CARCASS-QUALITY IN BACON PIGS.

New Zealand Journal of Agriculture, Volume 54, Issue 3, 20 March 1937, Page 147

CARCASS-QUALITY IN BACON PIGS.

C. P. McMeekan,

Massey Agricultural College, Palmerston North.

PART I.—NEW ZEALAND BACON PIGS IN RELATION TO UNITED KINGDOM MARKET REQUIREMENTS.

The export from New Zealand of frozen pig carcasses suitable for conversion into bacon is a comparatively recent development of the New Zealand pig-industry. Recognizing that types of pigs and feeding practices common in New Zealand are radically different from those in European countries supplying the United Kingdom market, the Manawatu-Oroua Pig Development and Recording Club designed the experiments detailed below to determine (a) the suitability for the United Kingdom market of the various types of bacon pigs in New Zealand, fattened on different dairy by-products, and (b) whether the supplementing of factory buttermilk with meals improves the quality of carcasses and/or the financial returns. In designing the experiments the club wished to ascertain in particular whether the Tam worth, Berkshire, and Tam worth-Berkshire crosses of varying degree so peculiar to New Zealand and Australia produce carcasses markedly different from the white breeds of European countries, and whether the feeding of fattening pigs almost exclusively on dairy by-products is fundamentally sound in respect to both the financial returns and the quality of the product. The quantitative and economic results have been reported in another paper (9). The present communication is concerned only with the carcass-quality of the pigs. This is divided into two parts, the first being a study of the quality of carcasses produced from pigs of various breeds and crosses, reared and fattened on different farms, and the second dealing with the influence on carcass-quality of supplementing buttermilk fed to fattening pigs with concentrate meals at varying rates and over varying growth-stages. Source of Pigs and Method of Examination. Arrangements were made by the club’s recording officer (Mr. W. J. Croucher, who also carried out the inspection and measurement of the pigs and the arranging of the trials) for a number of farmers to market selected lots of pigs representative of the average quality of New Zealand baconers, through one organization, which arranged for the slaughter, freezing, export, and disposal of the carcasses. In addition, pigs were available from feeding trials conducted at the farm of the Cheltenham Dairy Co., Ltd., and these were marketed through the same channel. Table I gives details of the number of pigs slaughtered and exported.

The pigs were slaughtered at the Kiwi Bacon Factory, Longburn, where as complete an examination as possible without cutting of the carcass was made. The carcasses were suitably identified,, frozen, and shipped to London as the numbers accumulated. Here they were examined by the New Zealand Pig-carcass Evaluation Committee, established for the purpose, and composed of recognized authorities on carcass-quality(i). In each year the carcasses were examined at the same time. The order of reference under which the committee worked was as follows : “ The general object of the consignments is to obtain critical and candid expert United Kingdom opinion upon all carcasses as to their suitability in respect of quality and weight for the United Kingdom bacon trade, the reports to indicate any specific weaknesses or defects to which the attention of the New Zealand producer might profitably be directed.” The system of examination employed was very comprehensive and thorough, and was as described by Davidson, Hammond, Swain,, and Wright(r). Complete data for each carcass on a basis of this, method were supplied by the committee, together with individual photographs of loin-cuts. The committee also presented a statement, covering the general conclusions reached. It is convenient to note at this stage a slight variation in the method of examination in the evaluation of “ proportion of fat ” and “ streak.” In the 1935 shipment the former was measured at the point of eye,” while in the 1936 lots, at a point “i| in. in from the middle line ” on the loin-cut. The streak was evaluated by measurement on the loin-cut in 1935 and by eye assessment, and standard photographs in 1936(1). Otherwise the methods used were identical for every carcass. Summary of Evaluation Committee’s Report. The following extract from their reports summarizes the views of the committee : “ (a) Conclusions. — Viewing the shipments from a broad quality-angle, the following generalities may be made “ (1) The outstanding defect was a general deficiency in' length, which is one of the most desirable characteristics in pigs destined for the Wiltshirebacon trade. Broadly, these pigs averaged 738 mm., for length of loin as against 800-850 mm. for Danish pigs of comparable weights. “ (2) The consignments as a whole were good in relation to thickness of streak, eye of meat (indicating presence of ample lean meat), fineness of shoulders, and the hams were of good conformation. “ (3) The thickness of back-fat was, on the whole, fairly good. “ (4) It is emphasized that pigs below 126 lb. in weight are too light for the bacon trade. “ (6) General Policy.— The present position would appear to be that baconer pigs now being exported from New Zealand are the surplus pigs of the porker . trade fed on to bacon-weights. In other words, the present baconer pigs

