USE OF PASTURES AND PASTURE-EQUIVALENTS IN PIG-KEEPING.

New Zealand Journal of Agriculture, Volume 53, Issue 4, 20 October 1936, Page 204

USE OF PASTURES AND PASTURE-EQUIVALENTS IN PIG-KEEPING.

RECOMMENDATIONS OF THE MANAWATU-OROUA PIG RECORDING AND DEVELOPMENT CLUB.

R. P. Connell,

Fields Division, Department of Agriculture, Palmerston North.

There are great variations in the degree of success with which pastures are being utilized in' pig-keeping. These variations are due primarily to differences in the extent to which pasture utilization by pigs is based upon the following important facts. The- digestive organs and processes of pigs differ materially from those of other farm animals fed on pastures — sheep and cattle. From the digestive viewpoint cattle and sheep are much better fitted naturally to utilize much more bulky foods of low digestibility than are pigs. ■ln the first place, cattle and sheep, but not pigs, are. ruminating animals. In ruminating animals the food after being swallowed for the first time, does not ordinarily reach the true digestive stomach until it has been first brought back to the mouth, where it undergoes a very thorough mastication or “ chewing of the cud ” which reduces it to a finely divided condition that facilitates the action of digestive juices. This in its turn enables the ruminants to digest more effectively than nonruminants feeds of low digestibility, such as woody or stemmy crops— pastures of rank or mature growth. In the second place, the alimentary canal in which digestion takes place is relatively much greater in cattle and sheep than it is in pigs. The volumes of the alimentary canal in different animals comi r 2 _i _ ' • 1 • - ■

puted from data given by Colin are —

Volume of Alimentary Canal

per 100 lb. of Live-weight. (In Pints.) Cattle .. .. .. 50 to 60 Sheep.. .. ' ... .. 50 to 60 Pig .. •• . .. .. 16 to 20

These figures, which obviously vary, depending on the size and condition of the animal, are in general agreement with those of other authorities.

The volume of the alimentary canal is of basic importance in feeding. Its function has • been likened rather aptly to ■ that of factory-space. Just as a .large factory can handle more material than a small factory, so, in a similar way, an animal with an alimentary canal of large volume in comparison with its weight can utilize bulky supplies of feed better than can an animal having an alimentary canal of comparatively small volume. In this case feed .is the raw material out of which flesh. or milk 'is manufactured, and from the previous data it is clear that the cow and the sheep have spacious alimentary canals in comparison with the pig. There are great differences, vital in .pig-feeding, between the characteristics and feeding-values of pastures of leafy relatively short young growth'. and of ones of stemmy mature or rank growth: These differences are intensified when the latter pastures are characterized by the absence, or the markedly scant supply, of clovers, which are specially rich in proteins and mineral matter. The comparative feeding-values of leafy growth of pastures and of stemmy growth may be gauged from the following facts : (i) The dry matter of samples of leafy pasture contains approximately twice as much phosphate and lime as the dry matter from corresponding, herbage at the hay stage. ' (2) The dry matter of leafy pasturage contains approximately two and a half times as much protein as occurs, at the hay stage. (3) • About 80 per cent, of the dry matter of leafy pasturage is digestible, whereas only from 40 per cent, to 60 per cent, of the dry matter of stemmy growth is digestible. The true significance of’ these three facts ' lies in the further fact that the rations of animals capable of a high rate of production, such as pigs, are apt to fall short of the full requirements in. respect to their mineral and protein contents and their digestibility. From this it follows that any system of pasture utilization which brings about. rank herbage or which lessens the clover content of pastures is in those respects unsuitable in pig husbandry. •• There are important differences between (a) . leafy growth of pastures, roots, and green crops and (b) skim-milk, whey, cereal grains and meals, and meal and fish meals. The position is indicated by the following table :

Yield, of Nutritive Material (expressed as Pounds of Starch Equivalent) from z loolb. of Dry .Matter.

