Prior Forage Type Influences Ruminal Responses to a Wheat Grain Challenge in Lactating Dairy Cows

To increase the dry matter and metabolisable energy intake of cows, dairy farmers often supplement pasture with concentrates and conserved fodder. Feeding large amounts of highly fermentable concentrates to cows can result in metabolic issues, such as ruminal acidosis, and thus safer but more efficient introduction strategies are desirable. We assessed the role that forages play in ruminal, behavioural and production responses to a wheat grain challenge in dairy cows with no previous wheat adaptation. Multiparous lactating Holstein dairy cows (n = 16) were fed a forage-only diet of either lucerne (Medicago sativa) hay, perennial ryegrass (Lolium perenne L.) hay or one of two cultivars of zero-grazing fresh perennial ryegrass herbage (Bealey or Base), for 3 weeks. The forage diet was then supplemented with crushed wheat grain at 8 kg dry matter/cow day−1, with no adaptation period. Wheat comprised between 32 and 43% of total dry matter intake. Cows fed hay maintained a higher mean ruminal fluid pH than those fed herbage, on both the forage-only diet (6.43 vs. 6.17) and the forage plus wheat diet (6.03 vs. 5.58). Following supplementation of wheat, cows fed herbage exhibited minimum ruminal fluid pH levels indicative of acute ruminal acidosis, at 5.15 and 5.06 for cultivars Bealey and Base, respectively. Furthermore, for both herbage cultivars, adding wheat resulted in a ruminal fluid pH under 6 for >20 h/day. The ruminal environment of cows fed lucerne hay remained most stable throughout the grain challenge, spending the least amount of time below pH 6.0 (9.0 h/day). Hay created a ruminal environment that was better able to cope with the accumulation of acid as wheat was digested. A combination of increased ruminating time and a slower rate of fermentation, due to higher neutral detergent fiber and lower metabolisable energy concentrations in the hays, is likely responsible for the higher ruminal fluid pH values. Forage plays a critical role in wheat introduction strategies; aggressive adaptation strategies could be implemented when a hay such as lucerne is used as the base forage.

The Apparent Metabolisable Energy Values of Palm Kernel Cake as Influenced by Enzymes and Cocktails

This study was conducted to quantify the effects of enzymes and their cocktails on the apparent metabolisable energy (AME) value of palm kernel cake to maximise enzymes’ advantages. There were eight treatments, each with three replicates in a completely randomised design with T1 as control. The experimental treatments had Xylanase, Multipurpose and phytase enzymes respectively for T2, T3 and T4, and a cocktail of xylanase and multipurpose, a cocktail of xylanase and phytase, cocktail of multipurpose and phytase, and cocktail of xylanase, multipurpose and phytase for T5, T6, T7 and T8. The feeding trial was done using the intubation method. Gross energy values were determined with calorimeter while calculated AME values were subjected to analysis of variance using Statistical Analysis System and treatment means separated by Duncan Multiple Range Test. Results show that individual enzymes, apart from phytase, significantly (p>0.05) improved the AME value of palm kernel cake. Treatment T8 was significantly (p>0.05) better than the other treatments. Each cocktail was significantly better than its respective individual enzymes except cocktail of multipurpose enzyme and phytase that was not significantly different from multipurpose enzyme but significantly (p>0.05) better than phytase. It was concluded that enzymes and cocktail of enzymes could be used to enhance the energy content of nonconventional feedstuffs thereby serving as a replacement to conventional energy feedstuffs.

