Piero Susmel

Nitrogen balance and partitioning of some nitrogen catabolites in milk and urine of lactating cows

After calving, two groups of four cows were fed fescue hay (10 kg/d) and a concentrate (8 kg/d) containing 0 or 20 g kg−1 urea in order to induce different rumen microbial growth: the partition between the urine and milk excretion of allantoin, uric acid, creatinine and urea was examined. After 21 d of lactation, individual feed intakes, total faeces and urine output and milk yield were recorded for five consecutive days and these measurements were repeated three times at 21-d intervals. In comparison with the control, the urea-supplemented diet had higher apparent digestibility of DM (697 vs. 662 g kg−1, P < 0.05), OM (718 vs. 681 g kg−1, P < 0.05), NDF (600 vs. 542 g kg−1, P < 0.01) and crude protein (631 vs. 497 g kg−1, P < 0.01). The urea-supplemented diet caused higher (P < 0.01) outputs of N in the milk (91 vs. 75 g d−1) and urine (72 vs. 34 g d−1) and a moderate amount was retained (+24 g d−1), while in the control diet the N balance was negative (−3 g d−1). The inclusion of urea caused a significantly (P < 0.01) higher urinary output of allantoin (11.3 vs. 9.3 g N d−1) and urea (44.1 vs. 4.7 g N d−1), while no dietary effects were detected for uric acid or creatinine. The allantoin and uric acid excretion in milk was not significantly higher for the cows receiving urea, which had higher outputs of creatinine (90 vs. 71 mg Nd−1, P < 0.05) and urea (1559 vs. 507 mg N d−1, P < 0.01). The ratio between the quantitative excretion in urine and milk of allantoin, uric acid and creatinine (10.7, 10.2 and 68.7, respectively) did not differ between dietary treatments, while the urine/milk urea excretion ratio had a significant interaction between dietary treatments and periods.

Digestibility and allantoin excretion in cows fed diets differing in nitrogen content

Eight lactating cows were offered 20 kg d−1 hay and 8 kg d−1 concentrate; four of the cows received concentrate containing 20 g kg−1 urea. After 21 d in lactation, individual feed intakes, total faeces and urine output and milk production were recorded for 5 consecutive days and these measurements were repeated 3 times at 21 day intervals. There was no significant difference in DM intake between dietary treatments. Dietary DM in the diet containing urea was significantly more digestible (697 vs. 662 g.kg−1 DM, P < 0.05). About 47% of the additional NPN intake was lost in the urine and the remainder was partitioned between milk (20%) and body retention (33%). These latter two fractions indicate that the additional dietary N was partially captured by rumen microorganisms and metabolised by the host. Allantoin output was significantly (P < 0.01) higher in the cows receiving dietary urea. In conclusion, more urinary allantoin was excreted by cows receiving the diet that was expected to induce higher microbial synthesis.

Rumen fermentation characteristics and digestibility of cattle diets containing different whey:maize ratios

Three experimental diets were formulated to contain the same amount of fescue hay (560 g kg−1 dry matter (DM) Festuca arundinacea) and differing condensed rennet whey:maize meal ratios (0:100, 50:50 and 100:0 on a DM basis, diets M, MW and W, respectively). The diets were fed during two experimental periods to six rumen fistulated, non lactating Simmental cows (average level of intake: 77 g DM kg−1 LW0.75, four cows per treatment). Whey used alone caused a lower rumen pH at 1.5 and 3.0 h after the morning meal (P < 0.01) in comparison with the other two diets, while after 4.5 h rumen acidity values were similar between diets. After feeding, the inclusion of whey led to regular increases (P < 0.05) in the concentrations of propionic acid at 1.5 h (12.4 mmol, 18.3 mmol and 23.8 mmol l−1, respectively for M, MW and W diets), while at 3.0 h the W diet remained significantly higher than the other two (22.1 mmol vs. 14–14.2 mmol l−1, P < 0.01). This was also the case for butyric acid where higher (P < 0.01, 1.5 h) levels were observed for diets containing whey (11.6 and 13.3 mmol vs. 7.9 mmol l−1). The dry and organic matter in the W and MW diets were 3 percentage points (P < 0.05) more digestible than the M diet. The soluble cell content fraction digestibility regularly and significantly increased (P < 0.05) as whey substituted maize (from 749 to 814 g kg−1). The inclusion of whey caused an increase in rumen liquid turnover rate (from 7.1 to 13.4–12.3% h−1, P = 0.058) and enhanced levels of urinary volume which almost doubled in diets containing whey (from 78 to 132–138 mg kg−1 LW0.75, P < 0.05). Urinary allantoin output did not differ between dietary treatments while higher urinary outputs of uric acid were found for cows fed diets containing whey (2.39–2.58 g vs. 1.36 g day−1, P < 0.05).

