META-ANALYSIS OF PHYTOGENIC ADDITIVES FOR BROILERS

Phytogenic additives have been studied intensively in broiler chickens’ production to substitute growth-promoting antibiotics. However, the comprehensive literature on this topic makes it difficult to understand overall results because there are a noticeable number of studies with conflicting conclusions. While several research studies have shown that phytogenic additives may increment broiler chicken’s performance, others make the opposite evident. This study aimed to organize and understand information through meta-analysis considering a great number of publications and the factors that may interfere in the results of phytogenic additives, evaluating whether phytogenic additives can be used as a performance-enhancing additive for broilers, comparing with the effectiveness of growth-promoting antibiotics. The main factor that interferes in the evaluation of phytogenic additives is the microbiological challenge. Phytogenic additives improved average daily gain (ADG) (P < 0.001) and feed conversion (P < 0.001) regardless of microbiological challenge; however, they were worse compared to antibiotics under higher challenge (P < 0.020). A meta-regression of ADG in function of average daily feed intake confirmed that phytogenic additives increased the feed efficiency of broilers, but with less effectiveness than antibiotics. The blends of phytogenic additives increased the ADG in relation to the isolated use of only one phytogenic additive.

The Importance of B Vitamins in Enhanced Precision Nutrition of Dairy Cows: The Case of Folates and Vitamin B12

Dairy cow diets are generally balanced for energy and major nutrients with B vitamins generally assumed not to be limiting, in spite of their role as coenzymes, essential to many metabolic reactions in protein, carbohydrate and lipid metabolism. Assuming adequacy of B-vitamin supply may explain some of the discrepancies between the outcomes of metabolic prediction models and measured cow performance. In lactating dairy cow, the amount of B vitamins from the diet and synthesized by the ruminal microbiota is generally sufficient to prevent deficiency symptoms and, as such, is assumed to fulfill requirements. However, reports of beneficial effects of B-vitamin supplementation on dairy cow performance suggest that B-vitamin supply is sometimes lower than its needs, as an insufficient B-vitamin supply decreases metabolic efficiency by driving a shift towards alternative metabolic pathways with greater energy cost. Using information on folates and vitamin B12 illustrated how meeting dairy cow needs for B vitamins should not be overlooked in formulation of rations for lactating dairy cattle. The present review discusses current knowledge and indicates areas presently impeded by the lack of research results, especially the limitations on the ability to estimate B vitamin need and supply.

Are muscle fiber types different between normal and dark-cutting beef?

Muscle fiber (MF) characteristics of Longissimus thoracis (LT) muscles from heifer (n = 11) and steer (n = 12) carcasses graded Canada AA (AA, normal, n = 4/sex) or dark-cutting (Canada B4) were examined and related to beef quality. Atypical (AB4, pH < 5.9, n = 4/sex) and typical (TB4, pH > 5.9, n = 3 and 4 for heifers and steers, respectively) dark-cutting carcasses were represented. Muscle fiber type proportions did not differ between AA, AB4 and TB4 muscles, although type I and IIB muscle fiber diameters were greater in TB4 than in AA LT. That AB4 muscle fiber proportions were not different from AA and TB4 muscles suggests that the increased MF diameter of TB4 muscle was due to water retained by muscle proteins at high ultimate pH, as evidenced by decreased cooking loss. Dark-cutting was therefore unrelated to muscle fiber proportions, and increased Type I and IIB diameters in dark cutting LT were likely driven by elevated intramuscular ultimate pH.

Evaluation of antimicrobial compounds to inhibit growth of select Gram-positive pathogenic or antimicrobial resistant bacteria in air-exposed silage

