Lysine (Lys) availability in three different soya-bean meal (SBM) products was determined using the following techniques: whole body (WB) net flux of Lys, digestible Lys (duodenal flow × intestinal digestibility) and the plasma Lys response curve method of Rulquin and Kowalczyk (2003). Four multiparous Holstein cows (173 days in milk) were equipped with ruminal and duodenal cannulas and used in a 4 × 4 Latin square experiment with 14-day periods. The animals were fed either solvent-extracted SBM (SE), expeller-processed SBM (EP) or lignosulphonate-treated SBM (LS) at 23% of the diet dry matter (DM). The fourth treatment (SE70) consisted of a continuous infusion of Lys (70 g/day) into the omasum of cows fed the SE diet. Chromium(III) oxide was included as a digesta marker in order to determine the duodenal flow of amino acids (AA). On day 12 of each experimental period, six blood samples were collected to determine plasma Lys concentrations. Immediately after that, a pulse dose of L-[2–15N] Lys was administered in the jugular vein. Jugular blood samples were then collected at 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 13, 16, 19, 25 and 31 min after the injection to determine 15N Lys enrichment. On each of days 13 and 14, eight digesta samples were collected and pooled by period. Amongst the diets of SBM (SE, EP, LS), no differences were observed for duodenal Lys flow or digestible Lys. Duodenal flow of microbial N with SE was numerically higher, compared with EP and LS, indicating enhanced duodenal supply of microbial Lys for this diet, and this may have compensated for the additional Lys derived from undegradable protein in rumen-protected SBM products (EP and LS). The use of the plasma response curve method as well as the measurement of WB Lys flux also revealed no differences in Lys availability among the SBM products. The WB flux method resulted in 100% post-ruminal recovery of the Lys infused with diet SE70 compared with the control diet SE, which indicates that the method is reliable for determining Lys availability. The Lys flux approach not only allows for the estimation of intestinally available essential AA but also it avoids the use of cannulated animals.

Cistus ladanifer L. (CL) is a perennial shrub abundant in dry woods and dry land of Mediterranean zone, with high level of tannins. Tannins bind to protein, preventing its degradation in the digestive compartments. This tannin/protein complex may be advantageous when partially protecting good-quality feed protein from excessive rumen protein degradation. The objective of this trial was to use a CL phenol crude extract to prevent excessive rumen degradation of soya-bean meal protein. The phenolic compounds were extracted using an acetone/water solution (70:30, v/v). Soya-bean meal was then treated with this crude CL extract, containing 640 g of total phenols (TP) per kg of dry matter (DM), in order to obtain mixtures with 0, 12.5, 25, 50, 100 and 150 g of TP per kg DM. Three rumen-cannulated rams were used to assess in sacco rumen degradability of DM and nitrogen (N). The three-step in vitro procedure was used to determine intestinal digestibility. Increasing extract concentrations quadratically decreased the N-soluble fraction a (R2 = 0.96, P = 0.0001) and increased the non-soluble degradable fraction b (R2 = 0.92, P = 0.005). The rate of degradation c linearly decreased with CL extract doses (R2 = 0.44, P = 0.0065). For the effective rumen degradability of N, a linear reduction (R2 = 0.94, P < 0.0001) was observed. The in vitro intestinal digestibility of protein (ivID) quadratically decreased (R2 = 0.99, P < 0.0001) with TP inclusion and the rumen undegradable protein (RUP) showed a quadratic increase (R2 = 0.94, P = 0.0417). Total intestinal protein availability, computed from the RUP and ivID, linearly decreased with TP inclusion level (R2 = 0.45, P = 0.0033).

A 3 X 2 factorial experiment was conducted to investigate the interactions between lactofeed 70 (LF70) (860 g/kg whey permeate, 140 g/kg soya-bean meal; Volac International, UK) and soya-bean meal (SBM) or dried skim milk (DSM) in piglet diets. Three hundred and thirty-six piglets were selected after weaning at 21 days with an initial live weight of 6-35 kg. They were blocked on the basis of live weight and within each block assigned to one of six dietary treatments. The pigs were offered the following starter diets : (1) 300 g/kg LF70 with 215 g/kg SBM and 100 g/kg DSM; (2) 200 g/kg LF70 with 215 g/kg SBM and 100 g/kg DSM; (3) 100 g/kg LF70 with 215 g/kg SBM and 100 g/kg DSM; (4) 300 g/kg LF70 with 325 g/kg DSM; (5) 200 g/kg LF70 with 325 g/kg DSM; (6) 100 g/kg LF70 with 325 g/kg DSM. The starter diets were offered for 25 days. Following this, a weaner diet (14 g/kg lysine, 14-5 MJ/kg digestible energy) was given for a period of 12 days. There was a significant interaction between LF70 level and protein source on average daily gain (ADG P < 0.001) and food conversion ratio (FCR P < 0.05) during the starter period. There was a linear increase in ADG and a linear improvement in FCR with increasing LF70 levels in diets with SBM. However, there was a linear decrease in ADG with increasing LF70 levels in diets with DSM. There was a significant interaction (P < 0.001) between LF70 level and protein source on average daily food intake (ADFI) during the starter period. At high LF70 levels, the inclusion of DSM reduced ADFl compared with SBM. However, there was no difference between DSM and SBM at the medium and low LF70 levels. There was a significant interaction between LF70 level and protein source in organic matter digestibility (OMD) (P < 0.01) and gross energy digestibility (GED) (P < 0.01). The pigs offered diets containing DSM had a significantly lower OMD and GED at low LF70 levels compared with pigs offered diets containing SBM. However, the inclusion of DSM had no significant effect on OMD or GED at the medium and high LF70 levels. There was a quadratic response in nitrogen digestibility (ND) with increasing concentrations of LF70 (P < 0.05). There was an increase in ND to 200 g/kg LF70 inclusion, however there was no further increase in ND above 200 g/kg LF70 inclusion. In conclusion, increasing the inclusion of lactofeed from 100 g/kg to 300 g/kg in starter diets where soya-bean meal comprised the principle protein source improved food efficiency and increased daily gain and daily food intake when compared with diets where dried skim milk comprised the principle protein source.

