Stefano Schiavon

Nitrogen excretion in dairy cow, beef and veal cattle, pig, and rabbit farms in Northern Italy

Abstract Reference values for N excretion of different livestock production systems are required for the application of the Nitrate Directive (91/676/EC). A survey aimed to estimate N excretion from on-farm measurements of feed consumption and performance of dairy cows (104 herds, 9,984 cows), growing cattle (40 farms, 40,157 young bulls), veal calves (34 farms, 49,206 calves), growing pigs (39 farms, 161,278 pigs) and rabbits (54 farms, 65,664 reproducing does) was conducted in Veneto from 2002 to 2003. N excretion was computed as the difference between N consumption and N retained in animal products. Dairy cow yielded 8,366 ± 1,646 kg/year of milk, consumed 6,600 ± 928 kg/year of DM, containing 2.45 ± 0.2 % DM of N, and excreted 116 ± 25 kg of N/year. No significant correlation was found between milk yield and N excretion, but the correlation between dietary N concentration and N excretion was significant (r=0.66). For growing cattle, the following mean values were achieved: daily gain 1.25 ± 0.19 kg/d; feed conversion ratio 6.9 ± 0.9 kg of DM/kg, rounds/year 1.66 ± 0.38. Nitrogen consumed, retained and excreted were, respectively, 68.7 ± 5.4, 11.4 ± 1.9 and 57.3 ± 4.9 kg/place/year. For veal calves, N consumed was 24.1 ± 1.9 kg/place/year, 12.1 ± 0.8 kg of which were retained in the body and 12.0 ± 1.5 kg were excreted. For heavy pig production, N consumed, per place and per year, averaged 19.0 ± 1.9 kg, N retained was 5.2 ± 0.5 kg and N excreted was 13.8 ± 0.4 kg. In the close-cycle rabbit farms, the doe and the relative growing rabbits (43 sold per year) consumed 11.2 ± 2.2 kg, retained 3.8 ± 0.7 kg and excreted 7.4 ± 1.5 kg N/doe/year. Nitrogen excretion estimated in this work can be considered as representative of some of the main animal production systems of the North-East of Italy. These values should not be considered as fixed, otherwise the implementation of the various strategies to reduce N excretion would not be possible. They should be considered as guidelines in the assistance both to public institutions and private enterprises in the evaluation of N excretion at farm level, favouring a more accurate quantification of the excretions, an increase of N retention efficiency and a better knowledge of the requirements of agricultural land. Moreover, a major extension of the agricultural land to be fertilised with manure should be promoted.

Effects of low-protein diets and rumen-protected conjugated linoleic acid on production and carcass traits of growing double-muscled Piemontese bulls.

The effects of low-protein (LP) diets and rumen-protected CLA on DMI, ADG, carcass traits, and health status of double-muscled Piemontese young bulls were investigated. Forty-eight bull calves (BW = 237 ± 24 kg) were divided in 4 groups and housed in 12 fully slatted pens. Bulls were fed 2 diets differing in CP density [high-protein (HP) diet: CP = 145 g/kg of DM; LP diet: CP = 108 g/kg of DM] and top-dressed with 80 g/d of rumen-protected CLA or 65 g/d of hydrogenated soybean oil. Orts were collected weekly and feed intake was estimated on a pen basis, with 3 replicated pens for each treatment. Each bull was weighed monthly and examined for alterations of the locomotion system by using the locomotion score as an index of lameness and by counting the number of swollen joints. Carcass quality traits were measured at slaughter, after a feeding period of 332 d. Compared with HP, LP reduced ADG only during the first 4 mo of the trial (1.30 vs. 1.53 kg/d, P = 0.003). However, because of compensatory growth, over the whole trial, no significant effects attributable to CP or to additive were found on final BW (668 kg), ADG (1.19 kg/d), DMI (8.50 or 86 g/d per kg of BW(0.75)), dressing percentage (67.3%), carcass conformation (5.2 points), and carcass fat covering (1.87 points). Feed efficiency was affected by a CP × additive interaction (P = 0.030), with CLA improving feed efficiency when added to the LP diets, whereas feed efficiency was reduced with the HP diets. The addition of both LP and CLA reduced the number of bulls presenting swollen joints (P = 0.001), and LP improved the locomotion score (P = 0.021) compared with HP. It was concluded that 10.8 g/kg of CP density in the diet is sufficient for double-muscled Piemontese bulls. The reduction in CP density from 145 to 108 g/kg of DM, in addition to reducing the feeding cost, allows a strong reduction in N consumption without negative consequences on growth performance and carcass traits.