Lb. Skim-milk .. . . ■ . . .. 99 Whey . . . . . . . . • • 93 Maize . . .. . . . . .. .. 96 Peas . . 1 .. .. ' . . . . .. 90 Barley . . .. , . .. ... 87 Meat-meal (containing a good deal of fat) .. .. 137 Leafy grass .. . . .. . . - 70 to 80 Carrots ... .. .. .. .. 70 Swedes .. ' .. .. .. .. 66 .Chou moellier .. .. .. . . .. 66 Coarse grass .. .. , .. .. •40to 50 Hay .. . . .. ’ .. ' ... 30 to 45 .Straws .. .. .. ■ ' . . 15 to 25

This table shows that feeds can be grouped into- three distinct classes—(i) Poorly digestible or : bulky; (ii) readily digestible or non-bulky. Cereals, meals, and skim-milk belong chiefly to the latter, in which skim-milk is outstanding; while hay, straw, and coarse grass belong to the former. To obtain any given amount of nutriment the digestive apparatus of the animal has to deal with much more feed material (irrespective of its water content) in the case of the former than that of the latter, which therefore are more suited in general to the needs of animals with relatively small volume of alimentary canal, (iii) Leafy pasture-growth, root crops, and green fodders before ■ they ■ become woody are intermediate in character: in practice they serve as readily digestible non-bulky feeds when not fed in excess, or as poorly digestible’ bulky feeds when fed in large 'amounts. • ' Because of the limited capacity of the alimentary canal of the pig the difference between bulky and non-bulky feeds is of prime importance. Hence it is well to bear in mind that a feed which from the storage viewpoint is bulky is not necessarily bulky also from the nutritive viewpoint. Bulkiness in respect to nutrition is governed largely by the character of the dry matter : if a substantial amount. of the dry matter is not readily digestible; as when the. feed is woody or of high fibre content, then for nutritive purposes the feed is bulky, whereas if the dry matter is of. high digestibility, as when its fibre content is low, then the feed is nonbulky. Hence, for practical purposes skim-milk, from which fibre is absent, is non-bulky, whereas hay or silage, with a fibre content of .25 per cent, to 35 per cent, of its dry matter, is bulky, and pasturegrowth with a fibre content of 10 per cent, to 20 per cent, of its dry matter is of intermediate type. The bulkiness of the feed itself as distinct from its dry matter is of some moment, but the dominant consideration is the character of the dry matter as determined largely by its fibre content..

There is a close and inescapable connection between economy in feed-consumption and rapidity of growth. This may be illustrated by considering the feed requirements of a pig of 200 lb. live-weight. Such a pig requires for mere maintenance the equivalent of 3-6 lb. of meal daily and an additional 2 lb. of meal or its equivalent for each 1 lb. increase in live-weight. Hence, if such a pig is growing at the rate of 1 lb. daily a total of 5-6 lb. of meal or its equivalent is required to produce 1 lb. increase in live-weight, but if the pig is growing at the rate of only | lb. daily then 9-2 lb. of meal is required to obtain 1 lb. increase in live-weight. . This means that in respect to production of flesh the effectiveness of the feed used at the slower rate of growth is only 60 per cent, of that of the feed consumed at the quicker rate of growth. Keeping this in mind, let us return to the use of bulky/ and non-bulky feeds. In growing animals the maintenance requirement is met first, only the balance over and above this requirement being ’ available for production. If the pig, with its limited “ factory ” capacity, is fed on bulky feeds the nutriment available will be only little, if at ■ all, in excess of the maintenance requirement : if the pig is given non-bulky feeds comparatively . large amounts of nutriment will be available for

production. Hence, if it is desired to obtain growth at the maximum rate then easily digestible non-bulky feeds should be fed. Such easily digestible non-bulky feeds are often called “ concentrates,” the most important of which in New Zealand dairying are skim-milk (a diluted concentrate), cereals, and peas. It follows from the facts just considered that in the interests of feedeconomy concentrates such as skim-milk should be used as exclusively as possible in the production of flesh, and to enable this to be done less concentrated feeds, such as pasture-growth, root crops, and green forage crops, should be used mainlyand as much as possible to replace concentrates maintenance. The more such crops can be used for maintenance the greater is the amount of -produced concentrates available for flesh-production with a minimum of feed-consumption. This is the key to the judicious use of pastures and pasture-equivalents in pig-keeping as a subsidiary venture to dairying. In dairying the production of concentrates in the form of dairy by-products is distinctly and definitely limited ; the provision of other concentrates, such as the grains of barley, maize, and peas, either by farm-production or by purchase, is costly in comparison with the provision of less concentrated feeds . such as pasture-growth, root crops, and green ■crops. Access to pastures or crops of similar nature is frequently valuable because of the exercise it provides and because of its influence upon the health of animals. This results from the freer provision of vitamins and of sunshine. The pig, whether it be the sow with young. or the growing animal, normally is capable of high and efficient production. One aspect of this is reflected in the computation that for 100 lb. of digestible nutrients consumed — (a) The pig produces 25 lb. of. dressed carcass, equivalent to 15 lb. of edible dry meat ; (b) the sheep and steer yield less than 10 lb. of dressed carcass, equivalent to only from 2| lb. to 3J lb. of edible dry meat.' But from data already discussed it is clear that such economical conversion of feed into meat is compatible only with feeding which allows the maximum rate of growth to be attained. This in its turn is incompatible with the free use of somewhat coarse feeds of relatively poor digestibility or the general toleration of any substantial “ store ” period in the case of animals being prepared for slaughter. . The sow with young ranks with the rapidly growing pig in its high rate of production and in its need for a high standard of feeding. The position in respect to well-developed dry breeding-animals is somewhat different, rations slightly in excess of maintenance requirements normally being sufficient for these. Further, a “ store ” period in the case of animals being grown for slaughter is at times justified, when, for instance, the store ” period enables advantage to be taken later of a cheap concentrate as occurs when pigs are wintered as stores and finished off on dairy by-products in the spring, and when the alternative to the store period would be the use of concentrates, expensive in comparison with dairy by-products. In such cases the . winter “ store ” period—. i.e., the period of relatively slow growth — the use mainly of farm-grown crops, which can be provided at a comparatively low cost.

