Effects of Hybrid and Maturity Stage on in Vitro Rumen Digestibility of Immature Corn Grain

This study aimed to evaluate the influences of hybrids (HYB) and maturity stage (SAMP) on in vitro rumen digestibility of immature corn grain. Four HYB (Gigantic, Y43, Klips and 9575) from the FAO group 700 were grown under identical agronomic conditions. First sampling (T1) was done after 95 days from seedling and then 4, 8, 13, 18 and 27 days later (T2 to T6). In vitro starch digestibility (STD_7h) and gas production (72 h) were measured. Whole plant and grain dry matter (WP_DM and GR_DM, respectively) and zein content were significantly affected (P<0.01) by HYB and SAMP. Starch content was significantly affected by HYB, SAMP and their interaction. It increased from T1 to T4 (from 67.47 to 72.82% of GR_DM) and then tended to plateau. Concurrently, STD_7h significantly decreased with advancing SAMP and was also affected by HYB. With advancing maturity, total volatile fatty acids (VFA) significantly decreased, with an increase of acetate and a decrease of propionate molar proportion (P<0.01). Gas production rate (GP_c) was significantly affected by HYB, SAMP and HYB×SAMP. Whole plant grain DM correlated (P<0.01) positively with grain starch content (r=0.60 and 0.64) but negatively with STD_7h (r=-0.39 and r=-0.63) and VFA concentration (r=-0.59 and -0.75). Zein percentage in crude protein negatively affected (P<0.01) total DM (r=-0.65,), STD_7h (r=-0.73) and GP_c (r=- 0.68). Results suggest that genotypes and maturity stages influence DM and rumen starch digestibility of immature corn grain and in this respect zein can play a significant role

In vitro digestibility of field pea as influenced by processing methods

Field pea meals exposed to different treatments (flaking, extrusion, expansion, dry heating at 150&deg;C/15&rsquo; or 30&rsquo;, dry heating at 150&deg;C/30&rsquo; after addition of 1% of xylose, 4% NaOH addition, microwave irradiation at 800 W for 6&rsquo; or 9&rsquo;) were controlled for their 6 and 24 hours in vitro fermentability by the gas production (GP) technique. Flaking and extrusion accelerated initial fermentation but tended to reduce 24h GP, whereas dry heating and microwaves mainly improved final gas volume, but NaOH had the opposite effect. Apparent dry matter digestion at 6h was lowered by dry heating, NaOH addition and the shorter microwave irradiation. Xylose addition did not substantially change the effects of dry heating, but lowered the initial disappearance. Ammonia concentration was in general lowered by the treatments, suggesting a reduction in protein degradability but also a possible higher microbial uptake for protein synthesis. Microwave irradiation had limited effects on all the parameters. Dry heating, with or without xylose addition, seems interesting to increase rumen escaping protein fraction without accelerating starch fermentation that could expose to higher risks of rumen acidosis

Effect of some phytoextracts on in vitro rumen digestion

Plant secondary compounds, generally considered in the past as antinutritional factors, can be worth to be tested in animal production systems as alternative to traditional chemical allopathic drugs and to enhance animal health and performance but, in ruminants, attention should be paid for possible interference with rumen metabolism. Particular interest assume phytoextracts with claimed antioxidant, antinflammatory or immunomodulant potential. Five plant extracts from Curcuma longa, Andrographis paniculata, Ginko biloba, Salix chilensis and Echinacea angustifolia were tested in vitro for their possible effect on rumen fermentations and feeds digestion. The trials were carried out by the Ankom DaisyII incubator, testing three concentrations of each extract (20, 60 and 120 mg/L). Corn meal, grass hay, alfalfa hay and beet pulp were incubated in F57 bags. Dry matter digestibility, pH, ammonia and VFA concentration were measured after 48 h of incubation. S. chilensis slightly reduced pH (P<0.05). G. biloba and S. chilensis did not affect feeds dry matter digestibility, that was increased by the addition of A. paniculata in fibrous feeds in a dose dependent manner, but not in corn meal. On the contrary, C. longa extract slightly but significantly reduced digestibility of all feeds samples and also ammonia concentration. All plant extracts did not significantly alter VFA concentration, suggesting a possible effect on microbial efficiency: ameliorated by A. paniculata and lowered by C. longa. All the tested plant extracts did not induced major changes in rumen metabolism, at least when evaluated in vitro, and can be candidates for in vivo utilisation. Nevertheless, their in vivo effects should be tested, mainly for long lasting utilisation and with attention to their possible consequences on whole digestive tract

Effects of defoliation on whole-plant maize characteristics as forage and energy crop

Hail affects yield and quality of maize crops, and consequences also depend on the growth stage at which the injury occurred. Whole-plant maize (WPM) silage is often used within the same farm for cattle feeding and biogas production. The present study aimed to verify the effects of hail damage, simulated by artificial defoliation, on yield and chemical and nutritional features, as well as on biochemical methane potential (BMP) of maize forage. In a randomized block design with three replicates, four defoliation levels (0%, 33%, 66% and 100% of leaf area removal respectively) have been applied at either the V12 (12th leaf), R1 (silking) or R3 (milk) stages for two consecutive years. WPM yield, chemical and nutritional features, and BMP were measured. Dry-matter (DM) yield per hectare was progressively reduced (p < 0.001) with increasing levels of defoliation and with application at V12 in comparison with R1 or R3 (1.26 vs. 1.39 and 1.46 kg ha −1 for V12 vs. R1 and R3; p < 0.003). Nutritive value and BMP per unit of product were less altered than dry-matter yield per hectare by defoliation. Anticipating defoliation reduced net energy for lactation (5.26 vs. 5.46 MJ kg −1 DM for V12 and R3 respectively; p = 0.02). Total defoliation resulted in an accumulation of nitrates (NO 3 ) compared to the other treatments (3.98 vs. 1.53 g NO 3  kg −1 DM; p < 0.001). BMP was mainly reduced by early and complete defoliation. Equations were developed to estimate the effects of defoliation on yield, composition, and nutritive and energetic values of WPM

Estimation of dry matter intake by n-alkanes in dairy cows fed TMR: effect of dosing technique and faecal collection time

Estimation of individual intakes in dairy cows would be beneficial to select animals according to efficiency of milk production. The n-alkanes technique has been used to estimate intake by dairy cows in free stall barns, limiting faecal samples to one or two per day, but diurnal variation in the ratio of dosed to natural alkanes in faeces represents a source of error. We aimed to adapt this technique to estimate feed intake on a large number of lactating dairy cows housed on commercial dairy farms. Using a change-over design, six lactating cows fed a TMR diet were given a dose of 0.5 g/day of C32 n-alkane administered once a day as a drench (DRE) or top fed (TP). Feed offered and refused were weighed daily. After the lead-in phases, faeces were collected at 0700 hours, 1400 hours and 1900 hours on the last 5 days of each dosing period. Dry matter intake (DMI) was estimated from C31, C33 and C32 concentrations in feeds and in faeces for each dosing system and sampling time. DMI estimated from C31:C32 ratio was better correlated with measured individual DMI than estimates from C33:C32 ratio. For DRE, the best correlation was for sampling at 1400 hours (R2 64 0.96, P < 0.001), but estimated DMI for the 1400 hours sampling was much higher than the actual DMI. For TP, the best correlation was for sampling at 0700 hours (R2 64 0.83, P < 0.001). Feeding C32 n-alkane and collecting faeces once a day at the same time (0700 hours) represents a valuable protocol to measure individual intake on a large number of animals. \ua9 CSIRO 2014