Use of biostimulants in elephant grass cv. Napier

This study was developed to examine the growth, yield, chemical composition and in situ degradability of elephant grass cv. Napier (Pennisetum purpureum). Five spraying protocols with biostimulants were tested, namely, Control - no application; 1BR - bioregulator at seven days; 2BR - bioregulator at seven days + bioregulator and foliar fertilization at 20 days; 2BR2 - bioregulator at seven days + bioregulator and foliar fertilization at 20 days + ethylene inhibitor at 30 days; and 3BR - bioregulator at seven days + bioregulator and foliar fertilization at 20 days + ethylene inhibitor and bioregulator at 30 days. The grass was cut evenly at a height of 15 cm and harvested at 70 days of regrowth. The experimental area was divided into two blocks according to the slope. Ninety plots were used, totaling an area of 4,608 m2. Each plot was composed of four 4-m rows spaced 80 cm apart. Chemical composition, morphological traits and forage digestibility data were evaluated. The 3BR protocol, with more bioregulator-based applications, resulted in higher canopy (9.78%) and stem (9.58%) compared with control group. The 2BR and 2BR2 treatments provided a 6.5% higher stem than control treatment. The improvement in the nutritional value of Pennisetum purpureum cv. Napier was due to the 17.55% increase in crude protein (CP) content provided by protocol 3BR relative to control group. Treatments 2BR2 and 3BR improved the effective degradability of dry matter (DM). The application of biostimulant protocols increased the potential degradability of neutral detergent fiber (NDF) (+4.1%), with the greatest response seen in treatment 2BR2 in comparison with control treatment. Biostimulant protocols increase the canopy and stem heights and CP content. The application of a bioregulator associated with foliar fertilization and ethylene inhibitor improves the effective degradability of DM and NDF and the potential degradability of NDF in Pennisetum purpureum cv. Napier harvested at 70 days of regrowth.

Protein-energy supplementation on productive and nutritional performance of grazing beef heifers

This study was conducted with the aim of evaluating the effect of protein-energy supplementation on productive performance, intake, digestibility, and microbial protein synthesis in heifers fed tropical forage. Twelve Nellore heifers at 11 months of age, with a mean initial body weight of 248.8 ± 11.40 kg were used. The animals were distributed in a completely randomized design with two treatments and six replicates. The treatments evaluated were: control (without supplementation); and supplementation in the amount of 1.5 kg animal-1 day-1. Forage samples were collected to evaluate the chemical composition and the total availability of dry matter of the pasture consumed by the animals. To evaluate the intake and forage digestibility, a trial was performed using internal and external markers. In this study no effect of supplementation was observed on the intakes of dry matter (DM), organic matter (OM), forage DM, or neutral detergent fiber corrected for ash and protein (NDFap; P > 0.10). However, supplementation increased (P < 0.01) the intakes of crude protein (CP), ether extract (EE), and non-fibrous carbohydrates (NFC). Additionally, an upward trend (P=0.076) was observed in the intake of digested OM (DOM) with supplementation. On the other hand, supplementation increased (P < 0.01) the digestibility coefficients of OM, CP, EE, and NFC, although supplementation did not affect the ruminal synthesis of nitrogen compounds (MICN), efficiency of protein microbial synthesis (EMS), relative microbial nitrogen (RMICN) or urine urea nitrogen (UUN) excretion (P > 0.57). Lastly, supplementation increased (P=0.050) the average daily gain of the animals, although no effect (P > 0.10) was observed on their final body weight. These results suggested that protein-energy supplementation improves the productive performance and nutritional characteristics of grazing beef heifers.