A model to predict water intake of a pig growing in a known environment on a known diet.

A model to predict voluntary water intake (WI) of a pig fed a known diet in a known environment is described. The daily retentions of protein, lipid, water and ash were estimated over time using a published pig growth model. Food intakes were estimated using published methods. WI was estimated by adding the amounts required for digestion (WD), faecal excretion (Wfec), growth (WG), evaporation (WE), urinary excretion (WU) and by then subtracting the water arising from feed (WF), from nutrient oxidation (WO) and synthesis of body constituents (WS). WD was predicted assuming an absorption of water of 0.10, 0.16 and 0.07 kg/kg digestible carbohydrate, crude protein and lipid respectively. Wfec was estimated taking into account the water associated with the undigested protein (0.86 kg/kg), diethyl ether extract (-12.11 kg/kg), crude fibre (1.86 kg/kg), ash (-0.42 kg/kg) and N-free extract (4.4 kg/kg). The basal level of WE was estimated from the heat production of the pig fed ad libitum (MJ/d) as: 0.25 x (metabolizable energy - energy retained as protein and lipid) x 0.4, where 0.25 is the assumed proportion of the insensible heat loss at the comfort temperature and 0.4 is the water lost per MJ dissipated heat. WE in a hot environment was predicted by assuming that evaporation increased up to three times the basal level to offset the decreased sensible heat loss. To predict WU a water requirement for renal excretion of 2.05 and 3.40 kg/osmol excreted N as urea and minerals respectively was assumed. The urinary load of N and minerals was predicted from the intake of digestible nutrients and their retention. From the oxidation of 1 kg carbohydrate, protein, and fat it was assumed that 0.6, 0.42 and 1.07 kg water (WO) were released respectively. WS was predicted by assuming a release of 0.16, 0.07 and 0.57 kg water per kg retained protein, retained lipid coming from digestible lipid, and retained lipid coming from digestible carbohydrate respectively. The model is strongly rooted in a theoretical structure. When its predictions were compared with data from suitable experiments, the results were not significantly different. Both the pattern and the magnitude of responses of the model to changes in body weight, feed intake and environmental temperature are sensible and it allows a fuller prediction of voluntary water intake than the methods currently available.

Effect of dairy farming system, herd, season, parity, and days in milk on modeling of the coagulation, curd firming, and syneresis of bovine milk

The objectives of this study were to characterize the variation in curd firmness model parameters obtained from coagulating bovine milk samples, and to investigate the effects of the dairy system, season, individual farm, and factors related to individual cows (days in milk and parity). Individual milk samples (n = 1,264) were collected during the evening milking of 85 farms representing different environments and farming systems in the northeastern Italian Alps. The dairy herds were classified into 4 farming system categories: traditional system with tied animals (29 herds), modern dairy systems with traditional feeding based on hay and compound feed (30 herds), modern dairy system with total mixed ration (TMR) that included silage as a large proportion of the diet (9 herds), and modern dairy system with silage-free TMR (17 herds). Milk samples were analyzed for milk composition and coagulation properties, and parameters were modeled using curd firmness measures (CFt) collected every 15 s from a lacto-dynamographic analysis of 90 min. When compared with traditional milk coagulation properties (MCP), the curd firming measures showed greater variability and yielded a more accurate description of the milk coagulation process: the model converged for 93.1% of the milk samples, allowing estimation of 4 CFt parameters and 2 derived traits [maximum CF (CF(max)) and time from rennet addition to CF(max) (t(max))] for each sample. The milk samples whose CFt equations did not converge showed longer rennet coagulation times obtained from the model (RCT(eq)) and higher somatic cell score, and came from less-productive cows. Among the sources of variation tested for the CFt parameters, dairy herd system yielded the greatest differences for the contrast between the traditional farm and the 3 modern farms, with the latter showing earlier coagulation and greater instant syneresis rate constant (k(SR)). The use of TMR yielded a greater tmax because of a higher instant curd-firming rate constant (k(CF)). Season of sampling was found to be very important, yielding higher values during winter for all traits except k(CF) and k(SR). All CFt traits were affected by individual cow factors. For parity, milk produced by first-lactation cows showed higher k(CF) and k(SR), but delays in achieving CF(max). With respect to stage of lactation, RCT(eq) and potential asymptotic CF increased during the middle of lactation and stabilized thereafter, whereas the 2 instant rate constants presented the opposite pattern, with the lowest (k(CF)) and highest (k(SR)) values occurring in mid lactation. The new challenge offered by prolonging the test interval and individual modeling of milk technological properties allowed us to study the effects of parameters related to the environment and to individual cows. This novel strategy may be useful for investigating the genetic variability of these new coagulation traits.

