Impact of NDF degradability of corn silage on the milk yield potential of dairy cows.

The neutral detergent fibre (NDF) degradability of corn silage samples, measured in vitro (ivNDFd) by a filter bag system, was used to examine (i) the relationship between the ivNDFd and that calculated from acid detergent lignin (L) content (NDFd) and (ii) the impact of ivNDFd variations on the predicted milk yield (MY) of dairy cows fed corn silage based diets. A total of 173 samples of corn silage were collected during a period of three years (2001-03) in different dairy farms of the Po Valley (Northern Italy). Each sample was analysed for chemical composition and was also tested in triplicate for the ivNDFd using the DaisyII incubator (Ankom, Tech. Co., Fairport, NY, USA) with incubation time of 48hs. Moreover, the NDFd of samples was calculated from the L contents, while the measured ivNDFd values were used to estimate the NEl, the potential dry matter intakes (DMI) and to predict the MY of cows. Corn silage samples of the three years were similar for NDF and starch contents (44.2 and 30.7% DM, on average, respectively) while samples from 2003, in comparison with 2001 and 2002, had lower crude protein (6.9 vs 8.3-8.4% DM, P<0.01) and L contents (3.3 vs 3.6-3.9% DM, P<0.01) and higher ivNDFd values (53.3 vs 45.6-47.8%, P<0.01). The relationship between ivNDFd and NDFd was weak (R2=0.09, not significant). The MY predicted from the NEl content and DMI of corn silage (5.5 MJ/kg DM and 8.9 kg/d) minus the maintenance energy costs, was 11.5 kg/d on average (coefficient of variation 20%). Our simulations indicate that a variation of ivNDFd by +1.0% changes the NEl of corn silage to have an expected variation in milk yield of +0.15 kg/d. If the ivNDFd is also used to predict the corn silage DMI then a +1.0% variation in ivNDFd of corn silage produces an overall +0.23 kg/d MY variation. The present results indicate that ivNDFd is highly variable in corn silage populations and differences in this nutritional parameter have an appreciable impact on the predicted milk yield from dairy cows

Nitrogen and energy partitioning in two genetic groups of pigs fed low-protein diets at 130 kg body weight

The aim was to evaluate the effect of low-protein (LP) or low-amino acid diets on digestibility, energy and nitrogen (N) utilisation in 2 genetic groups (GG) of pigs (129±11 kg BW). Duroc×Large White (A) pigs were chosen to represent a traditional GG for ham production, and Danbred Duroc (D) pigs to represent a GG with fast growing rate and high carcass lean yield. Dietary treatments: a conventional diet (CONV) containing 13.2% CP, and two LP diets, one with LP (10.4%) and low essential AA (LP1), the second with LP (9.7%) and high essential AA (LP2). Compared to CONV, LP2 had the same essential AA content per unit feed, while LP1 the same essential AA content per unit CP. Feed was restricted (DMI=6.8% BW0.75). Four consecutive digestibility/balances periods were conducted with 24 barrows, 12 A and 12 D. Metabolic cages and respiration chambers were used. No significant difference between diets was registered for digestibility. Nitrogen excreted: 41.3, 33.4 and 29.0 g/d (P=0.009), for CONV, LP1 and LP2 diets, respectively. Nitrogen retention was similar between the diets. Heat production (HP) was the lowest for LP diets. There was a tendency (P=0.079) for a lower energy digestibility in D group. The D pigs also had a higher HP and hence a lower retained energy in comparison with the A pigs. In conclusion: it is possible to reduce N excretion using very LP diets and LP-low AA diets; Danbred GG have a higher heat production and a lower energy retention than A pigs

Effects of wilting and lactic acid bacteria inoculation on fermentation quality of white lupin and fababean silages

Fababeans and lupins are short-term catch crops with a high crude protein content, which provide a high forage yield in a short growing period. Legumes are difficult to conserve as silages because of their low water soluble carbohydrates content (WSC) and high buffer capacity. To our knowledge, little information is available on the ensiling of fababeans and lupins in Southern Europe. The research was carried out in Lodi (Italy) in order to evaluate the effects of wilting and inoculation with lactic acid bacteria (LAB) on fermentation characteristics of the resulting silages. The data show that both wilting and LAB inoculant significantly improved fermentation quality of the legumes silages

Methane yield from dry and lactating cows diets in the Po Plain (Italy) using an in vitro gas production technique