Seasonal Differences in Structural and Genetic Control of Digestibility in Perennial Ryegrass

Perennial ryegrass is an important forage crop in dairy farming, either for grazing or haying purposes. To further optimise the forage use, this study focused on understanding forage digestibility in the two most important cuts of perennial ryegrass, the spring cut at heading and the autumn cut. In a highly diverse collection of 592 Lolium perenne genotypes, the organic matter digestibility (OMD) and underlying traits such as cell wall digestibility (NDFD) and cell wall components (cellulose, hemicellulose, and lignin) were investigated for 2 years. A high genotype × season interaction was found for OMD and NDFD, indicating differences in genetic control of these forage quality traits in spring versus autumn. OMD could be explained by both the quantity of cell wall content (NDF) and the quality of the cell wall content (NDFD). The variability in NDFD in spring was mainly explained by differences in hemicellulose. A 1% increase of the hemicellulose content in the cell wall (HC.NDF) resulted in an increase of 0.81% of NDFD. In autumn, it was mainly explained by the lignin content in the cell wall (ADL.NDF). A 0.1% decrease of ADL.NDF resulted in an increase of 0.41% of NDFD. The seasonal traits were highly heritable and showed a higher variation in autumn versus spring, indicating the potential to select for forage quality in the autumn cut. In a candidate gene association mapping approach, in which 503 genes involved in cell wall biogenesis, plant architecture, and phytohormone biosynthesis and signalling, identified significant quantitative trait loci (QTLs) which could explain from 29 to 52% of the phenotypic variance in the forage quality traits OMD and NDFD, with small effects of each marker taken individually (ranging from 1 to 7%). No identical QTLs were identified between seasons, but within a season, some QTLs were in common between digestibility traits and cell wall composition traits confirming the importance of hemicellulose concentration for spring digestibility and lignin concentration in NDF for autumn digestibility.

Effect of protein and glucogenic precursor supplementation on forage digestibility, serum metabolites, energy utilization, and rumen parameters in sheep

Supplementation of glucogenic precursors in roughage diets may increase production responses due to improved efficiencies of nutrient utilization. Therefore, the objective of this study was to determine the effect of source of supplemental glucogenic potential (GP) on forage digestibility, serum metabolites, energy utilization, and rumen parameters of growing wethers consuming a roughage diet (8.8% crude protein, 71.4% ash-free neutral detergent fiber). Crossbred wethers (49.1 ± 4.7 kg initial BW; n = 16) were utilized in a 4 × 4 replicated Latin Square design with four periods of 21 d. Supplements were designed to supplement increasing amount of GP: (1) no supplementation (CON; 0 g), (2) 40 g of calcium propionate (CAP; 30 g of GP), (3) 70 g of blood meal + 100 g of feather meal (BF; 40 g of GP), or (4) combination of CAP and BF (COMBO; 70 g of GP). Total fecal and urine collection was conducted from d 13 – 17 to calculate digestibility estimates and urinary losses. An acetate tolerance test was administered on d 17 to determine the effect of GP on acetate clearance. Blood samples were collected on d 19 and were analyzed for serum concentrations of glucose, urea N (SUN), non-esterified fatty acids, and amino acids. Rumen fluid was collected on d 21 to determine supplementation effects on ruminal volatile fatty acid (VFA) and ammonia concentrations. Wethers receiving BF and COMBO supplementation had greatest (P ≤ 0.01) DM and OM total tract digestibility. Supplementation did not affect (P ≥ 0.37) NDF digestibility or digestible energy. Urinary nitrogen excretion was greatest (P = 0.02) for BF and COMBO. Circulating serum essential amino acid concentration was increased (P &lt; 0.01) in BF and COMBO compared to CAP and CON. In addition, BF and COMBO had increased (P &lt; 0.01) SUN concentrations compared to CAP and CON. Acetate half-life was not affected (P = 0.39) by supplementation strategy. However, area under the curve (AUC) for acetate was decreased (P = 0.04) with supplementation of BF and COMBO compared to CON-fed wethers. Ruminal propionate concentration was increased (P ≤ 0.01) for wethers fed CAP and COMBO supplementation, which resulted in decreased (P ≤ 0.01) A:P ratio. Overall, these results indicate that the increased propionate supply by providing propionate salts did not result in a protein sparing impact or increased N retention.

