The effect of the heat processing of soybean seed on the metabolism of its selenium in lambs

Rumen fermentation of meal-fed sheep in response to diets formulated to vary in fiber and protein degradability

The concentration of volatile fatty acid (VFA) provides an imprecise view of VFA dynamics due to the confounding effects of fluid pool size and dynamics. Determination of VFA flux using isotope is expensive and a complex methodology. Therefore, a rapid and affordable approach to explore VFA dynamics may allow comprehensive characterization of VFA availability. The objective of this study was to explore the use of VFA dynamics generated by meal feeding to derive time-series rates of VFA apparent appearance and disappearance driven by different protein and fiber sources. Six ruminally cannulated wethers were fed diets containing timothy hay or beet pulp (TH and BP) and soybean meal (SBM) or heated soybean meal (HSBM). Diets were, TH + HSBM; TH + SBM; BP + HSBM; and BP + SBM and the experimental design was a partially replicated 4 × 4 Latin Square. Concentrations of VFA and polyethylene glycol (PEG) in rumen fluid samples were estimated. Concentrations of PEG were used to estimate fluid passage and volume to calculate VFA mass, and fluid-mediated exit. Maximum apparent appearance rate (mmol/h), the rate of apparent appearance decline (mmol/mmol/h), mean apparent appearance flux (mmol/h), mean apparent disappearance (mmol/h), and apparent disappearance rate (mmol/mmol/h) were estimated by deriving a 1 pool model for each VFA on a mass basis where appearance was assumed to follow an exponential decay pattern and disappearance followed mass-action kinetics. Statistical analyses were conducted using a linear mixed effect regression with fixed effects for fiber source, protein source, and their interaction, as well as random effects for animal and period. Rumen fluid volume (L) was greater in HSBM diets (P = 0.033) and fluid passage (%/h) was greater in SBM diets (P = 0.048). Concentrations (higher acetate and butyrate, P = 0.002 and 0.004, respectively) and molar proportions (higher valerate, P = 0.035) of VFA were affected only by fiber source; however, protein source and fiber source interacted to significantly influence apparent appearance rates and absorption rates of many major VFA. On a flux basis, HSBM supported significantly elevated mean disappearance of propionate (P = 0.033). This data demonstrates that time-series evaluation of fermentation dynamics, including fluid dynamics and VFA concentrations can be used to estimate apparent appearance and disappearance of VFA. Although further work is needed to confirm the alignment of these estimates with measurements of VFA supplies to the animal, this modeling approach may provide a simpler way to better understand the kinetics of rumen.

Effects of Selenium Supplementation on Rumen Microbiota, Rumen Fermentation, and Apparent Nutrient Digestibility of Ruminant Animals: A Review

Enzymes excreted by rumen microbiome facilitate the conversion of ingested plant materials into major nutrients (e.g., volatile fatty acids (VFA) and microbial proteins) required for animal growth. Diet, animal age, and health affect the structure of the rumen microbial community. Pathogenic organisms in the rumen negatively affect fermentation processes in favor of energy loss and animal deprivation of nutrients in ingested feed. Drawing from the ban on antibiotic use during the last decade, the livestock industry has been focused on increasing rumen microbial nutrient supply to ruminants through the use of natural supplements that are capable of promoting the activity of beneficial rumen microflora. Selenium (Se) is a trace mineral commonly used as a supplement to regulate animal metabolism. However, a clear understanding of its effects on rumen microbial composition and rumen fermentation is not available. This review summarized the available literature for the effects of Se on specific rumen microorganisms along with consequences for rumen fermentation and digestibility. Some positive effects on total VFA, the molar proportion of propionate, acetate to propionate ratio, ruminal NH3-N, pH, enzymatic activity, ruminal microbiome composition, and digestibility were recorded. Because Se nanoparticles (SeNPs) were more effective than other forms of Se, more studies are needed to compare the effectiveness of synthetic SeNPs and lactic acid bacteria enriched with sodium selenite as a biological source of SeNPs and probiotics. Future studies also need to evaluate the effect of dietary Se on methane emissions.

