G.M. Crovetto

Energy and nitrogen balance in heavy pigs fed different fibre sources

The aim of the experiment was to investigate the possible differences in the utilization of different fibrous feeds by the heavy fattening pig. Eight Landrace×Large White barrows of 85 kg BW were paired and fed, in a Latin Square design, four diets containing different dietary fibre sources: 8% coarse soft wheat bran (control, C), 24% milled wheat bran (MB), 24% coarse wheat bran (CB), and 16% dried beet pulp (BP). Compared to C, the MB and CB diets significantly decreased the digestibility of most parameters, while the BP diet lowered the digestibility of N and EE, increased fibre digestibility, and had similar DM, OM and energy digestibility. Compared to BP, diets MB and CB had significantly higher N and EE digestibility, but lower DM, OM, fibre and energy digestibility. CH4 emission was significantly increased by BP compared with C, MB and CB. Compared to C, metabolisable energy was significantly lowered by MB and CB, but not by the BP diet. The BP diet caused significantly (P<0.01) greater heat production (47.3% of intake energy) than the MB (45.2%) and CB (45.0%) diets; heat production for diet C was intermediate (46.4%). The retained energy and N retention were similar for all treatments. MB and BP diets had significantly lower NE than the other two diets. The results suggest that, because the heavy pig can use dietary fibre better than younger pigs, wheat bran and beet pulp have a higher energy content than reported from trials on animals of lower bodyweight.

Effect of the stage of maturity on the nutritive value of whole crop wheat silage

Abstract An in vivo digestibility and calorimetric experiment was performed on eight adult wethers to determine the digestibility and net energy content of wheat silages obtained from whole plants cut at different stages of maturity. Wheat ( Triticum aestivum L., var. Eridano) was harvested at the boot (B), midbloom (MB), milk (M) and dough (D) stages of maturity. The wethers were fed ad libitum in a 4×4 latin square digestibility trial. Each collection period lasted eight days with 3×24 h-cycles of respiration trials (indirect calorimetry in respiration chambers). In vitro organic matter digestibility (IVOMD) was determined on dried samples of whole wheat cut from the same field at 10 different stages between boot and dough. Silage quality parameters were optimum for all stages. DM, OM and energy intake were significantly higher in the first and last stages of maturity (B and D) than in the medium stages (MB and M). DM, OM and energy digestibility decreased significantly from B to M stage but did not change between the last two stages. In contrast, CF, NDF and ADF digestibility decreased significantly with maturity. IVOMD had a quadratic trend of variation as a function of the stage of maturity, similar to the in vivo data, with the lower value at the M stage. Metabolizability ( q =ME/GE) followed the same trend of energy digestibility. NE l decreased with increasing stage of plant growth but the difference was significant only between the first stage and the last three stages. The nutritive values of the whole-crop wheat silages was very high for the B stage and decreased with successive stages of maturity (7.74, 6.41, 5.69 and 5.39 MJ NE l /kg DM at the B, MB, M and D stages). In contrast, DM yield was minimum at the B stage (3.3 t/ha) and increased with increasing maturity up to 9.6 t/ha at the D stage. As a consequence, a satisfactory compromise between yield and nutritive value would involve harvesting whole-crop wheat just before the milk stage.

Effect of dietary starch concentration and fish oil supplementation on milk yield and composition, diet digestibility, and methane emissions in lactating dairy cows