Summary of ’ Basic Principles of Successful Utilization of Pastures by Pigs. ' To sum up, the successful utilization of pastures and kindred crops in the production of pig-meat as a subsidiary to dairying are based largely upon the following considerations : (1) The digestive organs of the pig are unfitted to utilize coarse bulky feeds effectively. (2) Coarse swards containing but scant amounts of clovers are substantially inferior to the short leafy growth of wellbalanced mixtures. of grass and clover in respect to their ‘digestibility and their content of flesh-forming substances and of mineral matter. (3) To exploit the capacity of the pig for high production and rapid growth, highly digestible rations rich in minerals and flesh-forming substances must be provided as far as is compatible with costs and returns. (4) Economy in feed-consumption is governed by rapidity of growth. , (5) While highly concentrated feeds such ’as skim-milk and cereals are desirable for rapid growth, less concentrated feeds serve well for maintenance., (6) The less concentrated feeds as a rule are cheaper or more easily obtainable than the highly concentrated ones, the use of which should be confined as much as practicable to the pigs of highest production pigs for slaughter and sows with young. • ' . (7) Irrespective of direct feed-economy, access to pastures and , other crops of similar nutritive value is useful in respect to health and to exercise, which may affect carcass quality. Practical Application of the Principles. The application of these concepts in practice may be summarized as follows : (1) Pasture-utilization should be based upon extensive rather than upon intensive methods of grazing. (2) Considerable use . should be made of pastures for — (a) Dry sows : . ‘ (&) Suckling sows with litters : (c) Not as a rule for pigs definitely being fattened, for which, however, access to pastures at regular intervals should be . provided. Especially, however, should young pigs have access to pastures and outdoor conditions for some time immediately after weaning : (d) Store pigs only if fluctuations in the feed-supply make this advisable ; generally a store stage is undesirable. (3) It is desirable to provide pasture-equivalents for use during periods of pasture-shortage; crops which yield suitable equivalents, including lucerne, subterranean clover, broad red clover, Montgomery red clover, green cereals, and chou moellier and roots. (4) Where practicable it is desirable to grow cereal crops or peas for grain, such crops because of their less bulk being valuable in conjunction with the pasture-equivalents.

