Polymorphisms at Candidate Genes for Fat Content and Fatty Acids Composition: Effects on Sheep Milk Production and Fatty Acid Profile Using Two Dietary Supplementations

The nutritional value of sheep's milk and its derivatives is influenced by the lipid fraction, which is affected by diet and genetics. This study aimed to explore the genetic variations in the DGAT1 and SCD genes and assessed the impact of the DGAT1 genotype on milk quality in Valle del Belìce sheep, considering diet supplementation with carob pulp and barley grain. Among the potentially polymorphic sites, only DGAT1 g.127 C > A and SCD g.87 C > A showed variability. The DGAT1 genotype did not significantly impact milk yield and composition, except for higher urea content in the CA genotypes than in the CC ones. Carob pulp increased the milk fat content compared to barley grain. Genetic variation in DGAT1 was associated with changes in the milk fatty acid profile; specifically, the CA genotype exhibited higher levels of short-chain fatty acids and lower levels of polyunsaturated fatty acids compared to the CC genotype. Carob pulp supplementation increased saturated fatty acids and reduced unsaturated fractions, leading to milk with higher atherogenic and thrombogenic indices. No significant interaction was found between genotype and diet. This study provides insights into the genetic and dietary factors influencing sheep's milk composition. Further research is needed to understand the impact of these genetic variations on milk production and composition, as well as to determine optimal levels of carob pulp for improving fat percentage and promoting sustainable sheep breeding practices.

Post-anthesis thermal stress induces differential accumulation of bioactive compounds in field-grown barley

BACKGROUND

Barley (Hordeum vulgare L.) is a healthy grain because of its high content of dietary fibre and phenolic compounds. It faces periods of high temperature during grain filling, frequently reducing grain weight. Heat stress may also affect some of the bioactive compounds present in the grain. To produce quality grains that provide nutritional and health benefits, it is important to understand the effect of environmental stresses on the quantity and quality of bioactive compounds.

RESULTS

We have studied the effect of post-anthesis thermal stress on barley bioactive compounds and antioxidant capacity under Mediterranean field conditions during two consecutive growing seasons in four barley genotypes. Thermal stress affected grain weight and size and changed the relative composition of bioactive compounds. The relationship between heat stress and grain β-glucans and arabinoxylans content was indirect, as the resulting increases in concentrations were due to the lower grain weight under stress. Conversely, heat stress had a significant direct impact on some phenolic compounds, increasing their concentrations differentially across genotypes, which contributed to an improvement in antioxidant capacity of up to 30%.

CONCLUSION

Post-anthesis thermal stress had a significant effect on β-glucans, arabinoxylans, phenolic compound concentration and antioxidant capacity of barley grains. Final grain quality could, at least partially, be controlled in order to increase the bioactive concentrations in the barley grain, by cultivation in growing areas prone to heat stress. Late sowings or late flowering genotypes could also be considered, should a premium be implemented to compensate for lower yields. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Effect of feeding acidified or fermented barley using Limosilactobacillus reuteri with or without supplemental phytase on diet nutrient digestibility in growing pigs

Fermentation of cereal grains may degrade myo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate) (InsP6) thereby increasing nutrient digestibility. Effects of chemical acidification or fermentation with Limosilactobacillus (L.) reuteri with or without phytase of high β-glucan hull-less barley grain on apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of nutrients and gross energy (GE), standardized ileal digestibility (SID) of crude protein (CP) and amino acids (AAs), and standardized total tract digestibility (STTD) of P were assessed in growing pigs. Pigs were fed four mash barley-based diets balanced for water content: 1) unfermented barley (Control); 2) chemically acidified barley (ACD) with lactic acid and acidic acid (0.019 L/kg barley grain at a ratio of 4:1 [vol/vol]); 3) barley fermented with L. reuteri TMW 1.656 (Fermented without phytase); and 4) barley fermented with L. reuteri TMW 1.656 and phytase (Fermented with phytase; 500 FYT/kg barley grain). The acidification and fermentation treatments occurred for 24 h at 37 °C in a water bath. The four diets were fed to eight ileal-cannulated barrows (initial body weight [BW], 17.4 kg) for four 11-d periods in a double 4 × 4 Latin square. Barley grain InsP6 content of Control, ACD, Fermented without phytase, or Fermented with phytase was 1.12%, 0.59%, 0.52% dry matter (DM), or not detectable, respectively. Diet ATTD of DM, CP, Ca, and GE, digestible energy (DE), predicted net energy (NE) value, and urinary excretion of P were greater (P < 0.05) for ACD than Control. Diet ATTD of DM, CP, Ca, GE, DE and predicted NE value, urinary excretion of P was greater (P < 0.05), and diet AID of Ca and ATTD and STTD of P tended to be greater (P < 0.10) for Fermented without phytase than Control. Diet ATTD of GE was lower (P < 0.05) and diet ATTD and STTD of P, AID and ATTD of Ca was greater (P < 0.05) for Fermented with phytase than Fermented without phytase. Acidification or fermentation with/without phytase did not affect diet SID of CP and AA. In conclusion, ACD or Fermented without phytase partially degraded InsP6 in barley grain and increased diet ATTD of DM, CP, and GE, but not SID of CP and most AA in growing pigs. Fermentation with phytase entirely degraded InsP6 in barley grain and maximized P and Ca digestibility, thereby reducing the need to provide inorganic dietary P to meet P requirements of growing pigs.

