A suitable enzymatic method for starch quantification in different organic matrices

Predicting ruminal degradability and chemical composition of corn silage using near-infrared spectroscopy and multivariate regression

The aim of this study was to develop and validate regression models to predict the chemical composition and ruminal degradation parameters of corn silage by near-infrared spectroscopy (NIR). Ninety-four samples were used to develop and validate the models to predict corn silage composition. A subset of 23 samples was used to develop and validate models to predict ruminal degradation parameters of corn silage. Wet chemistry methods were used to determine the composition values and ruminal degradation parameters of the corn silage samples. The dried and ground samples had their NIR spectra scanned using a poliSPECNIR 900-1700 model NIR sprectrophotometer (ITPhotonics S.r.l, Breganze, IT.). The models were developed using regression by partial least squares (PLS), and the ordered predictor selection (OPS) method was used. In general, the regression models obtained to predict the corn silage composition (P>0.05), except the model for organic matter (OM), adequately estimated the studied properties. It was not possible to develop prediction models for the potentially degradable fraction in the rumen of OM and crude protein and the degradation rate of OM. The regression models that could be obtained to predict the ruminal degradation parameters showed correlation coefficient of calibration between 0.530 and 0.985. The regression models developed to predict CS composition accurately estimated the CS composition, except the model for OM. The NIR has potential to be used by nutritionists as a rapid prediction tool for ruminal degradation parameters in the field.

Thermoregulation and Performance of Dairy Cows Subjected to Different Evaporative Cooling Regimens, with or without Pepper Extract Supplementation

The objective of this study was to evaluate whether there is an interaction between pepper extract (PE) supplementation and evaporative cooling regimens on the performance, thermal comfort, and metabolism of lactating cows. The experiment was designed as a double 4 × 4 Latin square using eight multiparous Holstein cows (days in milk 147 ± 43.8 days). Treatments were a 2 × 2 factorial arrangement; two evaporative cooling regimens [sprinkler cycles of 30 s on and 4.5 min off (R5) and 30 s on and 9.5 min off (R10)] were combined with no inclusion of pepper extract (CT) or 800 mg/cow daily of PE. The inclusion of PE allowed a greater reduction in the surface temperature of the coat, and the cows remained for longer periods in the feeding area. There was an interaction between the use of PE and the climate regimen for surface temperature, which was lower for PER5. Cows experiencing greater intermittency in the spraying cycles (R10) spent 35% more time at the feeding area. A significant interaction was observed for milk production, with greater production for CTR5 compared to the other treatments. The feed efficiency for R5 was higher than that for R10. The R5 treatment combined with PE reduced water intake. There was no significant difference in serum parameters other than gamma-glutamyl transferase, with an interaction between treatments and greater activity for PER10, and total protein and albumin, which had cooling effects that were higher for R10. The two factors tested interfered in different and dissociated ways. The evaporative cooling strategies were effective, and the R5 treatment resulted in higher feed efficiency and milk production. The inclusion of PE enhanced heat reduction in cows when they were subjected to a cooling regime.

Feed intake, nutrient digestibility, and selected rumen parameters in feedlot bulls fed diets with different feed additives

An experiment was conducted to evaluate the feed intake, nutrient digestibility and selected rumen parameters in feedlot bulls fed diets containing different feed additives. Six rumen-cannulated Nellore bulls (age = 8 ± 1.0 months; initial BW = 225 ± 13.2 kg) were distributed in a 6 × 6 Latin square design. Six experimental diets based on 30% corn silage and 70% concentrate on a dry matter (DM) basis were evaluated. Diets differed in feed additive on a DM basis, as follows: 1.4% bicarbonate and magnesium oxide in 3:1 ratio (BOX); 36 ppm lasalocid sodium (LAS); 30 ppm monensin sodium (MON); 25 ppm virginiamycin (VIR); 30 ppm monensin sodium plus 25 ppm virginiamycin (MV); and 3.15% commercial mineral supplement containing D-limonene and exogenous α-amylase (EOA). The experiment lasted 144 d, with six periods of 24 d. Each period consisted of 14 d for dietary adaptation, 3 d for feces and urine collection, and 7 d for omasal and ruminal digesta collection. Bulls fed the BOX diet showed greater (P < 0.05) intake of DM, organic matter (OM), neutral detergent fiber (apNDF), crude protein (CP), and starch compared to the other diets. Diets with LAS, MON, VIR, MV, or EOA did not influence (P > 0.05) the DM, OM, apNDF, CP, or starch intake of feedlot bulls. Bulls fed the EOA diet showed greater (trend; P = 0.09) ruminal digestibility of starch compared to the other diets. The feed additives did not affect (P > 0.05) the intestinal or total tract digestibility of starch, rumen pH, microbial efficiency, total rumen fluid, dilution rate, rate of intake, rate of degradation, or passage rate of the DM, OM, apNDF, and starch. In conclusion, LAS, MON, VIR, MV, and EOA diets reduced nutrient intake compared to BOX. Although all feed additives presented similar effects on rumen pH, temperature, and kinetics the presence of exogenous α-amylase in the EOA diet may increase ruminal starch digestibility and apparent total tract digestibility of DM and OM.

Reconstituted and ensiled corn or sorghum grain: Impacts on dietary nitrogen fractions, intake, and digestion sites in young Nellore bulls

Two experiments were conducted: (1) to evaluate the effect of ensiling time and grain source on dietary nitrogen fractions; and (2) to verify the influence of concentrate level, processing method and grain source on intake, microbial efficiency, and digestibility by young Nellore bulls. In Experiment 1, corn and sorghum grains were milled, reconstituted to 35% moisture, and ensiled in a bag silo for 10 different times. There were three replications per ensiling time and grain source. Samples from each replication were analyzed in triplicate for total nitrogen (N), non-protein nitrogen (NPN), soluble N, insoluble N, and neutral detergent insoluble nitrogen (NDIN). In Experiment 2, five Nellore bulls were used in a 5 × 5 Latin square design. Four diets were comprised of 28.4% corn silage, 10.7% supplement, and 60.9% dry ground corn, dry ground sorghum, reconstituted and ensiled corn, or reconstituted and ensiled ground sorghum. An additional diet comprised of 45% corn silage, 10.7% supplement, and 44.3% dry ground corn (Roughage+) was used. Each experimental period lasted 22 days, with an adaptation period of 14 days followed by 5 days of total feces and urine collection and 3 days of collecting omasal samples. Data were analyzed using the MIXED procedure of SAS 9.4. The reconstitution and ensiling process reduced (P < 0.05) the insoluble N fraction, increased (P < 0.05) non-protein nitrogen of corn and sorghum grains, tended (P = 0.052) to increase microbial efficiency, and increased (P < 0.05) intestinal and total digestion of dry matter (DM), organic matter (OM), crude protein (CP), and starch. The concentrate level affected neither (P > 0.05) DM intake nor rumen pH. On the other hand, bulls fed diets based on 72% concentrate showed greater (P < 0.05) DM, OM, and CP digestibility compared with those fed a diet based on 55% concentrate. In addition, animals fed diets based on corn grains (both reconstituted and ensiled or dry) presented greater (P < 0.05) intestinal and total starch digestion compared to those fed sorghum grain. Therefore, the reconstitution process can reduce the insoluble N fraction and increase nutrient availability.