Genetic and environmental relationships of detailed milk fatty acids profile determined by gas chromatography in Brown Swiss cows

The aim of this study was to characterize the profile of 47 fatty acids, including conjugated linoleic acid (CLA), 13 fatty acid groups, and 5 Δ(9)-desaturation indices in milk samples from Brown Swiss cows. The genetic variation was assessed and the statistical relevance of the genetic background for each trait was evaluated using the Bayes factor test. The additive genetic, herd-date, and residual relationships were also estimated among all single fatty acids and groups of fatty acids. Individual milk samples were collected from 1,158 Italian Brown Swiss cows and a detailed analysis of fat percentages and milk fatty acid compositions was performed by gas chromatography. Bayesian animal models were used for (co)variance components estimation. Exploitable genetic variation was observed for most of the de novo synthesized fatty acids and saturated fatty acids, except for C4:0 and C6:0, whereas long-chain fatty acids and unsaturated fatty acids (including CLA) were mainly influenced by herd-date effects. Herd-date effect explained large portions of the total phenotypic variance for C18:2 cis-9,cis-12 (0.668), C18:3 cis-9,cis-12,cis-15 (0.631), and the biohydrogenation and elongation products of these fatty acids. The desaturation ratios showed higher heritability estimates than the individual fatty acids, except for CLA desaturation index (0.098). Among the medium-chain fatty acids, C12:0 had greater heritability than C14:0 (0.243 vs. 0.097, respectively). Both C14:0 and C16:0 showed negative additive genetic correlations with the main monounsaturated and polyunsaturated fatty acids of milk fat, suggesting that their synthesis in the mammary gland may be influenced by the presence of unsaturated fatty acids. No correlation was observed between C4:0 and the other short-chain fatty acids (except for C6:0), confirming the independence of C4:0 from de novo mammary fatty acid synthesis. Among the genetic correlations dealing with potentially beneficial fatty acids, C18:0 was positively correlated with vaccenic and rumenic acids and negatively with linoleic acid. Finally, fatty acids C6:0 through C14:0 showed relevant correlations due to unknown environmental effects, suggesting the potential existence of genetic variances in micro-environmental sensitivity. This study allowed us to acquire new knowledge about the genetic and the environmental relationships among fatty acids. Likewise, the existence of genetic variation for most of de novo synthetized fatty acids and saturated fatty acids was also observed. Overall, these results provide useful information to combine feeding with genetic selection strategies for obtaining a desirable milk fatty acids profile, depending on the origin of fatty acids in milk.

A methodological approach to assess nutrient requirements of heavy pigs in Italy

Abstract This paper reports the results of the work of the “Nutrient requirements of heavy pigs” ASPA Commission. The Commission work was mainly focused on the problem of identifying a good and flexible methodology for establishing nutrient requirements of heavy pigs in Italy, in a situation where the major part of the pigs are used for ham and other typical products. Nutrient allowance was considered to be a variable open to manipulation, since its optimal definition depends on the specific circumstances of each single production unit. It appeared that the most logical way to account for the many interactions involved was to integrate available information using computer simulation techniques. A methodology based on the following steps was proposed and analyzed: i) selection of a mathematical model to describe the chemical growth of pigs over time as result of the interactions of genotype, feed and climate; ii) developing suitable equations to predict the quality parameters of the carcass and, if possible, of the single cuts from the body’s chemical status and implementation of these equations in the model; iii) identification of production targets and use of the model as a tool to simulate the effect of different genotypes, feed and climate on the productive and the economic results. A model strongly rooted in a theoretical framework, simple enough to be applied in practice and requiring a limited number inputs was selected from literature. From a preliminary evaluation, performed by using experimental calorimetric data, it was concluded that the model was potentially able to accurately predict the chemical growth of pigs under different conditions of feeding and climate. The major lack of knowledge regarded the values of genotypic descriptors of the national pig populations, the evaluation for which some simple experimental protocols are described in literature. Other lack of knowledge involved relationships to predict the anatomical growth and the evolution of quality parameters of carcass and cuts from the chemical composition of the body. If a correlation between the chemical composition of the pig’s body and production targets is confirmed, then a link between the farmer and the industry can be established and the model could be used to identify more convenient feeding strategies. The conceptual basis and the way to assess nutrient requirements of heavy pigs have been clearly identified.