The aim of the study was to measure total gas and methane (CH4) production from 30 total mixed rations (TMRs) fed to dry and lactating cows in 20 commercial dairies in the Po Plain (Italy). Samples were analysed for chemical composition, in situ 48 h fibre digestibility (NDFD) and in vitro gas production (GP) and CH4 concentration at 24 h of incubation. NDFD of TMRs from dry and lactating cows was identical (52.1%; P=0.995). The TMRs fed to dry and lactating cows differed for GP (43.0 and 54.4 mL/200 mg DM, respectively; P<0.001) and CH4 (7.24 and 8.85 mL/200 mg DM, respectively; P=0.001), but not for CH4 as percentage of GP (24.3 and 23.7%, respectively; P=0.286). The data were analysed dividing the TMRs into quartiles depending on starch:ADF ratio; the average ratios of the groups 1, 2, 3 and 4 were 37, 77, 116 and 138, respectively. Increasing starch:ADF ratio determined a higher GP: 42.2, 51.4, 55.1 and 56.2 mL/200 mg DM for groups 1, 2, 3 and 4, respectively (P<0.001), whilst CH4 (mL/200 mg DM) was lower (P<0.001) for group 1 (7.12) in comparison with the others (8.82 on average). Acetate (% on total VFA) decreased for increasing starch:ADF ratio (P=0.009), whereas butyrate tended to increase (from 8.11 to 9.23% on total VFA; P=0.069) and the acetate:propionate ratio to decrease (from 3.35 to 3.09; P=0.082). The lack of a higher CH4 concentration in GP from diets richer in fibre might be attributed mainly to the relatively short time of incubation

Effects of benzoic acid on nitrogen, phosphorus and energy balance and on ammonia emission from slurries in the heavy pig

The effects of two dietary levels of benzoic acid on nitrogen, phosphorus and energy balance were evaluated in the typical Italian heavy pig during the last phase of growth. Six Landrace x Large White barrows of 125 kg body weight (BW) on average were used in a repeated 3x3 Latin Square design and housed in metabolic cages to collect faeces and urine separately, in 3 collection periods of 7 days, after 14 days of adaptation. The animals were individually housed in open circuit respiration chambers to determine the energy metabolism. The dietary treatments were as follows [% on dry matter (DM)]: i) diet C (control): 14.2 crude protein (CP), 3.7 EE, 13.8 NDF; ii) diet B05: diet C plus 0.5% benzoic acid; iii) diet B10: diet C plus 1.0% benzoic acid. DM fed was fixed at 6.8% BW0.75. Apparent digestibility was similar among treatments for all the parameters studied. Nitrogen (N) retention was 35.8, 37.4, 41.6% of intake N for C, B05 and B10, respectively, with no significant difference. Energy and phosphorus balances were not influenced by dietary treatments. Ammonia nitrogen emission from the slurry, expressed as a proportion of the initial slurry nitrogen, was decreased (P=0.049) by the inclusion of benzoic acid in the diet: 35.2, 28.1, 26.2% for C, B05, B10, respectively. The addition of benzoic acid to the diet determined a numerically decrease of the urinary pH. In conclusion, the inclusion of benzoic acid in the diet of the heavy pig is beneficial to the environment without effects on N, phosphorus (P) and energy balances

Effect of Alfalfa Silage Storage Structure and Roasting Corn on Production and Ruminal Metabolism of Lactating Dairy Cows

Abstract The objective of this study was to determine if feeding roasted corn would improve production and nutrient utilization when supplemented to lactating cows fed 1 of 3 different alfalfa silages (AS). Forty-two lactating Holstein cows (6 fitted with ruminal cannulas) averaging 77 d in milk and 43kg of milk/d pretrial were assigned to 2 cyclic changeover designs. Treatments were AS ensiled in bag, bunker, or O 2 -limiting tower silos and supplemented with ground shelled corn (GSC) or roasted GSC (RGSC). Silages were prepared from second-cutting alfalfa, field-wilted an average of 24h, and ensiled over 2 d. Production and N utilization were evaluated in 36 cows during four 28-d periods, and ruminal fermentation was evaluated with 6 cows during five 21-d periods. Experimental diets contained 40% AS, 15% corn silage, and 35% of either GSC or RGSC on a dry matter basis. No significant interactions between AS and corn sources were detected for any production trait. Although the chemical composition of the 3 AS was similar, feeding AS from the O 2 -limited tower silo elicited positive production responses. Yields of 3.5% fat-corrected milk and fat were increased 1.7kg/d and 150g/d, and milk fat content was increased 0.3% when cows were fed diets based on AS from the O 2 -limiting silo compared with the other 2 silages. The responses in milk fat were paralleled by an average increase in acid detergent fiber digestibility of 270g/d for cows fed AS from the O 2 -limiting tower silo. However, ruminal concentrations of lipogenic volatile fatty acids were unchanged with AS source. Cows fed RGSC consumed 0.6kg/d more dry matter and yielded 30g/d more protein and 50g/d more lactose than cows fed GSC diets. There was no evidence of increased total tract digestibility of organic matter or starch, or reduced ruminal NH 3 concentration, when feeding RGSC. Free amino acids increased, and isovalerate decreased in rumen fluid from cows fed RGSC diets. However, responses in production with roasted corn were mainly due to increased dry matter intake, which increased the supply of energy and nutrients available for synthesis of milk and milk components