The aim of this study was to evaluate the effects of diets with different starch concentrations and fish oil (FO) supplementation on lactation performance, in vivo total-tract nutrient digestibility, N balance, and methane (CH4) emissions in lactating dairy cows. The experiment was conducted as a 4×4 Latin square design with a 2×2 factorial arrangement: 2 concentrations of dietary starch [low vs. high: 23.7 and 27.7% on a dry matter (DM) basis; neutral detergent fiber/starch ratios: 1.47 and 1.12], the presence or absence of FO supplement (0.80% on a DM basis), and their interaction were evaluated. Four Italian Friesian cows were fed 1 of the following 4 diets in 4 consecutive 26-d periods: (1) low starch (LS), (2) low starch plus FO (LSO), (3) high starch (HS), and (4) high starch plus FO (HSO). The diets contained the same amount of forages (corn silage, alfalfa and meadow hays). The starch concentration was balanced using different proportions of corn meal and soybean hulls. The cows were housed in metabolic stalls inside open-circuit respiration chambers to allow measurement of CH4 emission and the collection of separate urine and feces. No differences among treatments were observed for DM intake. We observed a trend for FO to increase milk yield: 29.2 and 27.5kg/d, on average, for diets with and without FO, respectively. Milk fat was affected by the interaction between dietary starch and FO: milk fat decreased only in the HSO diet. Energy-corrected milk (ECM) was affected by the interaction between starch and FO, with a positive effect of FO on the LS diet. Fish oil supplementation decreased the n-6:n-3 ratio of milk polyunsaturated fatty acids. High-starch diets negatively influenced all digestibility parameters measured except starch, whereas FO improved neutral detergent fiber digestibility (41.9 vs. 46.1% for diets without and with FO, respectively, and ether extract digestibility (53.7 vs. 67.1% for diets without and with FO, respectively). We observed a trend for lower CH4 emission (g/d) and intensity (g/kg of milk) with the high-starch diets compared with the low-starch diets: 396 versus 415g/d on average, respectively, and 14.1 versus 14.9g/kg of milk, respectively. Methane intensity per kilogram of ECM was affected by the interaction between starch and FO, with a positive effect of FO for the LS diet: 14.5 versus 13.3g of CH4/kg of ECM for LS and LSO diets, respectively.

Milk production, nitrogen balance, and fiber digestibility prediction of corn, whole plant grain sorghum, and forage sorghum silages in the dairy cow

Total mixed rations containing corn (CS), whole plant grain sorghum (WPGS), or forage sorghum (FS) silages were fed to 6 primiparous Italian Friesian cows to determine the effects on lactation performance, nutrient digestibility, and N balance. Furthermore, the relationship between in vivo total-tract neutral detergent fiber (NDF) digestibility (ttNDFD) and the ttNDFD derived by the Cornell Net Carbohydrate and Protein System (CNCPS) model was assessed. Cows were assigned to 1 of 3 diets in a replicated 3 × 3 Latin square with 28-d periods. The experimental treatment was silage type and 3 different silages were included in the diets. The diets were formulated to be iso-NDF. Accordingly, each diet was formulated to contain 41.5% CS silage, 36.7% WPGS silage, or 28.0% FS silage, on a DM basis. Starch content was balanced by adding the appropriate amount of corn meal. Separate collection of total urine and feces was performed. Dietary forages were analyzed for in vitro NDF digestibility (6 and 24h of incubation) to predict fiber digestion rate with 2 NDF pools (digestible and indigestible). Rumen digestibility of the potentially digestible NDF pool was predicted using CNCPS version 6.1, using the in vitro forage fiber digestion rate. The ttNDFD was predicted assuming that intestinal digestibility of the NDF amount escaping rumen digestion was 20%, according to the CNCPS model. Dry matter intake was decreased by approximately 1.8 kg/d in cows fed the FS diet compared with the other diets, probably for the greater particle size of FS diet. Hence, milk yield (kg/d) was lowest for FS (23.6), intermediate for WPGS (24.6), and highest for the CS diet (25.4). Milk urea N (mg/dL) was highest for FS (12.9), intermediate for WPGS (11.9), and lowest for CS (10.7) diet. In vivo ttNDFD (%) was 51.4 (CS), 48.6 (WPGS), and 54.1 (FS); this was probably due to a higher retention time of FS diet in the rumen rather than to a better quality of the FS silage, as confirmed by in situ and in vitro results. Urinary N excretion (% N intake) was highest for FS (31.8), intermediate for WPGS (29.3), and lowest for the CS (27.5) diet. The predicted ttNDFD (37.7, 36.3, and 39.5% for CS, WPGS, and FS, respectively) were lower than the in vivo results. Providing an adequate starch supplementation, whole plant grain sorghum silage can replace corn silage in dairy cows TMR. Forage sorghum silage had rumen NDF digestibility comparable to the other silages; however, it had a negative effect on dry matter intake and milk production, probably due to an inadequate effect of processing.