appear to be porker-type pigs fed to bacon-weights and so are short in length in relation to weight. If the baconer pig from New Zealand is to be merely a by-product of the porker trade, we would advise marketing the present type of comparatively short pig at the lower bacon-weights — i.e., at weights below the present English standard minimum of 140 lb. Otherwise there will be a marked and undesirable disproportion between length and fatness. If taken on to heavier bacon-weights the extra weight will be mostly fat and would result in a pig unsuitable for the bacon trade. It should be emphasized, however, that this type of lowweight baconer pig has a somewhat limited market which could be easily saturated. On the other hand, if New Zealand is going to make the baconer pig a primary product with a view to competing with the Continental type of pig it is vitally necessary that a different type of pig having greater length and maturing at a rather heavier weight should be bred. The development of this policy should not impinge on or adversely affect the present porker production, which has now attained a high standard and is of considerable importance in that it has few competitors compared with the baconer trade in the United Kingdom market at the present time. “If it is thought desirable to introduce this new type of baconer it should be largely additional to the present pig trade and not as a substitute for it.” The above statement is illuminating in several directions and deserving of the serious consideration of producers, breeders, and ■others interested in the development of a profitable and extensive ■export bacon trade. The position calls for a more detailed presentation and examination of the data on which the observations have been based. Carcass-quality Results. Limitations of space preclude presentation of the detailed measurements and other data for the individual carcasses. The system of award of marks according to a definite scale on a measurement basis makes it possible, however, to obtain a reasonable picture of the average results, by expressing the actual marks received for the individual and total points as percentages of the possible awards in each case. This method overcomes the disadvantage of weight-disparities in making comparisons. It fails to allow for differences, in the relative importance of the different points, however. The fact that eye of loin, length, proportion of fat, and streak together account for 80 per cent, of the possible marks in carcass-quality as a whole (hams, shoulders, and leglength being of less importance) should be borne in mind in examining the figures. Comparisons between each farmer’s lot and between the different breeds and crosses are set out for quality .as a whole and for the individual characters in Table II (next page).

The average value of the carcass-quality, awards over all the pigs was approximately 60 per cent., a figure leaving much room for improvement. Individual farmer’s lots varied from 44 per cent, to 75 per cent, in carcass-efficiency. The most common and serious cause of failure to reach high standards was shortness in length of loin. This was responsible for an average value of approximately 40 per cent., and, in the. case of individual lots, for a variation of from 15 per cent, to 71 per cent. The figures bear out the contention of the committee, and point to the necessity for immediate attention to remedy this defect. Eye of meat gives a disappointing value and a fairly variable value of from 32 per cent, to 80 per cent. It seems evident that the outstanding merit of New Zealand pork carcasses in this important character(2, 3) is not a characteristic of many pigs of bacon-weights. The proportion of fat in the carcasses is more satisfactory, a reasonable average standard of approximately 75 per cent, of the optimum being obtained, despite the general tendency of short-type pigs to show a marked disproportion between length and fatness." Had a greater number of the pigs been carried to heavier weights it is conceivable that the situation might not have been so favourable, but more in keeping with the committee’s comments. . ■ The relatively good values obtained for streak are surprising in view of the frequent adverse comment from trade interests upon this qualitypoint. This apparent contradiction results from the fact that while the thickness of the streak in proportion to the weight of the carcass was excellent, the actual thickness was insufficient, due to the low average weight of the pigs. This emphasizes one of the disadvantages to the trade of weight baconers. While the proportions of such carcasses may approach the ideal, the actual measurements of a particular area, such as the belly region, may render the latter almost valueless. On the basis of this argument and the actual results obtained it is evident that much of the trade criticism of the bellies of New Zealand baconers should be overcome by marketing within the higher bacon-weight range. Hams, shoulders, and legs attained a good standard over the pigs as a whole, though individual lots show a low value for legs in some cases, due to excessive length of leg. Breed and Cross in relation to Carcass-quality. The average figures for the different crosses and breeds were remarkably close, showing a range of only from 60 per cent, to 63 per cent, for carcass-quality as a whole. This supports the view previously expressed(4) that there is little difference between New Zealand breeds and crosses as to gross efficiency. Between the various breeds and crosses characteristic differences are apparent, however, in respect to carcass-quality. These may be summed up as follows : (1) Tamworth-Berkshire crosses are very good in hams, shoulders, streak, and eye of loin, but are distinctly short. (2) Tamworth - Large- crosses are superior to all others in length of loin, are better than the first-mentioned cross in proportion of fat, but ’inferior to all crosses in eye of loin,, length of leg, and hams.

