The present practice of basing payment for bacon pigs not merely on carcass weight, but also on carcass quality as expressed in the factory grading results, has led necessarily to an enlargement of outook on the part of the investigator in the domain of swine nutrition. The interest of the experimenter in the past has tended to be restricted to such questions as the influence of nutritional factors on the rate of live-weight increase and the efficiency of food conversion, the problem of how feeding may influence carcass quality and conformation not having received the attention its importance merited.While the questions of the rate of growth and the efficiency, in terms of meal consumption, with which such growth is achieved are still matters of primary economic importance, it is realized that much more attention must be devoted than heretofore to the study of carcass quality and conformation in relation to feeding. In present circumstances, a nutritional investigation can scarcely be considered complete unless a substantial part of the research is carried out in the bacon factory following the slaughter of the experimental animals.
An account has been given of an investigation into the seasonal changes in the productivity, botanical and chemical composition, and nutritive value of pasture grass, the work constituting the initial stage of a comprehensive study of the nutritive properties of different types of pasture. The pasture on which the work was carried out was situated on a light sandy soil of low water-retaining capacity; the pasturage was of medium quality.Grazing was imitated by the daily use of a motor-mowing machine, the system of cutting being such as to ensure the whole plot being cut over once per week. The season was divided into ten periods, each period corresponding with the duration of a digestion trial carried out on two wether sheep. The main feature of the weather conditions during the season was the extremely low rainfall during the period from early June to mid-July.The pasture plot results were compared with corresponding results obtained from contiguous plots which were allowed to grow for hay, and from which, after removal of hay, several successive aftermath cuts were taken. The main findings of the investigation are summarised below:Seasonal changes in the botanical composition of the herbage. Although precise and systematic botanical analyses of the herbage of the pasture were not carried out, yet careful surveys made at an early and a late date in the season, together with general observations made during the whole course of the experiment, enabled interesting conclusions to be drawn in respect of the seasonal activity and persistency of the different species of grasses in the sward. During the spring season,Bromus mollis, Lolium perenne, Poa annuaandPoa trivialisaccounted for almost 80 per cent, of the herbage.
The connection which has been shown to exist between the strength of wheat flour and the chemical individuality of the glutenine fraction of the wheat protein (Woodman, 1922) (1) led the writers to institute an enquiry into the manner in which the individual wheat proteins are developed and stored during the progress of the grain from the early stages after flowering to ripeness. The immediate object of the investigation was to secure information in regard to the stages at which the different proteins made their appearance in the grain and to determine at what point the character of the grain contents was such as to enable a tenacious gluten to be obtained by grinding up the kernels with successive quantities of dilute NaCl solution. It was also intended to follow the rate of alteration of the amounts of the several proteins during the growth of the grain and to attempt to elucidate as far as possible the relationships which exist between the simple and complex forms of nitrogen at the various stages.
The carrying out of digestion experiments with swine introduces difficulties of technique which are not encountered in similar work with sheep. The pig is apt to be restive under restraint and does not always take kindly to the wearing of harness. The designing of a suitable harness is not easy on account of the shape of the pig, and when confined in a metabolism cage, the animal frequently spends much of its time rubbing vigorously against the sides, thereby considerably disarranging the harness. Moreover, since the pig increases in size so rapidly, it is necessary that the fit of the harness be capable of adjustment within wide limits. A further difficulty is connected with the voracious appetite and destructiveness of the pig, so that if the experimental ration does not satisfy the hunger of the animal, the latter will often gnaw the wooden parts of the crate and will even devour its own faeces, if the degree of freedom of movement permits it to turn round. The quantitative feeding of a pig is a matter of difficulty, owing to the animal's eagerness and its habit of stepping into the food trough. Swine do not display such hardiness under confinement as do sheep, and it is therefore necessary to maintain an equable temperature in the metabolism room throughout the experiments.
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