Nutritive value of different hybrids of sorghum forage determined in vitro

Abstract Eight hybrids of sorghum forage were tested in large plots of two farms in two consecutive years to evaluate their chemical characteristics, nutritive value and yield as a possible substitute for maize silage. Two or three cuts were made depending on climatic conditions. On forage samples taken at ensiling chemical analyses and 24 h gas production were performed, to predict the NEl content. In comparison with maize silage, the sorghum hybrids registered higher protein (13.7% on DM) and NDF (62.6% on DM) contents. Interestingly, the fibre fraction had a low lignin content (3.1% on DM). NEl content ranged from 4.53 to 5.28 MJ/kg DM, the latter for the hybrid with the lowest NDF content. Hybrid effect was significant for ash, NDF, ADF and NEl contents, whilst cut effect was significant for EE, CP, NDF and ADF. Yield was strongly influenced by fertilisation; when the latter was applied, it was in the range of 10-18 t DM, 1.7-2.8 t CP and 47-88 thousand MJ NEl per hectare, as a sum of the 23 cuts. Sorghum forage seems to be a possible alternative to the fibrous maize silage fraction in diets of lactating cows, and an excellent forage for the rations of dry cows and heifers.

Digestibility and metabolic utilization of diets containing whole-ear corn silage and their effects on growth and slaughter traits of heavy pigs

The aim was to evaluate 2 levels of dietary inclusion of chopped whole-ear corn silage (WECS) on energy and nutrient utilization, growth, and slaughter performances of heavy pigs. Two in vivo experiments were conducted to determine digestibility and metabolic utilization of WECS using 18 barrows weighing 118 ± 8 kg BW on average, metabolic cages and respiration chambers (Exp. 1), and the effect of WECS on the growth performance and carcass traits on 42 barrows from 90 to 170 kg BW (Exp. 2). In both experiments, pigs were fed 3 experimental diets: a control diet (CON) containing cereal meals, extracted soybean meal, and wheat bran (80%, 9%, and 8% of DM, respectively) and 2 diets containing 15% (15WECS) or 30% WECS (30WECS) on a DM basis in place of wheat bran and corn meal. The diets were prepared daily by mixing the WECS to a suitable compound feed. Feed intake was always restricted to allow a daily DMI of 7.2% BW(0.75) in Exp. 1 and from 8.0% to 6.5% BW(0.75) in Exp. 2. Diets had similar NDF contents (15.2% to 15.8% of DM), and WECS inclusion resulted in a slight reduction in CP content (from 14.0% to 13.6% of DM) and a considerable decrease in P content (from 0.47% to 0.30% of DM). Digestibility of OM, CP, and fat was similar among diets, whereas P digestibility was lower (P < 0.05) for the 30WECS diet (33.5%) in comparison with the CON and 15WECS diets (45.5% and 44.1%, respectively). Nitrogen lost in feces and urine and N retained were not different among diets, whereas P retained decreased with the increase of WECS (5.4, 3.7, and 2.2 g/d for the CON, 15WECS, and 30WECS diets, respectively; P < 0.05). No difference among diets was observed for energy balance. The WECS contained 13.48 MJ ME and 9.39 MJ NE/kg DM. In Exp. 2, feed intake was not depressed by WECS inclusion, and the ADG for the whole experiment was not different among dietary treatments (from 737 to 774 g/d). Fecal pH was lower (P < 0.05) for the WECS diets than the control diet (7.10 and 7.00 vs. 7.40) and for the sampling at 150 kg BW than that at 130 and 110 kg BW (6.96 vs. 7.29 and 7.24). At slaughter, lean percentage in the carcass was lower in the 30WECS diet than those of the other 2 diets (46.8% vs. 48.3% and 48.6%, P = 0.05). The overall experimental data obtained in both trials indicate that substitution of wheat bran and corn meal for WECS (up to 30% of DM) does not affect, with the exception of P utilization and carcass leanness, energy and nutrient utilization and performance of heavy pigs in the last phase of growing.

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.

Effect of beet pulp on growing performance, digestibility, N balance, and ammonia emission in the heavy pig

Riassunto Effetto delle polpe di bietola disidratate su prestazioni zootecniche, digeribilità, bilancio dell’azoto ed emissioni ammoniacali nel suino pesante. Scopo del lavoro è stato quello di valutare in che misura l’inclusione nella dieta di un alimento ricco in carboidrati non amidacei ben digeribili, quale le polpe di bietola disidratate, influenzi le emissioni ammoniacali dalle deiezioni e le prestazioni zootecniche del suino pesante tipico italiano nella fase finale del ciclo di ingrasso. In 12 box sono stati stabulati 72 suini, da 106 a 170 kg di peso, per testare tre diverse diete contenenti 0 (C), 15 (BP1) e 30% (BP2) di polpe di bietola disidratate. Con le diete contenenti polpe di bietola è stata registrata una maggior escrezione fecale di N, ma una minor escrezione urinaria e una ridotta emissione di NH3 dalle deiezioni. Le prestazioni zootecniche sono risultate simili per le diete C e BP1 e leggermente peggiori per BP2.