N losses, purine N derivatives excretion and intestinal digestible protein requirements of cows at maintenance

Three rumen fistulated Simmental cows were fed 4 diets (in 4 experimental periods) obtained by substituting part of the basal fescue hay diet (8 kg/d/cow) with extracted soyabean meal (0, 50, 100 and 150 g/kg hay). Including the soyabean meal gave a range of nitrogen (N) intake from 508 to 1448 mg/kg LW0.75/d and of intestinal digestible protein (PDI) from 2.2 to 6.0 g/kg LW0.75/d. The regression of the apparently digested N (y) with the dietary N content (x) was highly significant (r=0.99; P <0.001) and the intercept obtained (−4.25 g N/kg DM) represents the theoretical metabolic loss with zero dietary N. The intercept of the regression between N balance (y) and ingested N (x) (−311 mg N/kg LW0.75/d; r=0.68; P< 0.05) represents an estimate of total endogenous N losses (urinary and faecal). The maintenance requirement for PDI estimated at N equilibrium (3.88 g PDI/kg LW0.75) was slightly higher than the value adopted by INRA (1988). Urinary purine derivatives N excretion was highly correlated (r=0.85; P< 0.001) with the estimated rumen microbial digestible true protein.

A new approach in association study of single nucleotide polymorphism of genes for carcass and meat quality traits in commercial pigs

Abstract Six batches of four commercial hybrids of heavy pigs, reared for the production of Italian dry-cured hams, were identified for having homogeneous feeding and farm conditions. For a total of 235 pigs, slaughtered in the same slaughterhouse, carcass traits and muscle composition were measured. The pigs were genotyped for single nucleotide polymorphisms (SNPs) of Na+, K+-ATPase subunit alpha 2 (ATPase, Na+/K+ transporting, alpha 2 (+) polypeptide; ATP1A2), cystatin B (CSTB), mitochondrial 2,4-dienoyl-CoA reductase 1 (DECR1), leptin (LEP; 3 SNPs), melanocortin receptor 4 (MC4R), melanocortin receptor 5 (MC5R), sarcolipin (SLN) and titin (TTN) genes. All genes showed biallelic polymorphisms and the alleles were differently distributed between the six batches. Pigs were subsequentely clustered in “lean” and “fat” using either carcass traits (lean percentage, backfat thickness, loin muscle thickness, ham weight and ham cover fat thickness: 100 lean and 135 fat) or meat composition data (dry matter, protein, fat and ash of Biceps femoris and Vastus lateralis and pH after 24 hours: 126 lean and 109 fat). The association of gene polymorphisms with leaness and fatness of pigs was thus investigated using a logistic regression. ATP1A2, LEP (HinfI polymorphism) and MC4R, together with sex and ham weight were, included in the model to screen lean and fat pigs classified according to carcass traits data, yielding a correct classification of 71%. For the lean and fat pigs classified according to muscle composition, sex, CSTB, DECR1, MC5R and LEP (AciI/TaqI polymorphisms) were included in the regression analysis, that yielded a 66% of pigs correctly classified. These preliminary results may indicate that some of the selected candidate genes could be associated to production traits and are worth of further investigations.

Performance of lactating simmental cows fed two diets differing in the content of digestible intestinal protein (PDI)

In each of two trials, two diets differing in intestinal digestible protein (PDI) content (LP: low protein, 70 g kg−1 dry matter; HP: high protein, 120 g kg−1 dry matter) were given to multiparous Simmental cows in early lactation. Effective rumen degradabilities of nitrogen and non-protein dry matter of feed ingredients, estimated by the nylon-bag technique, were used to calculate PDI contents of diets. In trial 1, two groups of six cows were fed, in two successive periods of 7 weeks each, the diets LP and HP allocated according to energy requirements (LPR and HPR). In trial 2, the diets LP and HP were fed in two periods of 6 weeks each to 24 cows (six cows/group) according to energy requirements (LPR and HPR) or ad libitum (LPL and HPL). In trial 1, total and energy-corrected milk (ECM) yields were significantly higher (P < 0.01) for cows receiving diet HPR (20.7 and 19.2 vs. 18.9 and 17.4 kg day−1), while milk fat and protein contents were similar. Live weight changes were different between groups (−126 and +39 g day−1 respectively, for LPR and HPR diets) but this difference was not significant. In trial 2, cows fed HPL diets had significantly higher milk yields compared with the LPL and LPR diets (20.0 vs. 17.7 and 17.4 kg day−1, respectively, P < 0.05), but not with the HPR diet (19.0 kg day−1). ECM yield was higher (P < 0.05) for cows receiving more protein both between restricted groups (18.4 vs. 16.4 kg day−1, respectively for HPR and LPR groups) and between ad-libitum groups (18.8 vs. 17.0 kg day−1, respectively for HPL and LPL groups). Milk composition was not affected by dietary treatments. Diets fed according to requirements caused negative, but differing, live weight changes (−783 and −44 day−1 respectively for LPR and HPR diets, P < 0.05). For ad-libitum treatments, LPL cows lost live weight while HPL cows gained live weight (−221 vs. 433 day−1, respectively, P < 0.05). In the present experiments, increasing the supply of dietary PDI improved milk production even if the recycled nitrogen and live weight change could have contributed to protein requirements.