Agronomic aspects, chemical composition and digestibility of forage from corn-crotalaria intercropping

The objective of this study was to evaluate the effect of different intercropping and spacing arrangements of corn (Zea mays L) and crotalaria (Crotalaria spp) on the agronomic characteristics, chemical composition and forage digestibility. The experiment was distributed in a randomized complete block design with a 2 × 2 + 1 factorial scheme. The treatments were two cultivation systems (corn + Crotalaria juncea (CCJ) intercropping, and corn + Crotalaria ochroleuca (CCO) intercropping), in two spacing arrangements (A1 (corn and crotalaria sown in the same row) and A2 (corn and crotalaria sown in alternate rows)) plus control (single corn monocropping (CSC)), with six replicates per treatment, for 2 years. Forage plants were harvested when the corn grain reached the doughy-farinaceous phenological stage. Forage mass (total and of each species), morphological composition, chemical composition and in vitro digestibility were evaluated. The forage accumulation was higher for the A1 spatial arrangement. In the second year, the highest total forage mass was verified in the CCO intercropping (11 140 kg/ha). The highest corn mass (9402 kg/ha) was observed for CSC. The highest crotalaria mass was observed in the CCJ intercropping in both years. Regarding the chemical composition, CCJ and CCO intercropping had the highest crude protein concentration. The lowest acid detergent fibre concentration was observed in CSC and CCO intercropping, directly reflecting the in vitro dry matter digestibility coefficients. It is concluded that C. ochroleuca, sown between corn rows, had higher forage accumulation and nutritive value among the treatments tested in this experiment.

Digestibility and rumen fermentation of a high forage diet pre-treated with a mixture of cellulase and xylanase enzymes

Forages play an important role in ruminant animal production worldwide. Unlocking the nutritional potential of poor-quality tropical forages with fibrolytic enzymes would improve forage digestibility and utilization. Using in vitro and in vivo methods this study investigated the effect of pre-treating Smutsfinger hay for 24 hours with a mixture of fibrolytic enzyme (100% cellulase; 75% cellulase: 25% xylanase; 50% cellulase: 50% xylanase; 25% cellulase: 75% xylanase; 100% xylanase and a control with no enzyme) on ruminal fermentation and digestibility of nutrients by sheep. For in vitro fermentation, dry matter, neutral detergent fibre (NDF) degradability and volatile fatty acids (VFA) were determined with standard procedures. The same treatments were used for an in vivo digestibility trial using Merino sheep in a 6 x 6 Latin square design. Feed intake and total tract digestibility were recorded. Rumen fluid samples were collected daily, preserved, and analysed for VFA. The addition of 100% cellulase enzyme to Smutsfinger hay in vitro increased (P <0.05) NDF degradability and gas production compared with the control and inclusion of 100% xylanase enzyme. Both 100% cellulase and xylanase enzymes significantly reduced in vitro end time fermentation pH. A 50:50 mixture of cellulase and xylanase plus enzyme in vivo, increased acetate, total VFA concentration, and higher NDF and ADF digestibility of the test feed compared with the control. Inclusion of a 50-75% mixture of cellulase and 50-25% xylanase enzymes treatment led to higher gas production and butyrate concentration, decreased ruminal pH and improved nutrient digestibility.

Biomass Yield and Nutritive Value of Rye (Secale cereale L.) and Wheat (Triticum aestivum L.) Forages While Grazed by Cattle

Management strategies that integrate crops and livestock may lengthen the productivity of seasonal pasture systems in agroecological zones with short growing seasons. The biomass yield and nutritive value of fall-planted rye (Secale cereale L.) and wheat (Triticum aestivum L.) forages were determined in an integrated crop–livestock system under rotational cattle (Bos taurus L.) grazing and organic conditions for seven weeks during the spring and summer in Minnesota, USA. Rye yielded greater forage biomass at the beginning of the grazing interval, while wheat yielded greater forage biomass in the latter part of the grazing interval. In general, wheat had greater crude protein and less neutral detergent fiber, compared to rye, throughout the grazing interval. The predicted total tract neutral detergent fiber digestibility of forages was ≥50 g 100 g−1 of neutral detergent fiber for at least the first four weeks of the grazing interval, indicating high forage digestibility in immature forages. Results from this study suggest that rye may provide more forage biomass for grazing earlier in the spring at the expense of lower nutritive quality, compared to wheat. Thus, the biomass yield and nutritional value of rye and wheat forages vary during the grazing interval, which informs producers of grazing schedule modifications in order to meet the nutritional demands of cattle.