Feeding behaviour, digestibility, energy balance and productive performance of lactating goats fed forage-based and forage-free diets

Abstract Six lactating Saanen goats have been used in a Latin Square design to evaluate a grass-based diet (G), a hay-based diet (H) and a nonforage diet (NF). On dry matter, grass and hay contributed for 55% of the diets and had 13.7 and 16.1% CP, 55.4 and 49.4% NDF, 38.0 and 31.6% ADF, respectively. Diet NF had beet pulp, cracked carob beans and whole cottonseed as main ingredients, with more than 75% of the particles greater than 2 mm. Independently of the dietary treatment, the goats spent more time eating than ruminating. Diet NF proved to be effective in stimulating chewing activity, despite a trend for a lower chewing activity for eating (178, 185, 125 min/kg DMI for diets G, H and NF, respectively), but not for ruminating (84, 80, 80 min/kg DMI for diets G, H and NF, respectively). Feed intake did not differ among diets, while regarding digestibility diet NF had the highest values for DM (74.1%), OM (75.7%) and non-fibrous carbohydrates (92.0%), but the lowest for ADF (44.5%). For treatments G, H and NF milk yields were 3011, 3688 and 3212 g/d (P<0.05 between H and G), while milk fat and protein were respectively 3.37, 3.24, 2.96% (P<0.05 between G and NF) and 3.11, 3.32, 3.29%. Milk urea N was lower for diet NF (18.8, 18.6, 12.7 mg/100 ml, P<0.001). Diet NF increased the concentration of the short chain fatty acids of milk fat and decreased the content of C18:0, C18:1 and C18:3 in comparison to the other two diets. No difference among treatments was recorded for CLA. Intake energy was digested to a lesser extent for diet G (68.9, 70.0, 72.7%, P<0.05 between G and NF) due to its poor quality forage. Urinary energy losses reflected the corresponding protein contents of the diets, while no difference was recorded for methane production. ME resulted higher for diet NF (60.0, 60.7, 65.1% of the intake energy, P<0.01), while heat production and milk energy yield were similar in the three treatments. Diet NF had a higher ME content (11.13, 11.26, 11.93 MJ/kg DM, P<0.05), while no significant difference among the diets was recorded in terms of kl (0.64, 0.70, 0.69) and NEl (7.20, 7.93, 8.30 MJ/kg DM). It is concluded from the study that a nonforage diet with an adequate amount of structured fibre could substitute a ration based on poor quality forage in lactating goats; however, good forage seems to enhance milk performance to a greater extent.

Effects of a selection of additives on in vitro ruminal methanogenesis and in situ and in vivo NDF digestibility

The effects of 18 essential oils, yeast, Quebracho tannin and Quillaja saponin on ruminal methane and gas production (GP) were studied in vitro. A lactating cow diet was incubated with rumen inoculum. Doses of the additives (mg/L) were: essential oils = 500; tannin = 67; yeast = 8.35 and 16.7; and saponin = 300. Lemongrass, estragole, eugenol, geraniol, limonen, thyme oil and thymol produced less gas (overall mean 33.8 mL/200 mg dry matter (DM)) than control (43.6 mL/200 mg DM; P < 0.001). Methane produced (mL/200 mg DM) by guaiacol (10.7), lemongrass (9.6), limonene (11.4), thyme oil (10.9) and thymol (2.1) was lower than control (12.5) (P < 0.001). Methane percentage on total GP was lower (P < 0.001) for cinnamic alcohol (25.4), guaiacol (24.5), thymol (19.7) and vanillin (26.3) than control (28.8). In a second experiment, thymol, guaiacol and yeast were added to the diet of dry fistulated cows to determine in situ neutral detergent fiber digestibility (NDFD) of six forages and in vivo dietary NDFD. Thymol and yeast decreased in situ NDFD after 24 h (33.9% and 33.5% vs. 38.1%; P = 0.008). Thymol decreased in vivo total tract NDFD (40.8% vs. 51.4%; P = 0.02). Differences in GP and methane levels were registered within classes of additives. A careful selection of additives may allow for the manipulation of ruminal fermentation.