Spoiled silages can harbor pathogenic and antimicrobial-resistant microbes. The potential of some antimicrobial additives to inhibit certain pathogenic and antimicrobial-resistant bacteria in air-exposed silage was measured using pure and mixed bacterial cultures. With pure cultures, laurate and monolaurin (5 mg·mL−1) caused decreases (P < 0.05) of 4 to >7 log10 colony-forming units (CFU)·mL−1 in Listeria monocytogenes and Enterococcus faecalis compared to controls. Ten-fold higher amounts of these inhibitors were needed to equivalently decrease staphylococci. 2-Nitropropanol (1 mg·mL−1) decreased (P < 0.05) E. faecalis and L. monocytogenes 2.9–3.8 and 2.4–7.2 log10 CFU·mL−1 after 6 and 24 h incubations, respectively. In air-exposed whole-plant corn silage the inhibitors caused decreases, although not necessarily significant, of 0.7–2.2 log10 CFU·mL−1 in L. monocytogenes, staphylococci and culturable aerobes after 24 h incubation, with modest yet significant (P < 0.05) inhibition (<0.1–0.3 log10 CFU·mL−1) of yeasts and molds. Tests for carry-over effects against ruminal microbes revealed laurate, monolaurin, and 2-nitropropanol inhibited methanogenesis by >50% (P < 0.05) after 24 h incubation and inhibited L. monocytogenes and enterococci. The antimicrobial activities exhibited by these compounds may yield opportunities to optimize their use to rescue spoiled silages.

Enzyme complex addition in barley or rye broiler diets with two energy levels fed from 1 to 21 days

Two experiments were conducted to evaluate diet digestibility, performance, digestive parameters, and blood parameters when an enzyme complex (EC) was used in barley- and rye-based diets with different energy levels. In the digestibility assay (exp. I), 108 seventeen-day-old Cobb male broilers were distributed in a completely randomized design in 2 × 2 × 2 + 1 factorial arrangement with two feeds (barley or rye), two EC levels (0% and 0.02%), and two energy levels [3025 and 3125 kcal apparent metabolizable energy (AME)·kg−1], plus a control treatment. In exp. II, 1080 one-day-old Cobb male broilers were distributed in a completely randomized design in 2 × 2 × 2 + 1 factorial arrangement with two feeds (barley or rye), two EC levels (0% and 0.02%), and two energy levels (2875 and 2975 kcal AME·kg−1). No interactions were observed for any variables (exp. I and II). Enzyme complex improved the apparent metabolizable coefficient of gross energy (P = 0.0432) of diets. The EC provided greater weight gain (P = 0.0003) and better feed conversion (P = 0.0025). Intestinal viscosity at 21 d was reduced (P < 0.0001) with the addition of the EC. The EC improved nutrient digestibility and performance, but the effects of energy reduction on performance could not be overcome.

Achyranthes Japonica Nakai root extract supplementation improves apparent nutrient digestibility, caecum microbiota, and excreta gas emission in broiler chicks

This study investigated the effects of supplementing Achyranthes Japonica Nakai (AJN) root extract to the diet of broiler chicks on growth performance, nutrient digestibility, caecum microbiota, excreta gas emission, and relative weight of organs. A total of 270 1-day-old Ross 308 broiler chicks (42.11 ± 0.18 g) were randomly allotted into 3 dietary treatments according to the initial body weight. Each treatment had 5 replicate cages with 18 birds per cage. The experimental period was 35 days (starter, days 1-7; grower, days 8-21; finisher, days 22-35). Dietary treatments were corn-soybean meal-based basal diet supplemented with 0.000, 0.015, or 0.030 % AJN root extract. The apparent total tract digestibility of nitrogen (P = 0.025) increased linearly with the increase of the dosage of AJN root extract, while the counts of E. coli in caecum (P = 0.038) and excreta ammonia emission (P = 0.003) decreased linearly. However, the growth performance (P > 0.05) and the relative weight of organs (P > 0.05) did not differ among the dietary groups. In conclusion, AJN root extract could increase the nutrient digestibility and reduce the noxious gas emission by reducing the caecum harmful microbiota in a dose-dependent manner.