In vitro effects of different levels of quebracho and chestnut tannins on rumen methane production, fermentation parameters, and microbiota

Both condensed and hydrolysable tannins (CTs and HTs, respectively) have the ability to reduce enteric CH4 production in ruminants. However, the precise mechanism of action is not fully understood. Among the proposed hypotheses are the reduction of ruminal digestibility, direct control action on protozoa, reduction of archaea, and a hydrogen sink mechanism. In this in vitro study, which simulated rumen fermentation, two additives, one containing CTs (70% based on DM) from quebracho and one with HTs (75% based on DM) from chestnut, at four levels of inclusion (2, 4, 6, 8% on an as-fed basis) were added to the fermentation substrate and tested against a negative control. Both types of tannins significantly reduced total gas (GP) and CH4 (ml/g DM) production during the 48 h of incubation. The lower GP and CH4 production levels were linked to the reduction in dry matter digestibility caused by CTs and HTs. Conversely, no significant differences were observed for the protozoan and archaeal populations, suggesting a low direct effect of tannins on these rumen microorganisms in vitro. However, both types of tannins had negative correlations for the families Bacteroidales_BS11 and F082 and positive correlations for the genera Prevotella and Succinivibrio. Regarding the fermentation parameters, no differences were observed for pH and total volatile fatty acid production, while both CTs and HTs linearly reduced the NH3 content. CTs from quebracho were more effective in reducing CH4 production than HTs from chestnut. However, for both types of tannins, the reduction in CH4 production was always associated with a lower digestibility without any changes in archaea or protozoa. Due to the high variability of tannins, further studies investigating the chemical structure of the compounds and their mechanisms of action are needed to understand the different results reported in the literature

Impact of red deer (Cervus elaphus) on forage crops in a protected area

During the last decades in Italy red deer (Cervus elaphus) density has locally reached very high values, with consequent serious problems due to the interaction with human activities, especially in protected areas. This study aims at quantifying the impact of red deer on herbaceous crops for forage production in a protected area in Northern Italy, that has been recently colonized by this species. To this aim, 14 exclusion enclosures on maize destined for whole plant silage production and 24 exclusion enclosures (not grazed, NG) on permanent meadows were established. For each of these sample plots (2 7 2 m), an adjacent control plot of identical surface area was established, freely available to red deer (grazed, G). Maize was harvested in September, whereas three grass cuts were harvested on meadows (May, July and August) and biomass production was weighed. Grass samples were collected, both in NG and in G plots, for chemical analysis. Red deer number was monthly estimated by night counts along fixed paths, using spotlights. The analysis of deer distribution allowed the distinction between two areas: High Density (HD: Northern area, with lower human disturbance, abundance of sheltered areas and an estimated deer density of 14\u201330 heads/km2) and Low Density (LD: Central and Southern areas, with an estimated deer density of 0\u20131.6 heads/km2). The percentage of maize plots with deer damage was significantly higher in HD than in LD area (83.3 vs 12.5%, respectively; P &lt; 0.05). In HD, red deer impact on maize crop was significant on plant height (NG = 250.75 \ub1 47.58 vs G = 136.87 \ub1 87.90 cm; P &lt; 0.05) and biomass production/plant (NG = 0.87 \ub1 0.42 vs G = 0.37 \ub1 0.39 kg/4 m2; P &lt; 0.05), whereas no significant effect was observed in LD. The percentage of plots of permanent meadows with deer damage did not differ between HD and LD areas. Significant losses were observed only in the second cut in the HD area for DM production, which was reduced by almost 14%. The chemical composition of the meadow forages showed only slight differences between G and NG plots (CP and NDF content significantly lower in G plots). The results obtained indicate that a high red deer density has an impact on the economic activity of farmers, particularly in term of maize losses (with estimated economic losses higher than \u20ac 20,000/farm/year), and suggest that appropriate management strategies, such as fencing of the crops at risk, are highly advisable