Cattle maintenance

E. coli 0157 H7 in cattle. In this regard, cattle shedding E. coli 0157 H7 provide the "fuel for the maintenance of this pathogen in the environment and for the infection or reinfection of additional animals. Thus, feces, manure, and soils in the production environment are a significant source of transmission of this organism. 

E. coli 0157 H7 was shown to persist in feedlot surface material, and also to multiply in feedlot soils of permissible moisture and manure content (Berry and Miller, 2005). The importance of environmental persistence in the maintenance of E. coli 0157 H7 in cattle production is further suggested by several studies that have reported that most isolates on a farm or feedlot are of one to a few genetic subt) es of this organism, which may predominate for months or years (Gannon et ah, 2002 Lahti et ah, 2003 Lejeune et ah, 2004 Shere et ah, 1998). In their longitudinal study of beef cattle at a commercial feedlot, Lejeune et ah (2004) found that most... 

These observafions make it interesting to speculate that greater persistence at cooler temperatures may be involved in the maintenance of fhis organism in fhe production environment during cooler winter weather when the rate of shedding by cattle t37pically is low. 

The most important manifestation of hyperfluoric status is dental and skeletal fluorosis. In regions of volcanic activity, and in some arid zones and areas where phosphorites and apatites are mined and processed, agricultural animals and population often suffer from endemic and civilization-related fluorosis that mostly affects the teeth and skeleton. There arises the problem of reproduction and maintenance of dairy cattle (Ermakov etal. 1998, Ermakov 2001). In toxic quantities, fluorides impair the metabolism of calcium and synthesis of bone collagen by stimulating bone accretion, and speed up bone resorption and total calcium turnover in the body (Susheela and Mukher-jee 1981). 

Cattle and sheep at low planes of nutrition Calves, beef cattle, sheep and dairy cows (up to twice the maintenance level of feeding)... 

As mentioned above, the translation of requirements into allowances that are used in feeding practice often involves the addition of safety margins. The justification for such safety margin is illustrated by the following example. Suppose that in 500 kg cattle the NE requirement for maintenance varies between individuals from 30 MJ/day to 36 MJ/day, with a mean value of 33 MJ/day. Although some of this variation may reflect inaccuracies in the methods of measurement used, much of it undoubtedly reflects real... 

The animals exemplified in Table 14.1 are all highly productive, but less productive animals use proportionately more of their energy intake for maintenance. It may be calculated, for example, that, on average, cattle in Africa use about 85 per cent of their energy intake for maintenance. 

Energy requirements for maintenance can be calculated from various feeding standards. Although it is not possible to include all the standards, requirements calculated using some of the most widely known standards are presented here. The energy requirements for maintenance of cattle published by AFRC (1993) are based on fasting metabolism (F, MJ/day) and can be predicted as follows ... 

In contrast to AERC (1993), where maintenance requirements are derived from calorimetric methods, the maintenance requirements of beef cattle published by NRC (2000) are derived using the comparative slaughter technique. This has the advantage of allowing experiments to be conducted under conditions more similar to those encountered in practice, and the effects of activity are implicitly incorporated. The NEjn requirement of beef cattle can be predicted from empty body weight (EBW) as follows ... 

Maintenance requirements are then adjusted for the effects of breed and sex, with the requirements of Bos indicus breeds being reduced by 10 per cent and the requirement of dairy breeds being increased by 20 per cent. The adjustment for effects of sex is similar to that made by AFRC (1993). Further refinements are also included for the effects of climatic factors and previous nutritional status. The NEn, requirements of dairy cattle published by NRC (2001) are derived from calorimetric studies and are predicted as follows ... 

The protein requirements for maintenance adopted by CSIRO (2007) are based on ARC (1980), but they specify separate estimates for EUP and MFP and recognise that MFP varies directly with level of feeding. For B. taurus breeds of cattle, EUP is predicted as follows ... 

An analysis of studies where the digestibility was determined in both sheep at maintenance and cattle fed at up to 4.8 maintenance revealed no clear effect of level of feeding on the ME content of the diet, nor between species.AVhilst FiM does correct for level of feeding, a fixed increase in ME requirements of 0.02 ME is made, irrespective of feeding level. This is illustrated in Box 16.3. 

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