Effect of dietary organic acids supplementation on growth performance, nutrient digestibility, and gut morphology in weaned pigs

This study was conducted to investigate the effects of dietary supplementation with different organic acid (<b>OA</b>) mixtures on growth performance, nutrient digestibility, and gut morphology in weaned pigs. A total of 56 weaned pigs (7.93 ± 1.04 kg body weight) were assigned to four dietary treatments with seven replicates per treatment for a 35-d study conducted over two phases; phase 1 (d 1 to 14) and phase 2 (d 14 to 35). Diets consisted of 1) a corn-soybean meal-basal diet without any additive (negative control, <b>NC</b>); 2) NC + formic and propionic acids (<b>TRT1</b>); 3) NC + butyric, formic, and propionic acids (<b>TRT2</b>); and 4) NC + antibiotic (positive control, <b>PC</b>). During the overall period, the gain to feed ratio of pigs fed the PC and TRT1 diets tended to be higher (<i>P</i> = 0.059) than that of the NC diet. However, OA supplementation had no effects on nutrient digestibility. Jejunal villus height to crypt depth ratio was higher (<i>P</i> < 0.05) in pigs fed the TRT1 diet than those fed the NC diet. In conclusion, dietary OA supplementation tended to increase overall feed efficiency and improved gut morphology in weaned pigs.

Evaluating the effects of fibrolytic enzymes on rumen fermentation, omasal nutrient flow, and production performance in dairy cows during early lactation

This study was performed to evaluate the effects of pre-treating a barley-silage-based diet with an exogenous fibrolytic enzyme derived from Trichoderma reesei (FETR, a mixture of xylanase and cellulase) on lactation performance, omasal nutrient flow and digestibility, rumen fermentation characteristics, and rumen pH profile in Holstein dairy cows during early lactation. The dairy trial was conducted using nine Holstein dairy cows (averaging 46 ± 24 days in milk and 697 ± 69 kg body weight, six cows were fitted with a rumen cannula, and three were non-cannulated). Two groups of cows were randomly assigned to each of the dietary treatments in a crossover design: control (without FETR supplementation) and supplemented [with 0.75 mL of FETR·kg−1 dry matter (DM) of the diet based on our previous study]. The application of FETR tended to decrease the DM intake compared with control. There were no effects of FETR (P > 0. 10) on omasal nutrient flow and digestibility, rumen fermentation characteristics, and rumen pH profile. In conclusion, this study lacks evidence that the fibrolytic enzyme (at a level of 0.75 mL of FETR·kg−1 DM) can affect nutrient digestibility, ruminal fermentation, and the performance of early-lactation cows. Further study with larger animal trials are needed.

Evaluation of rumen protective effectiveness of L-carnitine, in vitro and in vivo

This study aimed to evaluate the rumen protective effectiveness of L-carnitine through in vitro tests, rumen degradation tests and in vivo tests. Twelve rumen-fistulated crossbred rams with similar body weights of 55±3.6 kg and ages of 3±0.2 years old were divided into three treatment groups in a 3×3 Latin square design, G1 (basal diet with no additives), G2 (unprotected L-carnitine) or G3 (rumen-protected L-carnitine). Ruminal fluid and blood samples were collected before morning feeding on the last day of each experimental period (21 d). The percentage of L-carnitine remaining in the simulated rumen and abomasum and rumen increased with the increase in the wall material ratio (P< 0.05). L-carnitine supplementation decreased the plasma urea nitrogen concentration of the sheep (P< 0.05). G3 resulted in higher GSH-Px and SOD activities as well as T-AOC and lower MDA concentrations in plasma than G1, and the difference was significant among the groups (P< 0.01). Thus, L-carnitine in the rumen could be protected by encapsulation for a certain time. Unprotected and rumen-protected L-carnitine supplementation effectively enhanced the antioxidant capacity of sheep, and the antioxidant capacity of sheep supplemented with rumen-protected L-carnitine was higher than that of sheep supplemented with unprotected L-carnitine.

Effects of dietary levels of calcium, phosphorus, and 1-alpha-hydroxycholecalciferol on digestibility, retention of calcium and phosphorus, and concentration of metabolizable energy in diets fed to sows in late-gestation

The apparent total tract digestibility and retention of calcium (Ca) and phosphorus (P) and concentrations of digestible energy and metabolizable energy in diets fed to late-gestating sows were not affected by Ca and P levels, but they were increased by dietary supplementation with 1-alpha-hydroxycholecalciferol. There was no interaction between dietary Ca and P and supplementation with 1-alpha-hydroxycholecalciferol.