Dry matter intake, digestibility, nitrogen utilization and fermentation characteristics of sheep fed Atriplex hay-based diet supplemented with discarded dates as a replacement for barley grain

This experiment aimed to investigate the effects of substituting barley grain with discarded dates on intake and digestibility, nitrogen (N) utilization and fermentation characteristics of sheep fed Atriplex hay-based diets. Four Barki sheep (50.9 ± 2.93 kg of body weight (BW)) fitted with rumen cannula were used in a 4 × 4 Latin Square design with 23-day periods. Four isonitrogenous (~140 g crude protein (CP)/kg of dry matter (DM)) experimental diets were formulated with Atriplex hay, and dietary sugar content was increased by replacing barley grain with discarded dates (the proportions of discarded dates in the diet were 0, 93, 187 and 280 g/kg DM). Nutrient intakes were not influenced by diet. Organic matter, CP and neutral detergent fibre digestibility increased (p < 0.05) linearly and DM digestibility tended to increase with increased dates inclusion. Ruminal pH and molar proportion of butyrate increased (p < 0.05) linearly with increasing levels of dates inclusion, whereas ruminal ammonia-N decreased (p < 0.05) linearly. Total volatile fatty acid concentration was unaffected. Microbial protein synthesis (MCP) increased linearly and efficiency of microbial protein synthesis tended to increase as discarded dates increased. Total N intake was not affected by diets whereas, urinary N, urea-N and total N execrations linearly decreased (p < 0.05) with higher amounts of dates in the diets. Blood urea-N tended to decrease with increasing levels of dates. It could be concluded that replacing 100% barley grain with discarded dates as a source of soluble carbohydrates can enhance the utilization of N in Atriplex hay-based diet and consequently improve digestibility and MCP.

Microbial fermentation of starch- or fibre-rich feeds added with dry or pre-activated Saccharomyces cerevisiae studied in vitro under conditions simulating high-concentrate feeding for ruminants

BACKGROUND

To study if the effect on fermentation of yeasts added in ruminant diets can be improved, the effect of adding dry (DY) or pre-activated (AY) Saccharomyces cerevisiae, compared with unsupplemented rumen fluid (CT), on barley grain or sugar beet pulp was evaluated under in vitro high-concentrate fermentative conditions. Yeasts were pre-activated by culturing aerobically at 30 °C for 24 h.

RESULTS

In Experiment 1, AY showed a higher concentration than DY at 6 h incubation (6.83 versus 5.76 log cfu mL^-1 ; P = 0.007), differences disappearing at 12 h. This was supported by higher gas production with AY, especially on sugar beet pulp. In Experiment 2, incubation pH was 6.24 and 6.31 respectively for barley and sugar beet pulp at 8 h (P < 0.05), but no effect was recorded at 24 h (6.00 and 5.96; P > 0.05). With sugar beet pulp, gas production promoted by AY was the highest (P < 0.05) in the first 8 h of incubation. However, differences with barley were lower and only detected between AY and CT at 12 h (P < 0.05). Total volatile fatty acids (VFAs) concentration at 8 h followed the same trend, but no differences were detected on molar VFAs profile or lactate concentration. Microbial diversity was more affected by the incubation series than by experimental treatments, and inocula including yeasts (AY, DY) did not differ from unsupplemented rumen liquid.

CONCLUSIONS

When pre-activated, the concentration of S. cerevisiae was initially higher and resulted in higher gas volumes, and more on a fibrous (sugar beet pulp) than a starchy (barley) substrate. The response is apparently quantitative, since no major changes were detected on biodiversity or fermentation profile. © 2020 Society of Chemical Industry.

