| الوصف: |
Optimization and support of health and performance of preweaning dairy calves is paramount to any dairy operation, and natural solutions, such as probiotics, may help to achieve such a goal. Two experiments were designed to evaluate the effects of direct-fed microbial (DFM) Enterococcus faecium 669 on performance of preweaning dairy calves. In experiment 1, twenty 4-d-old Holstein calves [initial body weight (BW) 41 ± 2.1 kg] were randomly assigned to either (1) no probiotic supplementation (CON; n = 10) or (2) supplementation with probiotic strain E. faecium 669 during the preweaning period (DFM; n = 10) at 2.0 × 1010 cfu/kg of whole milk. Full individual BW was analyzed every 20 d for average daily gain (ADG) and feed efficiency (FE) determination. In experiment 2, thirty 4-d-old Holstein calves (initial BW 40 ± 1.9 kg) were assigned to the same treatments as in experiment 1 (CON and DFM). The DFM supplementation period was divided into period I (from d 0 to 21) and II (from d 22 to 63), with weaning occurring when animals were 67 d of age. During the entire experimental period, DFM was mixed into the whole milk at a rate of 1.5 × 1010 and 2.5 × 109 cfu/kg of whole milk/calf per day for periods I and II, respectively (6-time reduction). Full individual BW was taken every 21 d. As a routine of the experiment, calves were monitored daily, and diarrhea cases were evaluated using a daily 3-point fecal score. For both experiments, all data were analyzed using calf as the experimental unit. In experiment 1, DFM-supplemented calves were heavier on d 40 (+ 4.5 kg) and 60 (+ 6.5 kg) and had a greater ADG (+ 118 g) versus CON. In experiment 2, supplementation with DFM significantly tended to reduce diarrhea occurrence. Treatment × day and treatment × week interactions were observed for BW, ADG, and gain-to-feed ratio. Dairy calves supplemented with DFM were 1.8 and 3.5 kg heavier on d 42 and at weaning, respectively, and had a greater ADG from d 21 to 42 (+ 52 g) and 42 to 63 (+ 77 g) and gain-to-feed ratio from d 42 to 63 (+ 8.6%). In summary, supplementation of E. faecium 669 to dairy calves improved preweaning performance, even when the dose of the DFM was reduced by 6- to 8-times. Additionally, initial promising results were observed on diarrhea occurrence, but further studies are warranted. |
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