The objective of this study was to evaluate growth and performance of postweaning heifers supplemented with monensin (MON), sodium butyrate (SB), or the combination of MON and SB (MSB) compared with heifers not receiving these feed additives. Forty Holstein heifers [mean age 84.2 ± 1.2 d; body weight (BW) 99.8 ± 10.8 kg (mean ± SD)] were housed in a freestall barn, blocked by birth date, and randomly assigned to 1 of 4 treatments in a randomized complete block design. Treatments were (1) 100 g of soybean meal carrier (control; CON); (2) 0.75 g of SB/kg of BW + carrier (SB); (3) 1 mg of MON/kg of BW + carrier (MON); (4) 1 mg of MON/kg of BW + 0.75 g of SB/kg of BW (MSB). Data were analyzed using single degree of freedom contrasts evaluating CON versus additives (ADD), SB versus MON, and SB and MON versus MSB. Treatments were hand-mixed daily. Feed and orts were measured daily and frozen at −20°C. Orts samples were subsampled for dry matter (DM) determination, and total mixed ration samples were taken weekly and composited monthly for DM and nutrient analysis. Initial BW, heart and paunch girths, body length, blood samples, and fecal coccidia counts were measured before the start and weekly during the 12-wk trial. Blood samples were analyzed for glucose, plasma urea nitrogen (PUN), and ketone concentrations. Apparent totaltract nutrient digestibility was determined from d 21 to 27 and from d 63 to 69 using acid detergent insoluble ash as a marker. Daily dry matter intake (DMI) and metabolizable energy intake were increased in ADD compared with CON, and average BW, final BW, and heart girth tended to increase. Whereas MSB tended to be greater than SB and MON for heart girth, feed efficiency was greater with MON compared with SB. Compared with CON, ADD decreased coccidia counts. No effect of treatment on PUN was detected. Monensin and SB tended to have greater plasma glucose than MSB did. Average blood ketone concentrations were greater with ADD versus CON, in SB versus MON, and in MSB versus SB and MON. During the wk-3 digestibility phase, DMI tended to be greater in heifers fed SB versus MON, as well as in heifers fed MSB versus SB and MON. Digestibility of nutrients were similar, except that starch digestibility was increased in heifers fed MSB versus SB and MON. During the wk-9 digestibility phase, DMI and digestibility of nutrients were similar, except NDF, which tended to be greater in CON than in ADD. Overall, ADD resulted in positive growth and reduced coccidia compared with CON.

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Objectives of this study were to evaluate apparent total tract nutrient digestibility and purine derivative (PD) excretion in dairy heifers limit-fed diets containing wet brewer’s grains (WBG) treated with salt. A 12-wk replicated 4 × 4 Latin square was conducted using 8 Holstein heifers of 224.5 ± 19.4 d of age, and body weight (BW) of 219.2 ± 28.1 kg (mean ± SD). Fresh WBG were treated with 0%, 0.8%, 1.6%, and 2.4% salt and stored for 4 d before being fed. Salt was added either to the WBG or separately to equalize the amount of salt in the diet. The diet contained 9% grass silage, 47% corn silage, 19% corn meal, 17.6% WBG and salt, 2% soybean meal, and 3% mineral mix. Diets were formulated to be limit-fed at 2.15% of BW, provide 14% crude protein (CP) and 2.27 Mcal metabolizable energy (ME)/kg of dry matter (DM). Heifers were adapted to diets for 14 d followed by a 7-d collection period. Dry matter intake (DMI) was recorded daily during the collection week while BW was recorded once a week. Urine and fecal samples were collected during the last 4 d of the collection period. Acid insoluble ash was used as an internal marker to determine apparent nutrient digestibility. Weight loss of WBG during storage was determined from days 1 to 11 and initial and final yeast and mold counts were determined. Final yeast counts were similar among treatments while final mold counts tended to be lesser (P = 0.07) for the 0.8% and 1.6% salt treatments. Urinary volume was similar among treatments while allantoin (P = 0.14), and uric acid (P < 0.01) and total PD excretion tended to increase (P = 0.13) quadratically. DMI was varied by treatment (linear, quadratic, and cubic effects P < 0.01). Heifers fed the 0.8% treatment had the least DMI. Nonfiber carbohydrate (NFC) digestibility linearly decreased (P < 0.04) as salt increased. Digestibilities of DM, and organic matter (OM), tended to decrease (P < 0.10) with increasing levels of salt added to WBG. Fat digestibility was quadratic with the greatest value for the 1.6% treatment. Treating WBG with salt reduced its deterioration based on lesser mold counts for the 0.8% and 1.6% treatments. These treatments had resulted in greater fat digestibility and tended to have increased PD excretion suggesting improved microbial protein synthesis.

The objective of this study was to evaluate the growth performance and apparent total tract nutrient digestibility of Holstein heifers limit-fed diets containing different amounts of wet brewer’s grains (WBG). A 12-wk randomized complete block study was conducted using 30 yearling Holstein heifers [378 ± 27 d of age, and body weight (BW) of 357.8 ± 27.6 kg (mean ± SD)]. Treatments were 0%, 10% and 20% of WBG on a dry matter (DM) basis and diets were formulated to be limit-fed for dry matter intake (DMI) at 2.35% of BW and provided 15% crude protein (CP) and 2.27 Mcal metabolizable energy/kg of DM. Dry matter intake was recorded daily, while BW and skeletal measurements were measured every 2 wk. During week 12, fecal samples were collected directly from the rectum over four consecutive days and composited by heifer to determine apparent total tract nutrient digestibility using acid detergent insoluble ash as a marker. Data were analyzed using the MIXED procedure of SAS. Dry matter intakes, BW, and average daily gain were not different among treatments (P = 0.2, P = 0.4, and P = 0.6, respectively). Dry matter intakes ranged from 8.6 to 9.0 kg/d. Average BW were 404.4, 411.5, and 409.3 kg for heifers fed the 0%, 10%, and 20% WBG diets, respectively. Average daily gains were 1.03, 1.04, and 0.96 kg/d for heifers fed the 0%, 10%, and 20% WBG diets respectively. Skeletal measurements and body condition scores (BCS) were not different among treatments except for the change in heart girth (P < 0.01) and initial BCS (P < 0.01). Apparent total tract digestibilities of DM, organic matter, CP, fat, and hemicellulose were greater or tended to be greater in heifers fed 0% and 20% WBG treatments than heifers fed 10 % WBG (P = 0.04, P = 0.04, P = 0.06, P = 0.06, and P = 0.01, respectively). Neutral detergent fiber, acid detergent fiber, and fat digestibilities were similar among treatments (P = 0.2, P = 0.3, and P = 0.3, respectively). During the digestibility phase, DMI tended to be greater (P = 0.08) for the 10% WBG treatment. These results demonstrate that limit-feeding heifers with diets containing up to 20% WBG could replace soybean- and corn-based concentrates in diets without adverse consequences to the heifer growth performance.