Extensive versus Intensive Methods of Grazing

. Extensive methods of grazing may be practised by giving the pigs range over pastures of several acres the feed from which is consumed mainly by dairy cows. It contrasts with the intensive method of grazing, in which the pigs are confined to relatively small areas of grassland : one of the layouts which has been recommended commonly for this purpose provides for the subdivision of an area of 2 acres into ten small paddocks to which access is given by a central race and beyond which the pigs are not to be allowed to graze. It has been demonstrated that the intensive system, involving the use of only small • paddocks, when operated with' suitable equipment facilitates the convenient and systematic feeding of pigs ; further, because of its open-air character and the grazing that it permits, it is definitely superior to a system under which pigs have little or no access to grassland. On the other hand, it has been found in practice to have certain substantial disadvantages apart from its cost, which is considerable. In the first place over a wide range of conditions, in winter and early spring, when usually leafy feed is particularly needed, the small paddocks are “ poached ” or “ pugged ” or productive of comparatively little feed. In the second place, eventually, and indeed fairly soon, the feed in the small paddocks deteriorates greatly, becoming less wholesome and less attractive. This is due to unavoidable changes in the composition of the swards of the small paddocks, changes which necessarily arise from the enrichment of the soil due to the excreta of the pigs. The changes normally consist of clovers being suppressed and grasses becoming dominant and coarse. It becomes difficult, if not impracticable, to keep the resultant herbage short and leafy, and even if it is kept fairly short and leafy it may be expected to be relatively poor in mineral matter, which is believed to be of considerable moment in the nutrition of pigs. It would be much better to avoid, as far as possible, the undesirable change in the composition of pastures by having the animal manure from the pigs distributed as evenly as possible over, say, 12 acres to 20 acres instead of 2 acres —a result which is at least partially secured under extensive methods of grazing. Distributed over the larger area the manure leads to improvement, whereas concentrated on the smaller area it leads to deterioration of pasture. Grazing by the extensive method is sometimes far from successful. To be successful the grazing must be arranged in such a way that the pigs receive not only highly nutritious feed —fresh, leafy, and satisfactorily rich in clover-but also ample amounts of such feed. In the winter especially pigs are often grazing on bare pastures. Poor results may be expected from pigs so grazing unless suitable supplementary feeding is carried out, just as the results are poor from cows grazing on bare pastures without suitable supplementary feeding.

Because of the highly profitable returns obtainable from wellfed pigs, and because good feeding of the pig calls for the provision of feeds of relatively high nutritive value and digestibility, there is no justification for management which gives the pig second

place to the dairy cow as is sometimes done by making pigs “followers” to cows on pastures. When this practice is adopted the cows naturally consume the choice leafy herbage, leaving the comparatively inferior stemmy herbage for the pigs, which are less fitted physiologically to use such herbage effectively than are dairy cows. Against grazing by pigs on wide range by the extensive method it has been objected that damage to the pastures results from the rooting habit of pigs. It has been shown, that danger of such damage can be removed by suitable “ ringing ” of the pigs. Another objection often raised to extensive grazing by pigs is that ordinary fencing is insufficient to keep pigs from roaming widely . and even on to neighbouring farms. Experience shows that as a rule pigs do not pass through a seven-wire fence reasonably well made and maintained, but that fences in bad repair and poor feeding both beget wandering habits, which are not eradicated readily and which may lead to pigs going through even good fences. Further, areas of special crops usually can be secured without much effort or cost. A further objection raised to extensive grazing is that the pigs would be subject to tubercular infection from herbage contaminated by infected cows. Veterinary opinion is that generally any danger in this connection is small, that it is at least offset by the greater vitality with greater general resistance to disease which results from the more healthy conditions provided by extensive grazing, and hence that the expectation of disease in pigs on wide range is less than in confined pigs. A possible exception to this arises in the case of pigs grazing after cows suffering from tuberculosis of a type which leads to discharge of the tubercle on the herbage. While as much extensive grazing as possible is advocated, it is not to be deduced from this that no small paddocks are desirable. As is indicated later, the use of small paddocks for particular purposes and particular circumstances is recommended. But because of the cost of providing small paddocks suitably equipped for the convenient watering and feeding of stock, and also because of the drawbacks to the small paddocks relative to grazing which have already been considered, the aim throughout should be to reduce the number of small paddocks as much as is possible having regard mainly to the beneficial influence a small amount of green feed, exercise, and open-air life may have upon the well-being of the pig. Dry Sows on Pastures. Great success has attended the grazing of sows between the weaning of one litter almost up to the farrowing of the following litter. When the pastures used for this purpose have been ones of high quality yielding leafy herbage sows have lived largely, if not wholly, on the pastures alone for long periods, and the subsequent results have been good. The mature sow can with safety live more completely upon pasture-growth than can the young developing sow, the requirements of which are greater to meet not only the needs of maintenance and pregnancy which are common to both mature and developing sows, but also those of growth. The feeding of sows on pastures in this manner is of great practical moment

