Effects of an exogenous enzyme preparation extracted from a mixed culture of Aspergillus spp. on lactational performance, metabolism, and digestibility in primiparous and multiparous cows.

The objective of this study was to investigate the effects of an exogenous enzyme preparation from Aspergillus oryzae and Aspergillus niger on lactational performance of dairy cows. Forty-eight Holstein cows (32 primiparous and 16 multiparous) averaging (± SD) 36.3 ± 8.7 kg/d milk yield and 141 ± 52 d in milk were enrolled in a 10-wk randomized complete block design experiment (total of 24 blocks) and assigned to 1 of 2 treatments: basal diet, no enzyme supplementation (CON) or the basal diet supplemented with 4.2 g/kg dry matter intake (DMI) of an exogenous enzyme preparation containing amylolytic and fibrolytic activities (ENZ). After a 2-wk covariate period, premixes with the enzyme preparation or control were top-dressed daily by mixing with approximately 500 g of total mixed ration. Production data were collected daily and averaged by week. Milk samples were collected every other week, and milk composition was averaged by week. Blood, fecal, and urine samples were collected over 2 consecutive days at 0, 4, 8, 12, and 36 h after feeding during the last week of the experiment. Compared with CON, cows fed ENZ tended to increase DMI and had increased milk concentrations of true protein, lactose, and other solids. Milk fat content tended to be higher in CON cows. A treatment × parity interaction was found for some of the production variables. Primiparous cows receiving ENZ had greater yields of milk, energy-corrected milk, milk true protein, and lactose compared with CON primiparous cows; these production variables did not differ between treatments for multiparous cows. Intake and total-tract digestibility of nutrients did not differ between treatments. Concentrations of blood glucose and total fatty acids were not affected by ENZ supplementation, but ß-hydroxybutyrate concentration tended to be greater in ENZ cows. Overall, the exogenous enzyme preparation used in this study increased milk protein and lactose concentrations in all cows, and milk production in primiparous but not multiparous cows. The differential production response between primiparous and multiparous cows was likely a result of a greater increase in DMI with ENZ supplementation in the younger animals.

Research Note: In-feed Bacteriophage does not impact efficacy of live Salmonella vaccine.

Dietary bacteriophages potentially can serve as a step to reduce Salmonella contamination of feed through direct lysis of the bacteria. However, poultry producers commonly vaccinate with live Salmonella vaccines, which could potentially be lysed by dietary bacteriophages. The objective of this study was to evaluate if dietary bacteriophages impacted the colonization of a live Salmonella vaccine. A total of 210 day-of-hatch Ross male broiler chicks were divided into 3 treatments consisting of 2 replicate per treatment. Each replicate contained 35 birds. T1 was the challenge control, given no Salmonella vaccine, T2 was challenged and given Salmonella vaccine and T3 was challenged, given Salmonella vaccine as well as dietary bacteriophage. Salmonella vaccine was administered day of hatch. On d 3, four birds/pen were sampled for Salmonella vaccine colonization of ceca and liver/spleen. The remaining birds were challenged with 5 × 107 CFU of nalidixic acid- resistant Salmonella enteritidis (S.E.). On d 28, ten birds/replicate were sampled via cloaca swabs to culture for S.E. On d 42, the trial was terminated, birds were weighed, and performance was calculated. In addition, 15 birds/replicate were sampled for cecal cultures of S.E. On d 3, T1 had 0% vaccine strain isolated, and significantly lower (P = 0.009) cecal prevalence compared with T2 (75%) and T3 (38%) being intermediate. T1 (0%) had significantly lower liver/spleen vaccine strain prevalence (P = 0.002) compared with T3 (88%) and T2 (63%) being intermediate. No significant differences (P > 0.05) were observed among treatments in Salmonella prevalence in d 28 cloacal swabs. No significant differences (P > 0.05) were observed in d 42 cecal Salmonella prevalence between all treatments. No significant differences in bird weight were observed between treatments d 0 to 42 (P > 0.05). However, T2 and T3 had lower mortality and adjusted feed conversion ratio (FCR; P < 0.05) compared with T1. Therefore, the dietary bacteriophage did not interfere with colonization or protection afforded by the live Salmonella vaccine.