The inter-relationship between processing-induced molecular structure features and metabolic and digestive characteristics in hulled and hulless barley (Hordeum vulgare) grains with altered carbohydrate traits

BACKGROUND

The present study aimed to determine the microwave irradiation (MIR)-induced changes in protein molecular structures in barley (Hordeum vulgare) grains in relation to the truly absorbable protein nutrient supply to ruminant livestock systems. Samples from hulled and hulless cultivars of barley, harvested in consecutive years from four replicate plots, were evaluated. The samples were either kept raw or were irradiated with microwaves for 3 min (MIR3) or 5 min (MIR5). The truly absorbable protein nutrient supply to ruminant livestock systems was evaluated using the DVE/OEB system (DVE, truly absorbed protein in the small intestine; OEB, degraded protein balance). Molecular structure changes as a result of processing were revealed by vibrational molecular spectroscopy in the mid-infrared electromagnetic radiation region.

RESULTS

Compared to the raw samples, MIR processing decreased (P < 0.05) the truly absorbable microbial crude protein and increased (P < 0.05) the truly absorbable rumen undegraded protein and endogenous protein supply without affecting the total truly absorbed protein supply to the small intestine (DVE) and degraded protein balance (OEB) in ruminant livestock systems. Changes in protein molecular structure (spectral intensities) were highly correlated with the changes in the truly absorbed protein nutrient supply to ruminant livestock systems.

CONCLUSION

The results of the present study show that the changes in protein molecular structure as a result of MIR feed processing were associated with the truly absorbed protein supply to ruminant livestock systems. © 2016 Society of Chemical Industry.

Metabolite profiling of barley grain subjected to induced drought stress: responses of free amino acids in differently adapted cultivars

To investigate cultivar-specific metabolite changes upon drought stress in barley grain, differently adapted cultivars were field-grown under drought conditions using a rain-out shelter and under normal weather conditions (2010-2012). The grain was subjected to a gas chromatography-mass spectrometry-based metabolite profiling approach allowing the analyses of a broad spectrum of lipophilic and hydrophilic low molecular weight constituents. Multi- and univariate analyses demonstrated that there are grain metabolites which were significantly changed upon drought stress, either decreased or increased in all cultivars. On the other hand, for proteinogenic free amino acids increased concentrations were consistently observed in all seasons only in cultivars for which no drought resistance/tolerance had been described. Consistent decreases were seen only in the group of stress tolerant/resistant cultivars. These cultivar-specific correlations were particularly pronounced for branched-chain amino acids. The results indicate that free amino acids may serve as potential markers for cultivars differently adapted to drought stress.

Thermodormancy and ABA metabolism in barley grains

Incubation of barley primary dormant grains at 30°C, a temperature at which they cannot germinate results in a reinforcement of their sensitivity to temperature, and in particular in a loss of their ability to germinate at 15–20°C. Incubation of the grains at 30°C in the presence of GA₃ (1 mM) or of isolated embryos prevents this induction of secondary dormancy. In such a condition, embryo ABA content was lower than that measured in embryos of seeds incubated at 30°C on water. Expression of genes involved in ABA metabolism (HvABA8′OH1, HvNCED1 and HvNCED2) was studied in isolated embryos incubated on water and in the presence of GA₃ (1 mM). Expression of HvABA8′OH1, HvNCED1 and HvNCED2 was discussed in relation with ABA content and germination ability at 30°C.

Colonization of Barley Grain by Penicillium verrucosum and Ochratoxin A Formation in the Presence of Competing Fungi

Colonization of barley grain by Penicillium verrucosum and the formation of ochratoxin A were studied, both in pure culture and when paired with Aspergillus flavus , Fusarium sporotrichioides , and Hyphopichia burtonii , at 20° and 30°C and at 0.97, 0.95 and 0.90 a_w over a 3-week period. Grain colonization was assessed on the basis of visible molding, seed infection, and numbers of CFU and by observing hyphal extension on the grain surface by scanning electron microscopy. Ochratoxin A concentrations were assayed by enzyme-linked immunosorbent assay using a monoclonal antibody. Germination of P. verrucosum spores was unaffected by the presence of other species. However, seed infection under most conditions was markedly decreased, relative to pure culture, by the presence of A. flavus and H. burtonii , but only slightly by F. sporotrichioides . The number of CFU of P. verrucosum was only slightly decreased in the presence of other species under most conditions. Generally, production of ochratoxin A by P. verrucosum was inhibited, sometimes significantly, in the presence of A. flavus and H. burtonii , but was changed only slightly by the presence of F. sporotrichioides . There was occasionally temporary enhancement in ochratoxin A production with all species during the 3-week incubation period.