because it increases the proportion of dairy by-products available as a concentrate or non-bulky feed for use in rapid flesh-production by pigs for slaughter. That quite a substantial amount of additional cheap concentrate may thereby be made available for rapid fleshproduction may be gauged from the fact that the maintenance requirement of two pigs of 250 lb. live-weight has been estimated- to be approximately equal to the maintenance requirement of a cow of 800 lb. live-weight. Probably the feeding of breeding-sows extensively upon pastures of poor or badly balanced botanical composition or of stemmy overmature growth would provide a deficient diet and result in poor litters. On the other hand, observation shows, that, if no other factors intervene, good litters may be expected from sows grazing on pastures providing abundance of high-quality leafy herbage. Sows with Litters on Pastures. The essential difference between the grazing management of dry sows and that of sows with litters arises from the desirability of having full control of the litter. One way of securing this is the provision of a small paddock of grass to which there is access from the stationary, wing-quarters. This small paddock probably is of more value as an open-air accommodation area than as a grazingarea from which nutriment is obtained. What is a suitable size for such a paddock varies with the nature of the —a smaller paddock suffices on well-drained soil. Paddocks ranging in size from about | acre to J acre are proving serviceable according to the conditions. Such small “ accommodation ” paddocks should have direct access to larger paddocks for grazing by the extensive method when the litter is old enough to be allowed wide — i.e., after it is about four weeks old. Up to' weaning, the sow with litter is fed and housed at the owing-house. Store Pigs on Pastures. The normal procedure, having due regard to feed-supplies and feed-costs, should be to eliminate a store stage by providing from weaning to slaughter stage rations which meet not only maintenance requirements, but also full production' requirements. Such rations provide the essential basis for the rapid growth and consequent economy of feed which has already been discussed. However, as the result of seasonal fluctuations in the supply of cheap concentrates — dairy by-products —it may become possible to supply such rations only in the form of farm-grown or purchased concentrates, and this at a cost which is not economic or maybe not so economically attractive as would be an alternative course. This alternative course consists in having the growing pigs pass through a store stage, during which they are fed largely on pastures or pastureequivalents which provide a relatively cheap supply of feed. The wintering of store pigs which later utilize effectively the supplies of dairy by-products in the spring often is a useful application of this. For this purpose, when the supply of feed directly available

from pastures is inadequate, it often may be supplemented suitably by the use of one or more of several farm-grown crops, including mangels, carrots, swedes, . pumpkins, chou moellier, temporary pastures, green cereals, and subterranean clover; and the use of limited amounts of concentrates e.g., grains of cereals, including maize, peas, meat-meal, and meals of similar nature —to supplement such crops is usually sound economically. Similarly, in the latter part of the summer, if the milk-production falls off at an abnormally rapid rate because of exceptionally dry conditions a store stage for growing pigs may become advisable, and then areas of lucerne and pastures rich in red clover are fitted to provide valuable yet cheap grazing. The best results from the grazing of store pigs are normally obtained from adoption of the extensive method of grazing, and the pigs may be accommodated in special inexpensive housing. The Use of Grass for Pigs being fattened. Recent investigations carried out at Massey Agricultural College and at Ruakura Farm of Instruction give results which are in agreement and which also are in general agreement with the results of similar overseas investigations. Further, these results confirm the experience of many successful farmers in indicating that little, if anything, is to be gained in regard to direct economy of feed from the grazing of pigs being prepared for slaughter. Hence the use of fattening-pens is advocated. It is considered advisable by some, however, that, in general, pigs being prepared for slaughter should not be confined continuously throughout the after-weaning period to the fattening-pens. Because of this each fattening-pen should have a companion small paddock of grass to which the pigs should be given access for relatively short periods at regular intervals. Farmers who adopt this practice consider that it fosters good health, and that in the case of pigs which tend to develop too much back-fat the practice minimizes or corrects this tendency. Some experimental work carried out in New Zealand supports this view.

The General Objective summarized

Leafy pasture-growth, especially when not poor in clover, being intermediate in character between non-bulky and bulky classes of feeds, and being suitable for use as a non-bulky feed when not consumed in excess by pigs, may be made a very important and inexpensive part of the rations used in pig-keeping. On the other hand, coarse stemmy pasture-growth, being a bulky feed, has little if any value as part of the rations of pigs. Because of the fundamental difference between leafy and stemmy growth the basic purpose of pastureutilization by pigs should be the provision of leafy growth. This .means appropriate pasture-control, which in the case of grazing by the extensive method can be obtained readily by using cattle as the agents of control. In the case of the small paddocks prescribed for the use of sows with young litters and of fattening pigs it is difficult, if not impossible, to maintain suitable control of the pasture-growth by the grazing of pigs only, and it is usually advisable to resort to the mower and to other grazing-stock such as sheep and store cattle as aids to the control of the growth.