No abstract

Wet distillers grains with soluble (WDGS) were blended with whole maize plants on an as-fed basis at 0%, 20%, 30%, and 40% and ensiled in 3 L bottles to evaluate the silage fermentation characteristics and ensiling quality in a complete randomized design. Each treatment was ensiled in 15 mini-silos and three bottles were opened on days 7, 21, 42 and 120. Each treatment was sampled for chemical composition and silage fermentation parameters. There was a steady decrease in dry matter (DM) concentration of silage with increasing WDGS inclusion level over time. Initial pH (at day 0) decreased with increasing level of WDGS inclusion, with 40% WDGS inclusion recording the lowest pH (3.6) at day 120. Lactic acid concentration was slightly lower for WDGS-blended silages compared with the control. In contrast, the acetic acid concentration for WDGS-blended silage increased across all treatments, suggesting a possible diminished effect of clostridium bacteria in the silage owing to a reduced pH. The acid detergent fibre (ADF), neutral detergent fibre (NDF) and IVDOM (in vitro digestible organic matter) did not differ at the time of ensiling among treatments. During post ensiling, ADF increased slightly over time for WDGS-blended treatments (at 120 days). The results from this study indicated that WDGS could be ensiled effectively with maize plants without compromising silage quality. ______________________________________________________________________________________

The development of greenhouse gas mitigation strategies has become an important issue globally. Enteric methane (CH4) emissions from livestock do not only contribute substantially to the environmental footprint of livestock production but it also represents a loss of energy that could be channelled towards animal growth and production. In this study 14 sub-tropical grass species typical of transitional rangeland regions of South Africa were characterised in terms of ecological status, chemical composition, in vitro total gas and CH4 production. The aim of the study was 2-fold: to identify grass species that could be selected for low enteric CH4 production; evaluate the influence of rangeland ecological status on the methanogenic potential of a rangeland. Grass samples were collected by hand, air-dried, milled and analysed for nutrient composition, in vitro organic matter digestibility (IVOMD) and in vitro gas and CH4 production. Cenchrus ciliaris and Urelytrum agropyriodes produced the highest 48-h in vitro CH4 of 17.49 and 14.05 mL/g DM digested respectively. The lowest 48-h in vitro CH4 was produced by Andropogan gayanus and Bothriochloa bladhii with 5.98 and 6.08 mL/g DM digested respectively. The evaluated grass species were overall of poor quality with low CP concentrations ranging from 2.4% for Trachypogon spicatus to 6.7% for Digitaria eriantha and IVOMD ranging from 22.5% for Andropogon gayanus to 42.2% for Urelytrum agropyriodes. Decreaser grass species presented with higher in vitro CH4 production compared with Increaser I and Increaser II grass species in the present study. The results of the study emphasise the importance of including the nutritional potential of grass species for improved livestock production when evaluating grass species for possible greenhouse gas mitigation strategies.

Context Reducing emissions of greenhouse gases from livestock production systems is a global research priority. Forages that contain condensed tannins, such as the perennial legume Lespedeza cuneata, may help to reduce ruminant methane (CH4) emissions. Aims The objective of this study was to investigate the effect of feeding different levels of L. cuneata hay on feed intake and enteric CH4 emissions of sheep fed a basal diet of subtropical Eragrostis curvula hay. Methods Four adult ruminally cannulated Dohne Merino wethers with initial bodyweight of 65.5 ± 3.5 kg were used in the experiment in a 4 × 4 Latin square design. The four experimental treatments were E. curvula hay substituted with 0%, 30%, 60% and 90% L. cuneata hay. Each of four experimental periods lasted 27 days, which consisted of a 14-day adaptation period, a 7-day digestibility trial, and a 6-day CH4-measurement period. During the 6-day CH4-measurement period, CH4 emissions were measured continuously over a 24-h period by using an open circuit respiration system. Key results Dry matter intake (DMI, g/kg W0.75) was higher (P < 0.05) for sheep receiving 60% and 90% L. cuneata than 0% and 30% L. cuneata (77.33 and 84.67 g/kg W0.75 vs 62.96 and 62.71 g/kg W0.75). The increase in DMI corresponded with a linear increase in DM digestibility of the experimental treatments from 38% to 45% as the level of L. cuneata substitution increased. Methane yield was not influenced (P > 0.05) by 30% inclusion of L. cuneata (17.6 g CH4/kg DMI) but decreased (P < 0.05) as the inclusion level increased to 60% and 90% (13.8 and 14.3 g CH4/kg DMI). Conclusions Inclusion of L. cuneata hay in a diet based on E. curvula hay improved diet digestibility, and led to increased concentrations of crude protein, neutral detergent fibre and non-fibre carbohydrates. Substituting E. curvula hay with 60% L. cuneata on a DM basis resulted in the greatest reduction in CH4 yield of 21.4% compared with a diet of 100% E. curvula. Implications The results suggest that L. cuneata has the potential to reduce CH4 yield and possibly increase production from sheep by improving diet DM digestibility and through improved DMI.

The high moisture content of wet distillers' grains with solubles (WDGS) has limited its feeding value despite the relatively high nutritive value. The co-ensiling with whole-plant maize, as a complementary feed, was evaluated for growing lambs by formulating diets whose contents were: whole plant maize silage (WPMS) + sunflower oilcake meal (SOM) (control, WPMS + SOM), whole plant maize silage + dried distillers' grains (WPMS + DDGS), and whole-plant maize (WPM) co-ensiled with WDGS (WPM -WDGS). Rumen fermentation parameters and in situ degradability of the diets were evaluated using three cannulated Merino wethers in a cross over 3 × 3 Latin square design experiment that lasted 39 days. Concurrently, feed intake and growth performance of South Africa Mutton Merino lambs (29.7 ± 3.6 kg) were evaluated over 45 days.The WPMS + DDGS diet had a lower rate of dry matter degradation (p < 0.05) compared to the WPMS + SOM and WPM-WDGS diets. However, the rapidly fermentable fraction, as well as the progressively fermentable fraction of the diet dry matter, was not different (p > 0.05). No differences in rumen volatile fatty acid, ammonia nitrogen concentration nor rumen pH of the wethers as a result of diet differences were observed. Lambs consuming the WDGS-based diet had a lower average daily intake and average daily gain (p < 0.05) compared to lambs consuming the DDGS and WPMS-based diets. However, the feed conversion ratio was not affected by diet differences (p > 0.05). In conclusion, co-ensiling WDGS with whole-plant maize provides the opportunity for the long-term storage and utilization of WDGS in lamb feeding.