Formation of the Holocene Lake Chilwa sand bar: Southern Malawi

A sand ridge up to 25 m high separates Lake Chilwa, Malawi, from its former Indian Ocean outlet. Consisting of beach sands capped by dunes, the sand bar was formed by the growth of spits across the northern end of the lake. Mineralogical studies of the sands indicate that they were derived from northern and western areas of the Chilwa basin and were brought to the lake during a period of increased runoff and rainfall intensities. The formation of the sand bar in the early Holocene represented a radical change in the hydrology and biology of Lake Chilwa, from an open fresh water lake to a closed saline lake with a marked tendency to fluctuate in level.     

Goat papillomatosis

The present study indicates that the development of caprine mammary gland warts seems to depend on several factors--namely, nonpigmented skin, adult age, excessive exposure to sunlight, and contact with a yet undefined infective agent. Three types of goat papillomas are described: mammary, cutaneous, other than mammary, and genital. Warts on animals lacking pigmented skin are more frequent in adult animals that live in areas where there is abundant sunlight. Mammary gland papillomas are the most numerous and occur in different stages: ie, goats with mammary gland papillomas that regress, never to recur, goats with papillomas that regress in the winter and reoccur in summer, goats with persistent papillomas of which some are from the group that had previous winter time regression, and goats that have progression of persistent papilloma to carcinoma. Saanen, Saanen crossbreeds, and goats of other breeds that lack pigmented skin and live in sunbelt areas are at high risk for papillomatosis. An infective agent was not defined even after electron microscopic, immunocytochemical, and DNA-DNA hybridization studies. Yet, there is high probability that an infective agent is involved, because mammary gland papillomas usually occur in the susceptible herd 4 to 6 months after an affected goat is introduced.     

Systematics of the nematodes that cause ostertagiasis in cattle, sheep and goats in North America

The systematics of the Ostertagiinae is unsettled with no agreement on how many genera and species are present in cattle and sheep. Ten species of Ostertagiinae are commonly parasitic in cattle and sheep. The males can be identified on the basis of differences in morphology of spicules and genital cones but the females of most species cannot be identified. The species-level systematics have been complicated by the proposal that the ten species are polymorphs of only five species. The systematics at genus level has been complicated by the use of numerous genera for the ten species, at present most commonly Ostertagia, Teladorsagia and Marshallagia. This report (1) describes the current knowledge of the systematics and (2) provides diagnoses of the genera recommended for the ten species. The morphology of the ten species was studied to determine whether characteristics could be found to identify females or to further differentiate the males. Characters studied included the system of longitudinal and surface cuticular ridges (synlophe), the internal morphology of the esophagus and the orientation of rays of the copulatory bursa. The study of species morphology resulted in additional support for the polymorphism proposal. All minor species were found to be identical to their major species in characteristics of the synlophe, esophagus and rays of the copulatory bursa. Two recent classifications of the Ostertagiinae both recommended the use of the genus Teladorsagia for the species T. circumcincta and the two minor species that occur with it, T. trifurcata and T. davtiani. Teladorsagia is characterized by a copulatory bursa in which the five lateral rays are arranged 2-2-1 and a ventral swelling of the genital cone (proconus) is absent. One pair of species, Marshallagia marshalli (major species) and Ostertagia occidentalis (minor species) should be included in the genus Marshallagia. This genus has been characterized by an elongated bursa in which the posterior pair of lateral rays are much longer than the ventral pair. The remaining two pairs of species (O. ostertagi and its minor species O. lyrata, and O. leptospicularis and its minor species O. kolchida) and O. bisonis belong in the genus Ostertagia which is characterized by a 2-1-2 arrangement of the five lateral rays of the copulatory bursa and the presence of a proconus.     