A 3 ✕ 2 factorial experiment was conducted to investigate the interaction between lactofeed 70 (LF70) (860 g/kg whey permeate, 140 g/kg soya-bean meal, Volac International, UK) levels and soya-bean meal inclusion (SBM) (90 and 225 g/kg) from day 0 to day 25 after weaning (starter period) on growth performance and diet digestibility. A common diet was offered from day 25 to day 38. Dietary treatments were established by substituting LF70 for extruded wheat and soya-bean meal for potato protein (PP) and soya protein concentrate (SPC). Digestible energy and amino acids were maintained by adjusting soya oil and synthetic amino acids. A total of 252 pigs (7·7 kg and 28 ± 2 days of age) were allotted randomly to six treatments containing (1) 0 LF70 with 40 g/kg PP and 40 g/kg SPC and 90 g/kg SBM (2) 0 LF70 with 225 g/kg SBM (3) 175 g/kg LF70 with 40 g/kg PP and 40 g/kg SPC and 90 g/kg SBM (4) 175 g/kg LF70 with 225 g/kg SBM (5) 350 g/kg LF70 with 40 g/kg PP, 40 g/kg SPC and 90 g/kg SBM and (6) 350 g/kg LF70 with 225 g/kg SBM. There was an increase in average daily gain (ADG) (0·182 v. 0·292 v. 0·318 kg, s.e. 0·0089; P < 0·001) and food intake (0·413 v. 0·472 v. 0·489 kg, s.e. 0·0139; P < 0·01) and an improvement in food conversion ratio (FCR) (2·31 v. 1·63 v. 1·55 kg, s.e. 0·037; P < 0·001) as the level of LF70 increased during the starter period. From day 25 to day 38, the pigs given the starter diets containing no LF70 had an improved ADG (P < 0·05) and FCR (P < 0·001) compared with the pigs given 175 and 350 g/kg LF70. The pigs offered diets containing 350 g/kg lactofeed had a significantly higher N digestibility (P < 0·05) than the pigs offered diets containing no lactofeed. There was a significant interaction (P < 0·001) between LF70 and SBM in the apparent digestibility of gross energy (GED). Pigs given higher SBM diets had a higher GED at the 350 g/kg LF70 inclusion than pigs given PP + SPC diets. However, there was no difference in GED at the 0 and 175 g/kg LF70 inclusion. In conclusion, the inclusion of LF70 increased ADG, food intake and apparent N digestibility and improved FCR.

Sixteen early to mid lactation Finnish Ayrshire dairy cows were used in a cyclic change-over experiment with four 21-day experimental periods and a 4 5 2 factorial arrangement of treatments to evaluate the effects of heat-treated rapeseed expeller and solvent-extracted soya-bean meal protein supplements on animal performance. Dietary treatments consisted of grass silage offered ad libitum supplemented with a fixed amount of a cereal based concentrate (10 kg/day on a fresh weight basis) containing 120, 150, 180 or 210 g crude protein (CP) per kg dry matter (DM). Concentrate CP content was manipulated by replacement of basal ingredients (g/kg) with either rapeseed expeller (R; 120, 240 and 360) or soya-bean meal (S; 80, 160 and 240). Increases in concentrate CP stimulated linear increases (P < 0·05) in silage intake (mean 22·5 and 23·8 g DM per g/kg increase in dietary CP content, for R and S, respectively) and milk production. Concentrate inclusion of rapeseed expeller elicited higher (P < 0·01) milk yield and milk protein output responses (mean 108 and 3·71 g/day per g/kg DM increase in dietary CP content) than soya-bean meal (corresponding values 62 and 2·57). Improvements in the apparent utilization of dietary nitrogen for milk protein synthesis (mean 0·282 and 0·274, for R and S, respectively) were associated with higher (P < 0·05) plasma concentrations of histidine, branched-chain, essential and total amino acids (35, 482, 902 and 2240 and 26, 410, 800 and 2119 µmol/l, respectively) and lower (P < 0·01) concentrations of urea (corresponding values 4·11 and 4·52 mmol/l). Heat-treated rapeseed expeller proved to be a more effective protein supplement than solvent-extracted soya-bean meal for cows offered grass silage-based diets.

The availability of lysine and the ileal digestibility of amino acids in three cottonseed meals and a soya-bean meal for grower/finisher pigs were determined. The usefulness of the availability estimates for formulating diets was assessed. The availability of lysine, as assessed with a slope-ratio assay, was (proportion of total): cottonseed meal no. 1, 0.27; no. 2, 0.30, no. 3, 0.29; soya-bean meal, 0.90. Heal digestibility of lysine in the meals (proportion of total) was: cottonseed meal no. 1, 0.58; no. 2, 0.68; no. 3, 0.72; soya-bean meal, 0.89. Pigs given diets formulated to the same available lysine concentration grew at similar rates and retained the same amount of lysine in the carcasses. The results indicate that, for meals of high availability (soya-bean meal), reduced ileal digestibility appears to be the main reason for reduced availability. However, in meals of low availability (cottonseed meal), reduced ileal digestibility only accounts for part of the reduced availability. Thus, the ileal digestibility of lysine is not a reliable indicator of lysine availability.