The Efficacy of a Long-Acting Injectable Selenium Preparation Administered to Pregnant Ewes and Lambs

Simple Summary

Lack of selenium (Se) is a global problem that leads to increased exposure of animals to various diseases, as well as a reduction in productive and reproductive performance. Mineral supplementation can improve the immune system and could therefore be of assistance for lambs. We studied the effects of injectable supplementation with selenium. Supplementation of the Se lead to improved immune status, blood parameters, body weights, and average daily gain of lambs.

Abstract

The aim of this study was to evaluate the effects of a long-acting selenium (Se) preparation administered to sheep. The experiment was conducted on 30 dams and 36 lambs divided into three equal groups of 10 dams and 12 lambs each: Control—C, and two experimental groups—E (Se administered to pregnant ewes) and EI (Se administered directly to lambs after the colostral period). The Se preparation (Barium Selenate Injection, BVP Animal Care, 50 mg/mL) was administered by injection at 1 mL/50 kg (1 mg Se/kg) body weight (BW) to group E ewes in the third month of pregnancy (between 70 and 90 days) and to group EI lambs between 4 and 7 days of age. The following parameters were determined: Se concentration in the blood of ewes, milk yield, milk composition, Se concentration in milk; hematological, biochemical, and immunological parameters and Se concentration in the blood of lambs; growth rate and in vivo measurements of lean meat and fat content in lambs. Barium selenate significantly improved the Se status of dams and lambs, regardless of whether it was administered to pregnant ewes or directly to lambs in the first week of their life. The milk of ewes receiving the Se preparation was characterized by higher concentrations of fat and dry matter. The Se preparation induced significant changes in immunological parameters, thus enhancing defense mechanisms in lambs. The Se preparation exerted more stimulatory effects on humoral and cellular immune responses when administered directly to lambs after the colostral period (group EI) than to pregnant ewes (group E). The results of this study indicate that the long-acting Se preparation delivers benefits to sheep by boosting their immunity and, therefore, improving performance.

Producing milk with uniform high selenium concentrations on commercial dairy farms

Six herds on five commercial dairy farms were involved in the production of high selenium (Se) milk. The farms had a range of herd sizes, herd structures, feeding systems and milk production per cow. On all farms, pelleted concentrate supplements containing Se yeast were fed twice daily in the dairy for 16 days. The objectives were to: (1) produce milk with Se concentrations exceeding 225 μg/kg on the five farms for pilot-scale production of a high protein milk powder; (2) validate a predictive relationship between Se intake and milk Se concentration developed in research; and (3) examine the time taken from the introduction of Se yeast to steady-state concentrations of Se in milk under a range of commercial farming conditions. We hypothesised that the relationship between Se intake and its concentration in milk found in research would apply on commercial farms. Daily Se intake, which was primarily from Se yeast in the pelleted concentrates, varied from 35 to 51 mg Se/cow. Grazed pasture and conserved forage contributed less than 1 mg Se/cow on all farms. The time taken from the introduction of pellets containing Se yeast to steady-state milk Se concentrations was 4–7 days. The steady-state Se concentrations in milk varied from 166 to 247 µg/kg, but these concentrations were only 55–72% of predicted values. All the milk produced from the five farms on the last 2 days of feeding of Se-enriched pellets was used to produce a milk protein concentrate with a Se concentration of 5.4 mg/kg. Factors that might have affected Se incorporation into milk and the implications of these results for commercial production of high Se milk or milk products are discussed.

Effect of pelleting of concentrates on milk and blood selenium concentrations in lactating dairy cows when selenised yeast is included in the diet

An experiment using 12 multiparous Holstein–Friesian cows was undertaken for 3 weeks in September–October 2008 to determine milk and blood selenium (Se) concentrations (surrogates for bioavailability) when Se-yeast was incorporated into pellets relative to providing unprocessed Se-yeast. The Se in the Se-yeast is principally in the form of seleno-methionine. Since the bioavailability of protein can be reduced by heat processing, it was hypothesised that the temperature and/or pressure conditions associated with commercial pelleting of concentrates would adversely influence the Se concentrations in milk and blood by reducing the bioavailability of Se in the animal compared with Se-yeast that had not been subjected to pelleting. The results clearly showed that pelleting conditions had no effect on concentrations of either milk or blood Se, thereby indicating that pelleting did not have an impact on the bioavailability of the Se in the animal.