Characterization of feed efficiency traits and relationships with feeding behavior and ultrasound carcass traits in growing bulls

The objectives of this study were to characterize feed efficiency traits and to examine phenotypic correlations between performance and feeding behavior traits, and ultrasound measurements of carcass composition in growing bulls. Individual DMI and feeding behavior traits were measured in Angus bulls (n=341; initial BW=371.1+/-50.8 kg) fed a corn silage-based diet (ME=2.77 Mcal/kg of DM) for 84 d in trials 1 and 2 and for 70 d in trials 3 and 4 by using a GrowSafe feeding system. Meal duration (min/d) and meal frequency (events/d) were calculated for each bull from feeding behavior recorded by the GrowSafe system. Ultrasound measures of carcass 12th-rib fat thickness (BF) and LM area (LMA) were obtained at the start and end of each trial. Residual feed intake (RFIp) was computed from the linear regression of DMI on ADG and midtest BW(0.75) (metabolic BW, MBW), with trial, trial by ADG, and trial by midtest BW(0.75) as random effects (base model). Overall ADG, DMI, and RFIp were 1.44 (SD=0.29), 9.46 (SD=1.31), and 0.00 (SD=0.78) kg/d, respectively. Stepwise regression analysis revealed that inclusion of BW gain in BF and LMA in the base model increased R(2) (0.76 vs. 0.78) and accounted for 9% of the variation in DMI not explained by MBW and ADG (RFIp). Residual feed intake and carcass-adjusted residual feed intake (RFIc) were moderately correlated with DMI (0.60 and 0.55, respectively) and feed conversion ratio (FCR; 0.49 and 0.45, respectively), and strongly correlated with partial efficiency of growth (PEG; -0.84 and -0.78, respectively), but not with ADG or MBW. Gain in BF was weakly correlated with RFIp (0.30), FCR (-0.15), and PEG (-0.11), but not with RFIc. Gain in LMA was weakly correlated with RFIp (0.17) and FCR (-0.19), but not with PEG or RFIc. The Spearman rank correlation between RFIp and RFIc was high (0.91). Meal duration (0.41), head-down duration (0.38), and meal frequency (0.26) were correlated with RFIp and accounted for 35% of the variation in DMI not explained by MBW, ADG, and ultrasound traits (RFIc). These results suggest that adjusting residual feed intake for carcass composition will facilitate selection to reduce feed intake in cattle without affecting rate or composition of gain.     

肉桂精油结合1-MCP对香菇采后褐变和感官品质的影响

以‘808’香菇为试材,研究了1-MCP处理、肉桂精油结合1-MCP处理对香菇采后褐变和感官品质的影响。结果表明:随着贮藏时间的延长,对照组(未处理)香菇感官品质下降,表面L*值降低、褐变严重,开伞度增加;从不同浓度1-MCP处理的保鲜效果来看,与对照(未处理)、0.5 mg·L-1和10.0 mg·L-1 1-MCP相比,2.0 mg·L-1 1-MCP处理保鲜效果最好,菇体开伞少,质地硬度大、色泽好;从肉桂精油结合1-MCP处理来看,以5μL·L-1肉桂精油结合2.0 mg·L-1的1-MCP处理效果最好,延迟了香菇褐变和开伞的发生,维持了香菇表面较高的L*值高,感官得分最高。     

Coastal land scalding in NSW,Australia: soil chemical characteristics and their implications for remediation of the scalded lands

Scalded lands are common in acid sulphate soil areas on the New South Wales coast, Australia. In this work, chemical characteristics of the scalded acid sulphate soils at nine sites along this coast were investigated. The investigated acid sulphate scalds are characterized by an extremely acidified topsoil layer (0–0.6 m) although they derive from the sediments of varying salinity and the metal sulphides contained in the soils have experienced different degrees of oxidation. Almost all of the investigated scalds occur in the areas that have a lower surface elevation than the surrounding areas. These hollows may act as sinks for acid sulphate materials and salts that are transported from the surrounding areas and the shallower watertables in such locations may enhance upward transport of acid and salt materials from the underlying oxidized sulphidic sediments. In general, the scalded acid sulphate soils have less organic matter and soluble phosphorus, and a greater salinity, soluble acidity, soluble Al, Mn and Zn concentrations, compared to the adjacent non‐scalded acid sulphate soils. These are most likely soil constraints for revegetation of the scalded lands and treatment will need to involve acid neutralization (e.g. application of lime) and addition of P fertilizers to reduce the soluble acidity, immobilize soluble Al, Mn and Zn, and increase P availability. The evidence also shows that the higher soluble Al concentration in the scalded soils, relative to the non‐scalded soils, is related to their lower organic matter content. Hence, rehabilitation of these scalded lands should involve the addition of organic matter to reduce soluble Al concentrations; it may also help reduce Mn and Zn toxicity, and salinity. Copyright © 2001 John Wiley & Sons, Ltd.