Technical note: In vitro total gas and methane production measurements from closed or vented rumen batch culture systems

This study compared measured gas production (GP) and computed CH4 production values provided by closed or vented bottles connected to gas collection bags. Two forages and 3 concentrates were incubated. Two incubations were conducted, where the 5 feeds were tested in 3 replicates in closed or vented bottles, plus 4 blanks, for a total of 64 bottles. Half of the bottles were not vented, and the others were vented at a fixed pressure (6.8 kPa) and gas was collected into one gas collection bag connected to each bottle. Each bottle (317 mL) was filled with 0.4000 ± 0.0010 g of feed sample and 60 mL of buffered rumen fluid (headspace volume = 257 mL) and incubated at 39.0°C for 24 h. At 24 h, gas samples were collected from the headspace of closed bottles or from headspace and bags of vented bottles and analyzed for CH4 concentration. Volumes of GP at 24 h were corrected for the gas dissolved in the fermentation fluid, according to Henrys law of gas solubility. Methane concentration (mL/100mL of GP) was measured and CH4 production (mL/g of incubated DM) was computed using corrected or uncorrected GP values. Data were analyzed for the effect of venting technique (T), feed (F), interaction between venting technique and feed (T × F), and incubation run as a random factor. Closed bottles provided lower uncorrected GP (-18%) compared with vented bottles, especially for concentrates. Correction for dissolved gas reduced but did not remove differences between techniques, and closed bottles (+25 mL of gas/g of incubated DM) had a greater magnitude of variation than did vented bottles (+1 mL of gas/g of incubated DM). Feeds differed in uncorrected and corrected GP, but the ranking was the same for the 2 techniques. The T × F interaction influenced uncorrected GP values, but this effect disappeared after correction. Closed bottles provided uncorrected CH4 concentrations 23% greater than that of vented bottles. Correction reduced but did not remove this difference. Methane concentration was influenced by feed but not by the T × F interaction. Corrected CH4 production was influenced by feed, but not by venting technique or the T × F interaction. Closed bottles provide good measurements of CH4 production but not of GP. Venting of bottles at low pressure permits a reliable evaluation of total GP and CH4 production.

Quality traits and modeling of coagulation, curd firming, and syneresis of sheep milk of Alpine breeds fed diets supplemented with rumen-protected conjugated fatty acid

The aim of this study was to test the modeling of curd-firming (CF) measures and to compare the sheep milk of 3 Alpine breeds supplemented with or without rumen-protected conjugated linoleic acid (rpCLA). Twenty-four ewes of the Brogna, Foza, and Lamon breeds were allotted to 6 pens (2 pens/breed) and fed a diet composed of corn grain, corn silage, dried sugar beet pulp, soybean meal, wheat bran, wheat straw, and a vitamin-mineral mixture. The rpCLA supplement (12 g/d per ewe plus 4 g/d for each lamb older than 30 d) was mixed into the diet of 1 pen per sheep breed (3 pens/treatment) to provide an average of 0.945 and 0.915 g/d per ewe of the cis-9,trans-11 C18:2 and trans-10,cis-12 C18:2 conjugated linoleic acid isomers, respectively. The trial started at 38 ± 23 d after parturition, and individual morning milk samples were collected on d 16, 23, 37, 44, and 59 of the trial. Milk samples were analyzed for composition, and duplicate samples were assessed for milk coagulation properties (MCP). A total of 180 CF measures for each sample (1 every 15s) were recorded. Model parameters were the rennet coagulation time, the asymptotic potential CF, the CF instant rate constant, the syneresis instant rate constant, the maximum CF achieved within 45 min (CFmax), and the time at achievement of CFmax. The data were analyzed using a hierarchical model that considered the fixed effects of breed, diet, lamb birth, and initial days in milk, which were tested on individual ewe (random) variance; the fixed effect of sampling day, which was tested on the within-ewe sample (random) variance; and the fixed effect of instrument or cuvette position (only for MCP), which was tested on the residual (replicates within samples) variance. The local Alpine sheep breeds displayed similar milk compositions, traditional MCP, and CF modeling parameters. Supplementation with rpCLA triggered changes in milk composition and worsened MCP (e.g., delayed rennet coagulation time, slower CF instant rate constant, and a doubling of syneresis instant rate constant), but did not influence potential CF. Overall, our results indicate that rpCLA supplementation reduced the actual maximum CF (CFmax) but did not modify the interval between rennet addition and CFmax or time to CFmax.

