以鸭脚稗秸秆和稻草作为粗饲料对杂交奶牛常量和微量营养素利用和产奶量的影响

在印度南部,鸭脚稗秸秆和稻草是主要的粗饲料来源。因此用鸭脚稗秸秆和稻草作为粗饲料饲喂杂交奶牛来研究营养利用率、产奶量和牛奶组成。每组日粮用精料、青饲料和粗饲料以30∶45∶25的比例组成(干物质)。在为期50d的消化试验中,每7d对饲料、饲草、粪便、尿液和奶液混合采样,进行常量和微量营养素的分析。鸭脚稗秸秆含有更高的粗蛋白质、钙、磷、镁、铜、锌和钴,稻草含有更高的酸性洗涤纤维、灰分和无水硅酸。饲喂鸭脚稗秸秆的奶牛干物质、粗蛋白质、粗脂肪、中性洗涤纤维、酸性洗涤纤维和大多微量营养素(钙、磷、镁、锌、铁、锰和钴)的摄入量显著增高,并且,饲喂鸭脚稗秸秆的奶牛对干物质、粗蛋白质、粗脂肪、中性洗涤纤维、酸性洗涤纤维的消化率显著增高,钙、铜、锰、钴的肠道吸收率也显著增高。在每组日粮中,微量营养素都能满足奶牛需要量,但稻草组钙含量(0.40%)低于鸭脚稗秸秆组(0.60%)。鸭脚稗秸秆组的平均产奶量(7.0L/头)高于稻草组(6.3L/头)。奶液组成没有差异,仅有乳脂率(4.7%和4.5%),稻草组偏低。上述结果表明鸭脚稗秸秆是一种优于稻草的粗饲料,当稻草作为唯一的粗饲料饲喂奶牛时,需要额外添加钙来满足产奶需要。     

Adenohypophyseal receptors for LHRH, pituitary content of gonadotropins and plasma concentrations of LH in cyclic, pregnant and postpartum beef cows

Adenohypophyseal concentrations of LHRH receptors, pituitary content of LH and FSH, and plasma concentrations of LH were determined in thirty Hereford, Angus or Hereford-Angus heifers that were randomly assigned by breed and weight to five periods including day 3 of the estrous cycle (CY), pregnant day 120 (P120), 200 (P200), 275 (P275), or day 2 postpartum (PP). Jugular blood samples were collected at 10-min intervals for 8 hr from all cows. Within 2 hr after completion of blood sampling, animals were slaughtered and the pituitary gland frozen at −196 C. LH pulse frequency/8 hr was reduced (P<.05) during gestation (.5, .2, and 1.5 ± .5/8 hr, for P120, P200, and P275, respectively) and PP (.5 ± .5/8 hr) compared to CY (7.8 ± .5/8 hr). Frequency of LH pulses/8 hr was not different (P>.1) among P120, P200 or PP periods but was different (P<.05) between P200 and P275. There were no differences in LH pulse height (P>.1) among periods; however, pulse amplitude was greatest (P<.05) at P120 (1.3 ± .2 ng/ml) and lowest between P200 and PP (.6 to .8 ± .2 ng/ml). Baseline concentrations of plasma LH did not differ (P>.1) among P and PP periods (.3 ± .1 ng/ml), but were lower (P<.05) than in CY animals (.7 ± .1 ng/ml). Concentration of adenohypophyseal LHRH receptors was approximately two-fold greater (P<.05) at P120 (25.85 ± 2.2 fmol/mg) than at all other periods (9.5 to 14.9 ± 2.2 fmol/mg). Pituitary content of LH was greatest at P120 (1.56 ± .11 ug/mg) and lowest (P<.05) at P275 and PP (0.46 to 0.52 ± .11 ug/mg). Pituitary content of FSH was greatest (P<.05) in P (12.7 to 17.0 ± 1.4 ug/mg) and PP (18.3 ± 1.4 ug/mg) vs CY (5.0 ± 1.4 ug/mg) cows and increased from P120 to PP (P<.05). Results indicate that physiological changes occurring during gestation may have an effect on subsequent function of the adenohypophysis in beef cows.     

Descriptive epidemiology of culling in dairy cows from 34 herds in New York State

Data on parity, disease, farmers' stated primary reasons for culling and stage of lactation at diagnosis and at culling were used to describe patterns of culling in Holstein lactations from 34 New York herds. Of 7763 lactations, 18.7% ended in culling [death (95 cows), sales for dairy purposes (104 cows), or slaughter]. The culling rates for specific reasons were: dairy purposes 1.3%, low production 3.8%, reproduction 4.8%, udder problems 4.0%, feet and legs 1.2%, old age 0.3%, accidents 0.3% and miscellaneous reasons 2.9%. Culling increased with parity (at least through Lactation 6) and primarily was due to production, reproduction and udder problems. Culling for these 3 reasons peaked immediately after calving, again between 151 and 240 days post-partum (poor milk production) and at >240 days post-partum (poor reproductive performance). First-lactation cows sold for dairy use tended to be sold in early lactation. Death in older cows usually occurred early in lactation and was due to udder problems or to miscellaneous causes.