The Potential of Deep Roots to Mitigate Impacts of Heatwaves and Declining Rainfall on Pastures in Southeast Australia

Declines in growing-season rainfall and increases in the frequency of heatwaves in southern Australia necessitate effective adaptation. The Sustainable Grazing Systems Pasture Model (SGS) was used to model the growth of three pasture species differing in root depth and root distribution under three different climate scenarios at two sites. The modelled metabolisable energy intake (in MJ) was used in a partial discounted net cash flow budget. Both the biophysical and economic modelling suggest that deep roots were advantageous in all climate scenarios at the long growing season site but provided no to little advantage at the short growing season site, likely due to the deep-rooted species drying out the soil profile earlier. In scenarios including climate change, the DM production of the deep-rooted species at the long growing season site averaged 386 kg/ha/year more than the more shallow-rooted species, while at the site with a shorter growing season it averaged 205 kg/ha/year less than the shallower-rooted species. The timing of the extra growth and pasture persistence strongly influenced the extent of the benefit. At the short growing season site other adaptation options such as summer dormancy will likely be necessary.

Effect of corn grain in a wet soya waste based total mixed ration silage on goat performance

The utilisation of wet soya waste as feed is low due to difficulties of storage and transportation,which needs to reach normal technical standard and comprehensive utilisation. The aim of thisstudy was to investigate the effect of cracked corn grain as a source of moisture absorbent andenergy in a wet soya waste based total mixed ration silage on goat performance. Ten growing goatswere assigned to two feeding treatment groups for 84 days. Goats in Group 1 received Napier grass(Pennisetum purpuerum) ensiled with 30% soya waste (w/w) and 8% molasses (w/w) (T1) ascontrol, and Group 2 received same grass ensiled with 30% soya waste (w/w) and 15% crackedcorn grain (w/w) (T2). All goats received their respective silage ad libitum after 2 months offermentation. The pH in T1 silage was 4.1, while pH in T2 silage was 4.0. Goats fed T2 diet showedhigher intakes of dry matter, organic matter and metabolisable energy than those of goats fed T1diet, while it was observed vice versa for neutral detergent fibre intake. However, there was nodifference in average daily gain and feed conversion ratio between two treatment diets. Results ofthis study indicate that cracked corn grain, as a source of moisture absorbent and energy, can beused successfully in wet soya waste based total mixed ration silage for growing goats.

Effects of dietary energy level and guanidino acetic acid supplementation on growth performance, carcass quality and intestinal architecture of broilers

Energy, known as the most expensive nutrient in broiler feed, is what strongly adjusts and affects the growth of broilers. Creatine has a key role in cellular energy metabolism and could be synthesised from guanidinoacetic acid (GAA) in the liver; however, its de novo synthesis is not able to adequately fulfil the demand of energy metabolism, especially in fast-growing modern broilers. So the aim of the study was to evaluate the efficiency of commercial GAA in energy-reduced broiler diets on performance and intestinal development. Overall, 11 400 day-old Ross 308 chicks were randomly allocated to six dietary treatments with ten replicates in each. Dietary treatments were designed as a 3 × 2 factorial arrangement with three levels of dietary metabolisable energy (AME_n) recommended by Aviagen for Ross 308 broilers (12.55 MJ/kg, 12.97 MJ/kg and 13.38 MJ/kg for starter, grower and finisher, respectively), 0.209 MJ/kg and 0.418 MJ/kg reduced and two levels of GAA (0.00% and 0.06%). There was no significant GAA × AME_n interaction for all performance parameters, carcass traits and jejunal morphological parameters (except for the villus width). Reduction of dietary AME_n (0.209 MJ/kg and/or 0.418 MJ/kg) caused a significant depression in body weight (BW) gain (P < 0.001) and feed conversion ratio (FCR) (P < 0.001). However, a decreasing AME_n level increased villus height (P < 0.003) and villus surface area (P < 0.03), while crypt depth and villus width were similar. The GAA improved final BW and FCR by 1.77% and 1.66%, respectively (P < 0.001). Birds fed low energy diets supplemented with GAA showed a significant improvement in the performance so that BW and FCR were the same as in the control birds; however, no such positive effects were obtained in jejunal villus development. Hence, it might be concluded that 0.06% GAA supplementation improves BW and FCR and can save at least 0.209 MJ/kg dietary AME_n in broiler diets.