Productive response of Duroc x Large White and Commercial Hybrid x Large White crosses fed high and low protein diets

Thirty five Duroc x Large White (DUxLW) and 43 Commercial Hybrid x Large White (CHxLW) were fed two diets differing for the content of crude protein (CP), with the aim to evaluate the effects of these diets on growth, carcass and thigh traits. Pigs were allotted to two groups and fed high protein (HP) and low protein (LP) diet. Within each dietary group, 3 diets were formulated, for the initial phase of growth (from 79 to 112 days, 17.3% and 15.4% CP as fed basis for the HP and LP diet, respectively), for the intermediated phase of growth (from 113 to 196 days, 15.1% and 13.7% CP as fed basis for the HP and LP diet, respectively) and for the finishing period (from 197 to 272 days, 13.4% and 11.4% CP as fed basis for the HP and LP diet, respectively). HP diets were supplemented with Lysine, LP were supplemented also with Methionine and Threonine. Pigs were slaughtered at nine months of age. Body weight (BW), average daily gain, total feed intake and feed conversion ratio were not affected by diet. Carcass weight, thigh weight, backfat and lean thickness and lean percentage (Fat-O-Meater, FOM) were not affected by dietary treatments, whilst backfat thickness and FOM were significantly higher (P<0.01) in DUxLW and CHxLW pigs genotype respectively. A reduction of about 15% (12% to 17%) of the dietary CP recommended by nutritional requirements does not affect the main productive performances and carcass characteristics of pigs slaughtered at around 160 kg of BW.

Prediction of Purine Derivatives, Creatinine and Total Nitrogen Concentrations in Urine by FT-Near-Infrared Reflectance Spectroscopy (FT-NIR)

The objective of this study was to provide an alternative method for the determination of purine derivatives (PD, which include allantoin, uric acid, hypoxanthine and xanthine), creatinine and total nitrogen (N) concentrations in urine.

The estimation of the rumen rate of passage of dietary NDF from degradability and digestibility data in cows

Abstract The average rumen rate of passage of dietary NDF ( k NDF ) of mixed forage diets for cows was estimated indirectly as the value which, together with the values of kinetic degradation measured for each ingredient under standardised conditions, allowed the calculation of the NDF effective degradability equal to the NDF digestibility. Forages were grown on a permanent grassland divided into equal plots and subjected to three cutting frequencies (two, three and four cuts per year, FC) and two types of fertilisation (slurry only or slurry plus mineral N). Within each FC, the forages from the individual cuts, produced from plots submitted to the same type of N fertilisation, were mixed in proportion to their seasonal yield. Each of these six mixed diets were fed ad libitum to two or three lactating cows (a total of 15 cows), with the proviso that three groups of five cows received the mixtures corresponding to 2, 3 and 4 FC, respectively. Another three similar groups received the same diets supplemented with 25% of dietary dry matter intake (DMI) of concentrate. The cows were kept in stalls and fed the diets for 12 weeks, using the fifth week to measure the dietary NDF digestibility. Samples of forages and concentrate were used to measure the NDF in situ degradability in standardised conditions. The type of grassland fertilisation caused no statistically significant effects. DMI increased with the inclusion of concentrate (111 vs 133 g/kg LW 0.75 , P 0.75 , respectively for 2, 3 and 4 FC, P P k NDF followed the DMI variations, with the highest values in correspondence with the highest DMI: the inclusion of concentrate caused a 25% increase in the estimated k NDF (from 1.49 to 1.84%/h, P k NDF (1.42, 1.56 and 2.03%/h, respectively for FC 2, 3 and 4, P k NDF gave values comparable to those obtained in other experiments with direct measurements and demonstrated the sensitivity of the estimates of k NDF to variations of intake in lactating cows.

Measurement of Purine Derivatives and Creatinine in Urine by HPLC

Two HPLC methods to measure the purine derivatives (PD, including allantoin, uric acid, hypoxanthine and xanthine) and creatinine content in urine are described. PD separation and quantification were achieved using two Spherisorb ODS 2 reversed phase columns connected in series (4.6 × 250 mm) and a Spherisorb ODS 2 Waters pre-column and a Perkin Elmer pump with an auto sampler. The mobile phase was NH4H2PO4:NH4H2PO4-acetonitrile (80:20), which was used at a flow rate of 0.8 ml/min and the detection wavelength was at 190 nm. The average recoveries of standard compounds added to urine samples were satisfactory (92–106%) and the low detection limits (0.7–3.4 µM) permitted the precise determination of these compounds in urine.