Cattle temperaments in extensive beef herds in northern Queensland. 1. Factors affecting temperament

1988 ◽  
Vol 28 (6) ◽  
pp. 683 ◽  
Author(s):  
G Fordyce ◽  
RM Dodt ◽  
JR Wythes
Keyword(s):  
Growth Rate ◽  
High Growth ◽  
High Growth Rate ◽  
Factors Affecting ◽  
Pregnancy Status ◽  
Beef Herds ◽  
Selection For

The temperaments of 170 bullocks and 240 cows from 2 commercial properties in northern Queensland were scored by rating their behaviours, especially movement, while they were handled in a crush and pound. High scores indicate poor temperaments. Brahman cross cattle had higher temperament scores than did Shorthorns (P< 0.05). The heaviest cattle tended to have the lowest scores, suggesting that selection for high growth rate may not result in poorer temperament. Horned cattle tended to have lower temperament scores than hornless cattle (P> 0.05), though it is suggested that any advantage to horned cattle may be outweighed by the production and husbandry advantages of the latter. There was no relationship between temperament scores and age, fatness and, in cows, pregnancy status.

The biological efficiency of meat production in sheep

1970 ◽  
Vol 12 (3) ◽  
pp. 393-401 ◽  
Author(s):  
R. V. Large
Keyword(s):  
Growth Rate ◽  
Litter Size ◽  
High Growth ◽  
High Growth Rate ◽  
Biological Efficiency ◽  
Meat Production ◽  
Final Size ◽  
Artificial Rearing ◽  
Factors Affecting ◽  
Digestible Organic Matter

SUMMARYThe biological efficiency of meat production (E) is defined as the weight of carcass produced per 100 units of digestible organic matter (DOM) consumed. The factors affecting this relationship, for ewes and lambs, are discussed and the results of experiments are used to demonstrate the effect of number of lambs per year and size of ewe on the value of E. Calculations are made to show the effect on E of other factors such as the growth rate of the lambs and the weight at which the lambs are slaughtered. The general conclusions are that the highest values for E will be obtained from small breeds of ewes producing large litters and crossed with a large breed of ram, leading to a high growth rate and final size in the lamb. A relatively small increase in litter size in the small breeds of ewe (i.e. from one to two lambs) may result in a level of efficiency as high as that achieved by a larger breed with a large litter size (i.e. three to four lambs) without having to resort to techniques such as the artificial rearing of lambs.

Spontaneous variability of single isolates of Phytophthora infestans. II. Pathogenic variation

1970 ◽  
Vol 48 (5) ◽  
pp. 897-905 ◽  
Author(s):  
C. E. Caten
Keyword(s):  
Growth Rate ◽  
Generation Time ◽  
High Growth ◽  
High Growth Rate ◽  
R Gene ◽  
Physiologic Race ◽  
Pathogenic Variation ◽  
Resistant Varieties ◽  
Selection For ◽  
Physiologic Races

The variation in two aspects of pathogenicity, aggressiveness and virulence (physiologic race), among single zoospore cultures from three wild isolates has been examined. Two components of aggressiveness were measured, rate of growth on tubers and generation time on detached leaflets. Virulence was assessed from the pattern of compatible and incompatible reactions to members of the R gene differential series. Extensive variation in aggressiveness was detected in samples of zoospore cultures from all three isolates. The level of aggressiveness ranged from a high, equivalent to that of the parental wild isolates, to a complete lack of pathogenicity; as much as 45% was of the latter type. No instance of a change in virulence was found among 104 cultures tested.The significance of the observed pathogenic variation is discussed. It is concluded that zoospore variation is not important as a source of new physiologic races or strains adapted to particular, horizontally resistant varieties. Comparison of populations of zoospore cultures with samples of wild isolates suggests that directional selection for high growth rate and high and rapid sporulation operates in nature. The correlations between a number of cultural and pathogenic characters are examined, and an association between abundant sporulation in culture and high aggressiveness demonstrated.

