommended amount of milk replacer (MR) to feed varies between geographical areas in the United States (Shivley et al, 2018). Recent studies in the southeast United States have not supported higher feeding rates (>0.75 kg/d of DM) during heat stress as ADG did not increase, and abomasal disorders were reported at very high rates (Orellana Rivas et al, 2020)
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