[Effects of eye exercises on axial eye elongation in junior students].

Objective: To evaluate the association between the eye exercises and one-year axial eye elongation in grade 7 students in Beijing. Methods: Sampling was performed using a multistage random cluster approach, and 1 443 students of grade 7 were selected from 9 middle schools in 6 districts for the baseline survey. Data were collected by questionnaires and axial length measurement. Multiple linear regression analysis was used to evaluate the association between eye exercises and excessive axial eye elongation. Results: Among 1 197 (82.95%) students with complete information, the median (QR) age was 12.00 (1.00) years old, girls accounted for 44.28%, and the median (QR) axial eye elongation was 0.22 (0.18) mm. In the multiple linear regression analysis, the frequency of eye exercises was significantly correlated with excessive axial eye elongation in boys (ß=-0.135, 95%CI:-0.253--0.018) but not in girls (ß=-0.075, 95%CI:-0.207- 0.058) after adjusting for sex, age, body height, the number of myopic parents, time spent outdoors and time spent on reading and writing outside class; while the seriousness of eye exercises was not significantly associated with axial eye elongation in boys (ß=-0.028, 95%CI: -0.114-0.058) and girls (ß=-0.035, 95%CI: -0.134-0.064). Conclusion: The increased frequency of eye exercises is beneficial to control the axial eye elongation in boys in Beijing.

Tannin is a key factor in the determination and prediction of energy content in sorghum grains fed to growing pigs.

This study was conducted to determine and compare the DE and ME content as well as the apparent total tract digestibility (ATTD) of GE in 28 samples of sorghum grain fed to growing pigs and to generate prediction equations for DE, ME, and the ATTD of GE based on chemical analysis. The 28 samples included 8 low-tannin sorghum cultivars (LTS; tannin ≤ 0.16%), 10 medium-tannin sorghum cultivars (MTS: 0.67% ≤ tannin ≤ 0.98%), and 10 high-tannin sorghum cultivars (HTS; 1.11% ≤ tannin ≤ 1.51%) obtained from 9 provinces in China and 3 samples of LTS cultivars were obtained internationally. The 28 diets were formulated to contain 96.9% of 1 of the 28 sorghum grains and 3.1% of vitamins and minerals. Eighty-four barrows (36.5 ± 3.4 kg initial BW) were used in a randomized complete block design conducted during 2 consecutive periods ( = 6 per treatment) with the pigs fed different diets during the 2 periods. For each period, pigs were placed in metabolic crates for a 5-d total collection of feces and urine following 7 d of adaptation to the diets. Among the 28 samples, GE, CP, and ADF content (DM basis) ranged from 4,363 to 4,496 kcal/kg, 8.26 to 13.41%, and 3.26 to 5.78%, respectively. The average tannin content was 0.08, 0.84, and 1.29% in the LTS, MTS, and HTS samples, respectively. The DE and ME content (DM basis) ranged from 3,861 to 3,989 and from 3,784 to 3,905 kcal/kg, respectively, in LTS; from 3,646 to 3,740 and from 3,588 to 3,669 kcal/kg, respectively, in MTS; and from 3,481 to 3,617 and from 3,418 to 3,538 kcal/kg, respectively, in HTS. The mean DE, ME, DE/GE, ME/GE, and ATTD of GE in MTS were less than those in LTS ( < 0.05) and greater than those in HTS ( < 0.05). The correlation coefficients between DE, ME, or the ATTD of GE and tannin content were all -0.96 ( < 0.01). The best-fit equations for DE and ME (kcal/kg DM) for the complete set of 28 sorghum grains were 6,974 - (236 × % tannin) - (43.27 × % ADF) + (24.96 × % CP) - (0.71 × % GE) for DE and 3,973 - (262 × % tannin) - (27.24 × % ADF) for ME. Our results strongly indicate that the DE and ME content of sorghum grains are related to their chemical composition, especially their tannin content. The DE and ME content could decrease by more than 200 kcal/kg when the tannin content is increased by 1% in the sorghum grain. Overall, tannin is a key predictor for the DE and ME content as well as the ATTD of GE in sorghum grains, and the potent antinutritive properties from tannin should not be ignored when sorghum is used as an energy source for pigs.

A new phytase continuously hydrolyzes phytate and improves amino acid digestibility and mineral balance in growing pigs fed phosphorous-deficient diet.