Assessing the Potential of Diverse Forage Mixtures to Reduce Enteric Methane Emissions In Vitro

Methane emissions from ruminants are a major contributor to agricultural greenhouse gas emissions. Thus, eight different forage species were combined in binary mixtures with Lolium perenne in increasing proportions, in vitro, to determine their methane reduction potential in ruminants. Species were sampled in two consecutive years where possible. The aims were: a) to determine if mixtures with specific forages, particularly those rich in plant specialized metabolites (PSM), can reduce methane emissions compared to ryegrass monocultures, b) to identify whether there is a linear-dose effect relationship in methane emissions from the legume or herb addition, and c) whether these effects are maintained across sampling years. Results showed that all dicot species studied, including the non-tannin-containing species, reduced methane production. The tannin-rich species, Sanguisorba minor and Lotus pedunculatus, showed the greatest methane reduction potential of up to 33%. Due to concomitant reductions in the forage digestibility, Cichorium intybus yielded the lowest methane emissions per digestible forage unit. Contrary to total gas production, methane production was less predictable, with a tendency for the lowest methane production being obtained with a 67.5% share of the legume or herb partner species. Thus, linear increments in the partner species share did not result in linear changes in methane concentration. The methane reduction potential differed across sampling years, but the species ranking in methane concentration was stable.

Genetic Dissection for Maize Forage Digestibility Traits in a Multi-Parent Advanced Generation Intercross (MAGIC) Population

Forage feedstock is the greatest source of energy for livestock. Unfortunately, less than 50% of their fiber content is actually digested and assimilated by the ruminant animals. This recalcitrance is mainly due to the high concentration of plant cell wall material and to the limited digestion of the fiber by the microorganisms. A Genome-Wide Association Study (GWAS) was carried out in order to identify Single Nucleotide Polymorphisms (SNPs) associated with forage digestibility traits in a maize Multi-Parent Advanced Generation Intercross (MAGIC) population. We identified seven SNPs, corresponding to five Quantitative Trait Loci (QTL), associated to digestibility of the organic matter, 11 SNPs, clustered in eight QTLs, associated to Neutral Detergent Fiber (NDF) content and eight SNPs corresponding with four QTL associated with Acid Detergent Fiber (ADF). Candidate genes under the QTL for digestibility of the organic matter could be the ones involved in pectin degradation or phenylpropanoid pathway. Transcription factor genes were also proposed for the fiber QTL identified, in addition to genes induced by oxidative stress, or a gene involved in lignin modifications. Nevertheless, for the improvement of the traits under study, and based on the moderate heritability value and low percentage of the phenotypic variability explained by each QTL, a genomic selection strategy using markers evenly distributed across the whole genome is proposed.

Dynamic QTL analysis for developmental behavior of cell wall components and forage digestibility in maize (Zea mays L.)

Background Cell wall architecture plays a key role in stalk strength and forage digestibility. Lignin, cellulose and hemicellulose are the three main components of the plant cell wall and can impact stalk quality by affecting cell wall structure and strength. To explore cell wall development during secondary cell wall lignification in maize stalks, conventional and conditional genetic mappings was used to identify the dynamic quantitative trait locus (QTL) for cell wall components and digestibility traits in five growth stages after silking. Results Acid detergent lignin (ADL), cellulose (CEL), Acid detergent fiber (ADF), neutral detergent fiber (NDF), and in vitro dry matter digestibility (IVDMD) of stalk were evaluated in a maize recombinant inbred line (RIL) population. The cell wall components gradually increased in the 10–40 days after silking (DAS), reached a maximum at 30–40 DAS, and then steadily decreased. IVDMD decreased over the initial 40 DAS and then increased slightly. Seventy-two QTL were identified for five traits and each accounted for 3.48–24.04% of the phenotypic resistance variation. Twenty-six conditional QTL were detected using conditional QTL mapping. 22 out of 24 conditional QTL were found for stages III|II and V|IV. Six QTL hotspots were found localized in bins 1.08, 2.04, 2.07, 7.03, 8.05, and 9.03 in the maize genome. Conclusion The unconditional pleiotropic QTL in bins 1.08 and 8.05 were also associated with stalk strength. Furthermore, several pleiotropic QTL for cell wall and digestibility were found not associated with stalk strength. A simultaneous improvement in forage digestibility and lodging resistance can be achieved by pyramiding multiple effective QTL identified in the present study.