Compared to lactations without the disease, lactations with a diagnosis of downer cow, clinical mastitis or treat problems were 3.5, 2.0 and 2.7 times more likely to end in culling, respectively. Among cows diagnosed with a disease and culled, many were culled the same day or within 30 days of the diagnosis. Such “immediate” culling upon diagnosis was especially typical of cows with milk fever, downer cow syndrome, left displaced abomasum, teat problems, and foot and leg problems (and for some cases of clinical mastitis), implying that these disorders led to “forced” culling, which was particularly costly to the farmers.     

Immunological cross-reactivity between pseudocapsular antigens of strains of Staphylococcus aureus isolated from cases of bovine mastitis

An assay was developed to measure the degree of immunological cross-reactivity between the pseudocapsules of a vaccine (reference) strain of Staphylococcus aureus and pseudocapsules of strains of S. aureus isolated from cases of bovine mastitis. The field strains were obtained from Australia, New Zealand, Norway, the U.K. and the U.S.A. There was large variation among strains in cross-reactivity of their pseudocapsules with those of the reference strain. For 104 Australian strains, the range of cross-reactivity indices (CRI) was 6.1-63.2% (on a scale of 0-100%, with 0% being complete identity and 100% being nil identity); for 61 overseas strains the range of CRI values was 25.7-72.1%. The data indicated that pseudocapsule antigens of Australian strains were antigenically more closely related to those of the reference strain than were pseudocapsular antigens of strains from the 4 other countries.     

Continuous Spectrophotometric Assay and Properties of Ascorbic Acid Oxidising Factors in Wheat

A continuous spectrophotometric assay was developed to measure ascorbic acid oxidation in crude Na₂SO₄ extracts of flour. The rate of ascorbic acid oxidation in flour extracts measured using this method was similar to the rate in flour-water suspensions and 2–4 fold less than the rate in dough measured using an indophenol-xylene extraction method. Flour extracts appeared to contain two ascorbic acid oxidising factors; one with optimal activity at pH 6·3 and 30 °C and the other with optimal activity at pH 10 and 40 °C. The pH 6·3 factor had properties similar to those of ascorbate oxidase (EC 1·10·3·3) in its pH and temperature stability, strong inhibition by NaN₃, KCN and diethyldithiocarbamate, inactivation by proteases, and greater stereospecificity towards -ascorbic acid than -isoascorbic acid. The pH 6·3 factor was most concentrated in the pollard milling fraction of wheat and was lowest in flour. The pH 10 factor had several properties indicating non-enzymic oxidation of ascorbic acid; it was not inactivated by proteases, it was inhibited poorly or not at all by the above ascorbate oxidase inhibitors, and it had low specificity for stereoisomers of ascorbic acid.     

小麦品种的耐盐性变化：甜菜碱和乙烯的作用

Four wheat (Triticum aestivum L.) cultivars 711, PBW343, 3765 and WH542 were screened for studying variations in glycinebetaine (GB) content and plant dry mass under 100 mmol L-1 NaCl stress. A tolerance index was calculated using plant dry mass data to select salt-tolerant and salt-sensitive types and find association between tolerance index and GB content. Tolerance index has been used as a good criterion to select the tolerant types under high salinity stress. Further, physiological differences in salt-tolerant cultivar 711 and salt-sensitive cultivar WH542 were examined. The salt-tolerant cultivar exhibited greater GB content, which was found correlative with ethylene. The cultivar also showed higher nitrogen (N) content and nitrate reductase activity, reduced glutathione and higher redox state resulting in maximal protection of plant dry mass than the salt-sensitive type. Thus, the content of GB may be considered as important physiological criteria for selecting salt-tolerant wheat types.     

Paleontological Evidence of Varitions in Length of Synodic Month since Late Cambrian

The values of length of synodic month, obtained from tidally controlled periodical growth patterns in mollusks and stromatolites for several geologic periods, indicate that the deceleration rate of the earth's rotation has not been constant. Two breaks in slope, in the Pennsylvanian and Cretaceous, may be related to changes in distribution of continents, oceans, and adjacent shallow seas.     

Study of electrization of powder skim milk during milk particle movement

Electrization of particles of powder materials is a widely spread phenomenon that makes a practical impact on the functional efficiency of equipment designed for producing a broad range of processed disperse products (dry milk, flour, grain, etc.). The results of electrization tests of powder skim milk particles are presented. A mathematical model of inner and outer transfer of electric charge for a single powder skim milk particle is suggested. The studies on a specialized laboratory unit have made it possible to obtain data on triboelectric charging of particles in different testing conditions.