Ten ileal T-cannulated pigs (19.26 ± 1.06 kg) were used to evaluate the effects of a novel phytase on apparent ileal digestibility (AID) of AA and apparent total tract digestibility (ATTD) and hindgut disappearance of DM, GE, CP, crude fiber, NDF, and ADF as well as minerals balance. Pigs were fed in a duplicated 5 × 4 incomplete Latin square design (5 diets with 4 periods). Each period consisted of a 5-d adjustment period followed by a 3-d total collection of feces and urine and then a 2-d collection of ileal digesta. The 5 diets included a P-deficient basal diet (0.43% Ca and 0.38% total P) that was supplemented with 0 (negative control [NC]), 500, 1,000, or 20,000 phytase units (FTU)/kg phytase and a positive control (PC) diet that was P adequate (0.64% Ca and 0.52% total P). The addition of phytase to the NC diet improved ( < 0.05) AID of phytate from 11.1 to 62.8, 70.6, and 90.5% at the inclusion rates of 500, 1,000, and 20,000 FTU/kg, respectively. In general, phytase supplementation at a dose of 20,000 FTU/kg further increased ( < 0.05) AID of Ca, total P, and phytate and reduced ( < 0.05) the ileal phytate concentration compared with diets with 500 or 1,000 FTU/kg phytase. Pigs fed the diet with 20,000 FTU/kg phytase but not diets with 500 and 1,000 FTU/kg phytase showed improved ( < 0.05) ATTD of CP and AID of DM, GE, CP, Leu, Lys, Thr, Val, Asp, and Ser compared with pigs fed the PC or NC diet. However, hindgut disappearance of crude fiber and NDF ( < 0.05) were reduced in pigs fed the diet with 20,000 FTU/kg phytase compared with pigs fed the PC or NC diet. Pigs fed diets with 500 or 1,000 FTU/kg phytase had greater ATTD and retention of Ca and P than pigs fed the NC diet but less compared with pigs fed the diet with 20,000 FTU/kg phytase. Supplementation of 20,000 FTU/kg phytase to the NC diet improved ( < 0.05) digestibility of Na, Mn, and Zn as well as retention (%) of Zn. Increasing phytase supplementation doses from 0 to 1,000 FTU/kg linearly improved ( < 0.05) retention of Mg; meanwhile, digestibility of Mg and Mn and AID of Thr showed a linear increase trend ( = 0.084). In conclusion, supplementation of the novel phytase at doses up to 20,000 FTU/kg hydrolyzed most of the phytate (90%) and consequently further improved mineral and protein utilization.

Effect of L- or DL-methionine Supplementation on Nitrogen Retention, Serum Amino Acid Concentrations and Blood Metabolites Profile in Starter Pigs.

The objective of the current study was to evaluate the effect of supplementation of either L-methionine (L-Met) or DL-methionine (DL-Met) to diets of starter pigs on nitrogen (N) balance, metabolism, and serum amino acid profile. Eighteen crossbred (Duroc×Landrace×Yorkshire) barrows weighing 15.45±0.88 kg were randomly allotted to 1 of 3 diets with 6 pigs per treatment. The diets included a basal diet (Met-deficient diet) containing 0.24% standardized ileal digestibility Met with all other essential nutrients meeting the pig's requirements. The other two diets were produced by supplementing the basal diet with 0.12% DL-Met or L-Met. The experiment lasted for 18 days, consisting of a 13-day adaptation period to the diets followed by a 5-day experimental period. Pigs were fed ad libitum and free access to water throughout the experiment. Results showed that the supplementation of either L-Met or DL-Met improved N retention, and serum methionine concentration, and decreased N excretion compared with basal diet (p<0.01). The N retention of pigs fed diets supplemented with the same inclusion levels of DL-Met or L-Met were not different (p>0.05). In conclusion, on equimolar basis DL-Met and L-Met are equally bioavailable as Met sources for starter pigs.

Effects of Coated Compound Proteases on Apparent Total Tract Digestibility of Nutrients and Apparent Ileal Digestibility of Amino Acids for Pigs.

Two experiments were conducted to evaluate effects of coated compound proteases (CC protease) on apparent total tract digestibility (ATTD) of nitrogen (N) and energy, and apparent ileal digestibility (AID) of amino acids (AA) and nutrients in diets for pigs. In Exp. 1, 12 crossbred barrows (initial body weight: 20.14±1.71 kg) were housed in individual metabolism crates and allotted into 2 treatments with 6 piglets per treatment according to weight in a randomized complete block design. The 2 diets were corn-soybean meal basal diets with (0.2 g/kg) or without CC protease supplementation. The CC protease supplementation increased (p<0.05) the digestible and metabolizable N and energy values and the digestibility and retention rate of N in the diet. The ATTD of energy and nutrients had been improved (p<0.05) in the diet supplemented with CC protease. In Exp. 2, 12 crossbred barrows (initial body weight: 20.79±1.94 kg), fitted with T-cannulas at the distal ileum, were blocked by body weight into 2 groups with 6 pigs each. The diets were the same as those in Exp. 1. The CC protease increased (p<0.05) the AID of crude protein and some essential AA including arginine, isoleucine and leucine. The AID and ATTD of energy and nutrients had been improved (p<0.05) by supplemental CC protease, but the hindgut digestibility of nutrients was unaffected. Overall, the CC protease improved the ATTD of N and energy and AID of some indispensible AA and nutrients in the corn-soybean meal diet for pigs. Therefore, the CC protease supplement could improve the utilization of protein in the corn-soybean meal diet and thus contribute to lower N excretion to the environment.