Room air stratification in combined chilled ceiling and displacement ventilation systems

Radiant chilled ceilings with displacement ventilation (DV) represent a promising integrated system design that combines the energy efficiency of both sub-systems with the opportunity for improved ventilation performance resulting from the thermally stratified environment of DV systems. The purpose of this study was to conduct laboratory experiments for a typical U.S. interior zone office to investigate how room air stratification is affected by the ratio of cooling load removed by a chilled ceiling to the total cooling load, η, for two different chilled ceiling configurations. The experiments were carried out in a climatic chamber equipped with radiant panels installed in the suspended ceiling. In the first test configuration representative of thermally activated slab applications, 12 panels covering 73.5% of the ceiling were used. During the second series of tests, 6 panels covering 36.7% of the ceiling were used, representing a typical installation of metal radiant panels. The cooling load removed by the panels varied between 0 and 73 W/m2 (0–23.1 Btu/(h ft2)) (based on radiant panel area) or between 0 and 28 W/m2 (0–8.9 Btu/(h ft2)) (based on room area). The average mean water temperature of the panels varied over a more moderate range of 20°C–24°C (60°F–75.2°F) for the 12-panel tests and over a colder range of 16.5°C–22.6°C (61.7°F–72.7°F) for the 6-panel tests. The displacement ventilation airflow rate varied between 1.65 and 4.03 l/(s m2) (0.32–0.79 cfm/ft2), and the supply air temperature was kept constant at 18°C (64.4°F). The results showed that increasing η, the relative amount of the cooling load removed by the chilled ceiling, reduced the total room stratification. However, a comparison between the colder 6-panel tests and the warmer 12-panel tests indicated that average radiant surface temperature (mean chilled water temperature in panels) was a stronger predictor of stratification performance. When smaller active radiant ceiling areas are used (e.g., for a typical radiant ceiling panel layout), colder radiant surface temperatures are required to remove the same amount of cooling load (as a larger area), which cause more disruption to the room air stratification. Despite the impact that the chilled ceiling has on stratification, the results indicate that a minimum head–ankle temperature difference of 1.5°C (2.7°F) in the occupied zone (seated or standing) will be maintained for all radiant ceiling surface temperatures of 18°C (64.4°F) or higher.

Effect of proteinate or sulphate mineral sources on trace elements in blood and liver of piglets

Four hundred piglets were housed in 20 pens and offered for 42 days a pre-starter and then a starter compound supplemented with trace elements given as sulphates (SULF) or proteinates (PROT) at a common level (100) or at a reduced level (20) of inclusion. The common level supplied 278, 148, 315 and 98 mg/kg and the reduced level supplied 128, 38, 135 and 50 mg/kg of iron (Fe), copper (Cu), zinc (Zn) and manganese (Mn), respectively, taking into account the natural food contents. Proteinates used in the trial were analysed and described in terms of content and quality of different potential ligands. Piglet growth was not affected by any treatment. At the end of the trial blood samples were collected from eight pigs for each treatment. These animals were slaughtered and their livers were removed, weighed and analysed. Compared with SULF, PROT increased significantly plasma levels of Fe (25·1 v. 15·7 μ mol/l), haemoglobin (10·9 v. 10·4 g/dl) and the number of red blood cells (6·4 v. 6·1 millions per μ l) but the liver recovery of Fe was not affected by any treatment. In piglets receiving PROT the liver content of Cu and Zn increased significantly compared with those receiving SULF. On reducing the dosage, Cu in the liver significantly decreased with SULF but not with PROT and the amount of Zn decreased more with SULF than with PROT. The results may reflect a better availability of Cu and Zn when proteinates rather than sulphates were used as mineral supplements.