| Přispěvatelé: |
Trojan, Sara, Mendu, Venugopal, Jackson, Samuel P., Ballou, Michael A., Galyean, Michael L. |
| Popis: |
The objectives of the first set of experiments in steers were to evaluate: (1) effects of ionophore source in a calf starter on the performance and feed efficiency in pre-weaned calves; and (2) determine how plane of nutrition and ionophore source influence performance and ruminal fermentation in growing Holstein steer calves. In Experiment 1, one hundred eighteen Holstein calves (2 ± 1 d old) were fed a high plane of milk replacer during the pre-weaning period through 56 d of age. Calves were assigned randomly to ad libitum intake of a pelleted calf starter with either monensin (MON) or lasalocid (LAS) at 50 mg/kg (as-fed basis). Source of ionophore did not influence (P > 0.151) calf starter intake or performance during the pre-weaned period; however, LAS calves had increased (P ≤ 0.034) starter intake (2.46 kg/d) and average daily gain (ADG) (0.88 kg) after weaning. In Experiment 2a, seventy-five Holstein calves that were previously fed as described in Experiment 1 were assigned to 3 treatments in 15 pens (5 pens/treatment; 5 calves/pen) at approximately 91 d of age. Dietary treatments included: a high-concentrate diet with MON (HC-MON); high-concentrate diet with LAS (HC-LAS); and a high-forage diet with MON (HF-MON). Concentrate pellet was restricted to 4.1 kg DM/calf daily for HC-MON and HC-LAS, and was restricted to 1.6 kg DM/calf daily for HF-MON. Chopped alfalfa hay was offered ad libitum, and calves were fed this diet for 70 d. Total DM intake did not differ among diets (P > 0.177); however, calves fed HC-LAS or HC-MON, had greater (P ≤ 0.007) ADG and a tended (P = 0.070) to have improved G:F compared with those fed HF-MON throughout the grower phase. In Experiment 2b, six ruminally cannulated Holstein grower calves (4 months old; initial BW = 126 ± 6 kg) were used to evaluate ruminal metabolism and in situ degradation of both the alfalfa hay and the concentrate. Calves were fed the same diets as described in Exp. 2a (n = 2 calves/treatment). Calves fed HF-MON had greater (P ≤ 0.01) rates of DM and NDF degradation for alfalfa hay and also greater rates (P ≤ 0.06) of DM, CP, and starch degradation for concentrate compared with calves fed HC-LAS and HC-MON. In addition, HF-MON calves had increased (P ≤ 0.01) ruminal pH, acetate:propionate ratio, and methane, with lower ammonia concentrations than HC-MON or HC-LAS calves. Results suggest that calves fed lasalocid immediately after weaning would have improved performance, but switched to monensin during the grower phase. The second experiment was carried out to investigate the nutritive value, ruminal fermentation characteristics, and in situ disappearance of Chaffhaye (Alfalfa haylage preserved in a bag with added cane molasses and dried fermentation product of Pediococcus pentosaceus and Propionibacterium freudenreichii; Chaffhaye Inc., Dell City, TX) compared with alfalfa- and prairie grass hay-based diets. Each of 3 Holstein (BW = 533 ± 38.2 kg) and 3 Jersey (BW = 622 ± 60.5 kg) ruminally cannulated steers were arranged randomly in a replicated 3 × 3 Latin square design with 14 d of adaptation followed by a 7-d collection period. Animals were fed twice daily one of the following 3 experimental diets (DM basis). 1. Chaffhaye (CH); 2. alfalfa hay diet (AH) that consisted of 93.6% alfalfa hay plus 6.4% cottonseed meal; and 3. grass hay diet (GH) that consisted of 71.6% prairie hay plus 28.4% cottonseed meal. Diets were formulated to be isonitrogenous. All steers had ad libitum access to respective diets, water, and a trace mineral salt block (HI PRO feeds Inc., Friona, TX). Intakes of DM and CP were not affected (P > 0.18) by dietary treatments, but there was a tendency (P = 0.10) for steers fed GH to consume more NDF than steers in other treatments. Steers fed CH diet had a greater (P ≤ 0.001) extent of in situ DM disappearance than steers fed the AH and GH diets. Ruminal disappearance of NDF was greater (P ≤ 0.01) for steers fed CH than for GH at 12, 24, and 96 h of incubation. Ruminal CP disappearance for steers fed CH was greater (P ≤ 0.01) than for AH until 48 h of incubation. There was no treatment × time interaction (P > 0.27) for ruminal pH, but steers fed CH had a greater (P ≤ 0.01) average pH than those fed AH or GH. In vitro methane and total gas production 2 h after feeding were greater (P ≤ 0.01) for steers fed CH and AH than for GH. The greatest concentration of ruminal ammonia (P ≤ 0.01) was observed at 2 h after feeding for all diets, but ammonia concentrations were not affected by treatment or time x treatment (P ≥ 0.13). The rate of NDF disappearance of CH was similar to a high-quality, mid-maturity alfalfa hay. The CP fraction of CH was highly soluble, and the addition of soluble carbohydrate in the form of molasses might have improved microbial utilization of the soluble CP. The third experiment was performed in dogs to determine whether digestive enzymes or probiotics and prebiotic together (synbiotics) improved nutrient digestibility and fecal characteristics of adult mixed breed dogs (BW = 23.6 ± 2.45; n = 4) using a 3 × 3 Latin square design with 10-d of adaptation followed by 4-d of collection. Dogs were housed individually, and the experiment was conducted with 3 different treatments for 3 different periods. One of the treatment groups in each period had 2 dogs, whereas the other 2 groups had 1 dog (a total of 4 dogs per treatment). Each dog in a treatment was offered a commercial dog food (Adult Large Breed; Hill’s Pet Nutrition; Topeka, KS) at 1.25% of the metabolic BW at the start of each period. Body weight was measured at the beginning and end of each period. Dietary treatments included: (1) control (CON)- top dressed with 4 g/d of maltodextrin; (2) enzyme mixed diet (ENZ)- top dressed with 2 g/d of maltodextrin and 2 g/d enzyme mixture (fungal amylase, hemicellulase, xylanase, lipase, fungal protease, and acid stable protease); and (3) prebiotic and probiotics mixed diet (or synbiotics; SYN)- top dressed with 1.47 g/d of maltodextrin, 2 g/d of FOS, 0.5 g/d of MOS, and 109 colony forming units/d each of Bacillus subtilis and Enterococcus faecium. During the collection period, total feces excreted by from each dog was frozen at -80ºC for later analyses. A fresh fecal sample was taken during the last day of the collection period and analyzed for dry matter (DM), unbound water, pH, ammonia, and volatile fatty acids (VFA). Enzyme or SYN supplementation did not (P = 0.48) change BW. Nutrient digestibilities were also not influenced (P ≥ 0.64) by either ENZ or SYN supplementation. There were no differences (P ≥ 0.17) observed for the fecal DM, unbound water, ammonia, or VFA concentrations among treatment groups. In summary, results demonstrated that enzymes or synbiotics supplementation did not affect performance, nutrient digestibilities, or fecal characteristics of adult mixed breed dogs fed a commercial dog food. |