scholarly journals Failure of growth regulation of the lens epithelium in strains of fast-growing chicks

1975 ◽  
Vol 25 (1) ◽  
pp. 79-82 ◽  
Author(s):  
R. M. Clayton
Keyword(s):  
Growth Rate ◽  
Growth Regulation ◽  
Genetic Selection ◽  
High Growth ◽  
High Growth Rate ◽  
Lens Epithelium ◽  
Normal Process ◽  
Fast Growing ◽  
Lens Fibre ◽  
Selection For

SUMMARYTwo strains of poultry selected for high growth-rate were found to have an anomalous lens morphology indicating a failure of the normal process of growth regulation. The implications for lens fibre differentiation are discussed, as are the implications for genetic selection for growth-rate.

Exploring SiC Growth Limitation of Vapor-Liquid-Solid Mechanism when Using Two Different Carbon Precursors

2013 ◽  
Vol 740-742 ◽  
pp. 323-326
Author(s):  
Kassem Alassaad ◽  
François Cauwet ◽  
Davy Carole ◽  
Véronique Soulière ◽  
Gabriel Ferro
Keyword(s):  
Growth Rate ◽  
High Growth ◽  
High Growth Rate ◽  
Carbon Precursor ◽  
Growth Limitation ◽  
Vapor Liquid Solid ◽  
Partial Pressures ◽  
Vapor Liquid Solid Mechanism ◽  
Vls Growth ◽  
Vapor Liquid

Abstract. In this paper, conditions for obtaining high growth rate during epitaxial growth of SiC by vapor-liquid-solid mechanism are investigated. The alloys studied were Ge-Si, Al-Si and Al-Ge-Si with various compositions. Temperature was varied between 1100 and 1300°C and the carbon precursor was either propane or methane. The variation of layers thickness was studied at low and high precursor partial pressure. It was found that growth rates obtained with both methane and propane are rather similar at low precursor partial pressures. However, when using Ge based melts, the use of high propane flux leads to the formation of a SiC crust on top of the liquid, which limits the growth by VLS. But when methane is used, even at extremely high flux (up to 100 sccm), no crust could be detected on top of the liquid while the deposit thickness was still rather small (between 1.12 μm and 1.30 μm). When using Al-Si alloys, no crust was also observed under 100 sccm methane but the thickness was as high as 11.5 µm after 30 min growth. It is proposed that the upper limitation of VLS growth rate depends mainly on C solubility of the liquid phase.

Very High Growth Rate of 4H-SiC Using MTS as Chloride-Based Precursor

2008 ◽  
Vol 600-603 ◽  
pp. 115-118 ◽  
Author(s):  
Henrik Pedersen ◽  
Stefano Leone ◽  
Anne Henry ◽  
Franziska Christine Beyer ◽  
Vanya Darakchieva ◽  
...  
Keyword(s):  
Growth Rate ◽  
Linear Dependence ◽  
Growth Rates ◽  
Molar Fraction ◽  
High Growth ◽  
High Growth Rate ◽  
Epitaxial Layers ◽  
Single Precursor ◽  
Very High

The chlorinated precursor methyltrichlorosilane (MTS), CH3SiCl3, has been used to grow epitaxial layers of 4H-SiC in a hot wall CVD reactor, with growth rates as high as 170 µm/h at 1600°C. Since MTS contains both silicon and carbon, with the C/Si ratio 1, MTS was used both as single precursor and mixed with silane or ethylene to study the effect of the C/Si and Cl/Si ratios on growth rate and doping of the epitaxial layers. When using only MTS as precursor, the growth rate showed a linear dependence on the MTS molar fraction in the reactor up to about 100 µm/h. The growth rate dropped for C/Si < 1 but was constant for C/Si > 1. Further, the growth rate decreased with lower Cl/Si ratio.

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