Nutritional evaluation of sunflower products for poultry as affected by the oil extraction process.

The nutritional value of sunflower seed (SFS) products was determined in two experiments using 180 adult Leghorn-type roosters (Hy-Line). In Experiment 1, press and solvent SFS oils were included in a basal diet at four graded levels (from 1.3 to 20%). Each diet was force-fed (30 g) to 10 roosters to determine their TMEn and true fat digestibility. Dietary TMEn and true digestible fat increased linearly (P < 0.0001) with oil inclusion. There were no differences in nutritional value between oils; their digestibility was 90%, which led to 8,385 +/- 39 kcal TME/kg DM. In Experiment 2, the effect of oil extraction on TMEn, true fat, and amino acid digestibility (TAAD) of SFS products was studied. Several products were derived from the oil extraction process: SFS, press extracted SFS (PESFS), and SFS meal (SFSM), as well as recombined products (mix of meal and oil) of SFS and PESFS, and were force-fed directly to 10 roosters each. Oil extraction produced a decrease (P < 0.0001) in true fat digestibility, TAAD, and TMEn (4,555, 2,591, and 1,754 +/- 59 kcal/kg DM for SFS, PESFS, and SFSM, respectively). Digestible fat content explained the difference between TME, of SFS and PESFS, whereas the difference between the TMEn of PESFS and SFSM was lower than expected. Recombined and original products had similar (P > 0.05) TMEn, despite solvent oil showing higher digestibility when released. Recombined SFS showed lower (P < 0.005) TAAD than original SFS (84.2 and 90.4%, respectively), indicating protein damage caused by heat and mechanical pressure. However, there were no differences, except for lysine, in TAAD between original and recombined PESFS (86.3 and 86.6%, respectively); both feeds showed higher (P < 0.05) TAAD than SFSM (83.9%), which indicates a positive effect of fat addition at this step.

Nutritional evaluation of sunflower seed and products derived from them. Effect of oil extraction.

1. Apparent MEn and oil digestibility of hulled sunflower seed (SFS) and the products derived from the oil extraction process: press extracted SFS (PESFS), sunflower seed meal (SFSM), and press and solvent oils (PO and SO) were determined with 198 cockerels. Recombined products (mix of meal and oil) were also evaluated to study the effect of the 2 consecutive oil extraction steps. Each foodstuff was included in a basal diet, according to the proportions resulting from processing, at 100, 200, and 300 g SFS/kg. 2. Dietary energy value and digestible fat content were linearly related to rate of inclusion of test ingredients. Extrapolation values for AMEn (MJ/kg DM) were: SFS, 16.20; PESFS, 9.46; SFSM, 7.62. A decreasing quadratic trend was also found in the AMEn of PESFS, with interpolation values ranging from 11.77 to 9.33 MJ/kg DM between 70 and 210 g/kg DM of inclusion. No differences were observed between PO and SO. The AMEn of of sunflower oil, calculated from its digestibility, was 33.70 MJ/kg DM. 3. The oil extraction process affected the nutritional value of sunflower products. Recombined materials showed greater values than original foodstuffs: R-SFS, 17.47; R-PESFS, 11.49 MJ/kg DM. The increase in oil digestibility (from 0.814 to 0.862 g/kg DM in SFS; from 0.778 to 0.892 in PESFS) accounted for most of the increase observed in AMEn values. 4. As the form in which oil is incorporated in diets (released or within SFS or PESFS) affects the utilisation of sunflower products, their nutritional value is less than maximal and should not be calculated from their ingredients. Solvent oil seems to be the less available fraction of sunflower oil within SFS as the effect of the 2nd extraction proved to be greater than that of the previous press extraction.

Plasma estradiol-17beta levels and gonadosomatic index in tench (Tinca tinca L.) reared in natural and controlled conditions.

The plasma estradiol-17beta levels (E2-17beta) and gonadosomatic index (GSI) of female tench (Tinca tinca L.) reared outdoors and indoors were studied from December 1996 to April 1997. Water temperature and daylight were gradually increased (from 10 to 25 degrees C and from 9 to 16 hours per day, respectively) in the indoor group. Animals reared in natural conditions had similar plasma levels throughout the experiment but animals under controlled conditions experienced an increase in these levels in March in relation to previous months (4.81+/-0.73 ng/ml in March vs. 0.29+/-0.03 ng/ml and 0.99+/-0.31 ng/ml in January and February, respectively; P < 0.05) and in relation to animals reared outdoors (4.81+/-0.73 ng/ml vs. 0.47+/-0.19 ng/ml, respectively; P < 0.05). In April, a sharp decrease in estradiol-17beta in these animals was observed, probably associated with the end of vitellogenesis. GSI increased in both groups through the experiment and indoor animals showed greater values in March vs outdoor fishes (7.57+/-2.18 vs. 4.05+/-0.63; P < 0.05). No significant correlation was found between E2-17beta and GSI, (r = 0.35). It is concluded that manipulation of the photoperiod and temperature can modify gonadal development in tench, and this is similar to the situation in other Teleostei species. This research is the first step towards achieving, out of season, spawning in tench.

Effect of chemical composition of sunflower seed meal on its true metabolizable energy and amino acid digestibility.

The effect of chemical composition of sunflower seed meal (SFSM) on TMEn and true amino acid digestibility (TAAD) was studied. In Experiment 1, the excretion pattern of three SFSM samples force-fed (30 g) to 10 adult cockerels (Hy-Line) each was followed for 84 h to determine the time interval for complete excretion of SFSM. Type of SFSM did not affect the excretion pattern of DM and energy (P=0.438, and P=0.189, respectively). Dry matter and energy excreted every 12 h decreased linear and quadratically (P < 0.001) with collection time. No differences were found from 48 h collection time on. So, an excreta collection period of 48 h was considered adequate for determining the TMEn of SFSM. In Experiment 2, 135 adult cockerels were force-fed to determine the TMEn of 11 samples of SFSM. Type of SFSM affected TMEn (P < 0.001), which ranged from 1,558 to 2,023 kcal/kg DM for SFSM of 31 to 42% CP, respectively. The TMEn was highly correlated (P < 0.001) to hemicellulose (r=-0.90), acid detergent lignin (r=-0.84), neutral detergent fiber (r=-0.82), and CP (r=0.77). Four prediction equations are proposed, the most practical being: TMEn (kcal/kg DM)=2,816.8 - 109.5 hemicellulose (%DM), RSD=70.2. Three out of the 11 samples of SFSM were selected for determining TAAD and the effect of endogenous amino acid correction. The methodology used was that of the TMEn assay, but one more estimation of amino acid endogenous excretion was made using a N-free diet with 85% cornstarch and 15% cellulose. Endogenous amino acid excretion was greater for roosters fed the N-free diet than those deprived of feed, resulting in a higher digestibility (from 0.7 to 2.7%, P < 0.05) only for six amino acids: threonine, valine, alanine, proline, and aspartic and glutamic acids. No interaction was detected (P=0.94) between type of SFSM and method of estimation of endogenous amino acid excretion. The TAAD of SFSM increased significantly (P < 0.001) with the CP content, total TAAD being 86, 88, and 89% for SFSM of 32, 35, and 37% CP, respectively. Attention should be paid when including high fiber-low protein SFSM in poultry diets to balance its lesser digestible amino acids contribution, mainly in lysine (from 0.77 to 1.06% for SFSM of 32 and 37% CP, respectively).