Influence of Ascorbic Acid and Glutathione Antioxidants on Frozen-Thawed Canine Semen

Poor sperm viability post-thaw has resulted in constant research into methods of cryopreservation of canine semen. One factor that may be involved in poor viability is sperm oxidative stress caused by excessive formation of reactive oxygen species. The present study was performed in order to evaluate the effect of different concentrations of ascorbic acid (AA) and glutathione (Glu) added to an extender for the freeze-thawing of dog sperm. Semen from five mature dogs was collected and frozen in two studies. Prior to and after freezing, sperm motility, morphology and membrane status were examined. In addition, sperm motility was examined up to 120 min after thawing to evaluate thermo-resistance. In study I, semen was collected twice from each dog. On both occasions, semen was divided into three aliquots: control, Glu 1 m m and Glu 5 m m . In study II, semen was collected twice and divided into three aliquots; control, AA 50 μ m and AA 250 μ m . Initial sperm motility was significantly higher in sperm diluted with AA 50 μ m ; sperm longevity, however, measured by a thermal-resistance test (TRT), was higher for Glu treatments. Higher concentration of Glu produced significant improvement in TRT and membrane status, whereas higher concentration of AA had a negative impact in sperm longevity. Antioxidant supplementation to semen freezing extenders improved semen quality post-thaw. Moreover, Glu had the most beneficial effect when supplemented at 5 m m .     

Development of One vs Multiple Ovulatory Follicles and Associated Systemic Hormone Concentrations in Mares

Ablation of follicles ≥  6 mm in diameter and treatment with PGF2α 10 days after ovulation were used to induce the development of ovulatory waves. Comparisons were made between induced waves with one (33 waves, 72%) and multiple (13 waves, 28%) ovulatory follicles. Diameter deviation was defined as the separation of follicles into dominant and subordinate categories. Multiple ovulatory follicles were preceded by more (p < 0.001) follicles ≥ 20 mm at the beginning of deviation, higher LH preceding deviation (approached significance, p < 0.08), lower (p < 0.05) concentrations of FSH on the day of deviation and thereafter, and higher (p < 0.0003) oestradiol by 2 days after deviation. During the peri-ovulatory period, systemic hormone concentrations for waves with multiple ovulations involved higher oestradiol before ovulation (approached significance, p < 0.07), lower FSH (p < 0.04) before and after ovulation, and both higher progesterone (p < 0.05) and lower LH (p < 0.05) beginning the day after ovulation. Results indicated that by the beginning of deviation there were more follicles ≥  20 mm and subsequently greater oestradiol production in waves that led to the development of multiple ovulatory follicles, and during the peri-ovulatory period differences between one and multiple ovulations were consistent with the negative effects of the ovarian hormones on the gonadotropins.     

饲料浪费意味着营养流失

改进饲养方式和设备的使用,并不是减少养猪场饲料损失的唯一需要考虑的方面。许多猪肉生产者认为,养猪场浪费的饲料仅仅是指喂给猪的那部分饲料,而不是指被消耗的那部分饲料。饲喂器的设计缺陷、料槽破损或地面饲喂通常是导致饲料浪费的罪魁祸首。跳出框框来思考,至于养分流失或没得到正确计算的部分为饲料浪费赋予了新的内涵。     

Effects of extrusion processing of feed ingredients on apparent digestibility coefficients of nutrients for rainbow trout (Oncorhynchus mykiss)

An experiment was conducted to evaluate the effects of extrusion processing on apparent digestibility coefficients (ADCs) of dry matter, crude protein, crude fat, energy and minerals in soya bean meal (SBM), barley, corn gluten meal and whole wheat, using rainbow trout Oncorhynchus mykiss as the test species. In addition, availabilities of amino acids were also determined in SBM. Feed ingredients were preconditioned at 89–93 °C and then extruded using a Wenger X‐85 extruder. Nonextruded ingredients were used as is, meaning that they were not preconditioned. The extruded and nonextruded ingredients were mixed with a casein–gelatin reference diet at 3 : 7 ratio prior to determination of ADC values. A total of 135 trout (initial mean body weight 223.4 ± 12.7 g) were stocked into nine 140‐L fibreglass digestibility tanks with 15 fish per tank. Individual tanks were assigned randomly to each of eight diets made from the four ingredients (extruded and nonextruded) plus the reference diet. After faeces were collected in the first week, the diets were switched among tanks, and faeces were collected again after 5‐day acclimation period in the second week. Yttrium oxide was used as the inert marker. Results showed that extrusion processing significantly improved ADCs of dry matter, crude fat and gross energy, and reduced ADCs of crude protein, phosphorus, copper, iron and zinc. Results also showed that the effects of extrusion processing on chemical composition and ADCs of nutrients depended on the ingredients. It is recommended that trace minerals such as copper, iron and zinc be supplemented by an additional 10–20% when rainbow trout diets are extruded because of their reduced bioavailability in plant meal‐based feed ingredients.