Performance of dairy cows fed normal- or reduced-starch diets supplemented with an exogenous enzyme preparation.

The objective of this study was to investigate the effects of supplementation of an exogenous enzyme preparation (EEP) on performance, total-tract digestibility of nutrients, plasma AA profile, and milk fatty acids composition in lactating dairy cows fed a reduced-starch diet compared with a normal-starch diet (i.e., positive control). Forty-eight Holstein cows (28 primiparous and 20 multiparous) were enrolled in a 10-wk randomized complete block design experiment with 16 cows per treatment. Treatments were as follows: (1) normal-starch diet (control) containing (% dry matter basis) 24.8% starch and 33.0% neutral detergent fiber (NDF), (2) reduced-starch diet (RSD) containing 18.4% starch and 39.1% NDF, or (3) RSD supplemented with 10 g/cow per day of an EEP (ENZ). The EEP contained amylolytic and fibrolytic activities and was top-dressed on the total mixed ration at the time of feeding. Compared with normal-starch diet, dry matter intake and milk and energy-corrected milk (ECM) yields were lower (on average by 7.1, 9.5, and 7.2%, respectively) for cows on the RSD treatments. Concentrations, but not yields, of milk fat and total solids were increased by RSD. Energy-corrected milk feed efficiency did not differ among treatments. Total-tract digestibility of NDF tended to increase by RSD treatments. Plasma AA concentrations were not affected by treatment, except that of 3-methylhistidine was increased by ENZ, compared with RSD. Blood glucose concentration tended to be lower in cows on the RSD treatments, but ENZ increased glucose and tended to increase insulin concentrations at 4 h after feeding when compared with RSD. Cows on the RSD treatments had decreased concentrations of de novo fatty acids and tended to have increased concentrations of preformed fatty acids in milk. Overall, decreasing dietary starch concentration by 26% decreased dry matter intake, milk, and ECM yields, but ECM feed efficiency was not different among treatments. The negative effects of reducing dietary starch on production were not attenuated by the EEP.

Corn supplementation of lambs grazing alfalfa.

We investigated the effects of supplementing Rambouillet x Suffolk wether lambs grazing irrigated 'Cimarron' alfalfa (Medicago sativa L.) with three levels (0 [C0], 123 [C123], and 247 [C247] g of DM.lamb-1.d-1) of cracked corn. Each treatment group also received 190 g of a supplement designed to prevent bloat. Replicated pastures (three per treatment) grown on a fine, mixed, thermic Torretic Paleustoll soil were grazed rotationally (forage plus supplement allowance of 6.5% of BW/d) by lambs for 85 d during spring 1992. Supplemental corn levels were analyzed as single degree of freedom contrasts for linear and quadratic effects. At the start of the experiment, lambs weighed 30.7 +/- .32 kg. Average daily gains for C0 C123, and C247 were 141, 154, and 169 g/d, respectively. Lamb production per hectare increased quadratically (P < .01) with increasing corn level (C0 [716 kg of lamb/ha], C123 [816 kg of lamb/ha], and C247 [964 kg of lamb/ha]). Supplementation with C247 vs C0 increased carcass weights (11%), dressing percentage (6%), and backfat thickness (30%). Plasma urea N (PUN) concentrations did not differ (P > .10) between C0 and C123 after 27 d of corn supplementation, but after 75 d PUN concentrations between C0 and C123 had decreased (P < .10) by 11%. For C247, PUN concentrations after 27 and 75 d of corn supplementation had decreased (P < .10) by 17 and 18%, respectively, compared with C0. Plasma urea N concentrations increased (P < .01) linearly (r2 = .93) with an increase in digestible CP:DE ratio (DP:DE).(ABSTRACT TRUNCATED AT 250 WORDS)