(3) Tamworth - Large-Black crosses are the shortest of all breeds and

crosses compared, and have excessive leg-length. Otherwise they are comparable with the Tam worth-Berkshire group. (4) Large-White - Berkshire crosses are good in proportion of fat, but. deficient in loin-length and eye of meat. They have not the leg weakness of the Tam worth - Large- cross. (5) Although the numbers of purebred animals are small, the average values attained are of ‘interest. Large Whites have the greatest length, being better than any cross in this character. They have inferior eye of loin awards, and low leg-values. Tam worths give good length and fat values, but inferior legs and hams. Large Blacks are short of loin and excessively . ■ leggy. . . . ' . It must be emphasized that these figures and comparisons, in view of the relatively small numbers of pigs involved, may not necessarily be representative of these breeds and crosses in New Zealand, and may rather be the picture of the average . quality of different strains. With this limitation the . data indicate that it is possible to obtain reasonably, good-quality carcasses from any of the existing breeds and crosses, though one may be, on the average, superior to another in respect to individual quality characters (Plate 1, next page). As distinct from these interbreed differences, wide variations in both carcass-quality as a whole and in individual quality-points are apparent within each breed and cross. This feature of the results is of particular significance since it points to the existence within. a breed of pigs of different “strains” of varying carcass-efficiency,’ Though it is conceivable that the variations referred to may be due in part to management and feeding, this is unlikely in view of the nature of the differences. The wide variation in carcass-efficiency of 30 per cent, within the Tamworth-Berkshire cross illustrates the point, differences in length of loin, length of leg, and proportion of fat, either singly or in combination, being responsible. Some farmers are seemingly provided with definitely superior classes of stock irrespective of breed. The position may be put another way : the differences within any one breed or cross, particularly in respect to length of loin, points to the existence of distinct “ types,” some of which are more suited to bacon-production than others. How far selection within these types will assist in the development of a higher standard in the national output is a matter of considerable moment. In this connection it is perhaps significant that within the Tamworth-Berkshire group most popular cross in New Zealand — no lot was capable of securing greater efficiency in length of loin than 54 per cent. Weight in Relation to Carcass-quality. •The emphasis placed upon weight of carcass as a factor in quality by the committee has led to an examination of the data available ’with the object of determining the relationship more closely than illustrated by the general statement. The contention that New Zealand, pigs are of a type which mature at lighter weights than the bacon-weights more in demand involves the concept that changes in the relative proportion

of bone, flesh, and fat occur as the pig grows, and that the’rate of development of such changes varies with the breed or “ type ” of pig.. Bone develops first, flesh next, and fat last. Some breeds and types "mature,” or have the desired proportions of bone, flesh, and fat, at lighter weights than others. This, on the one hand, makes some breeds, and types more suited to pork-production and others to bacon-produc-tion, and, on the other, sets an optimum slaughter-weight for any given breed or type. An increase in weight above the optimum will be mostly fat and the resultant carcass less suited to market requirements (3, 5,6). Changes in length of loin, proportion of fat, and thickness of eye of loin, with changes in weight, have been investigated.

The relative length measurements at 5 lb. ranges from 115 lb. to 160 lb. are compared with the "standard” lengths for weight taken from the committee’s published 'data(i). The deficiency in length relative to standard at each weight has been calculated, and the actual increase per 5 lb. increase in weight compared with the standard increase in length. . Since the “ standard ” lengths for .weight are based on the trade requirements for this character, and represent the ideal, the figures for the New Zealand carcasses measure, the deficiency of the baconers at the various weights. While length of loin has increased with increase in weight, the rate of increase has not been rapid enough, with the result that the deficiency below standard becomes progressively greater as weight of carcass increases. The effect is sufficient to penalize commercially the heavier carcasses. The data indicate fairly conclusively that the length weakness in the present type of New Zealand bacon carcass, if this sample be taken as representative, will be less apparent at light bacon-weights, the pigs being of the relatively early maturing type in respect of length of loin — i.e., comparable with pork-type pigs.

* Cold-dressed carcass-weight.

Eye of loin shows but little variation within the weight-ranges studied, its thickness tending to increase but slightly with weight-increase. This would lend support to the contention that flesh is an early developing part in the pig-carcass, the proportion as indicated by the ■eye measurement having reached nearly maximum development at the lower bacon-weights in these carcasses. That the increase is sufficient to conform with the desired standard increase is indicated by the relatively uniform percentage marks awarded. It is not likely that weight of carcass within the bacon-weight range is a material factor in influencing the eye measurement.

Proportion of fat, on the other hand, shows a.similar undesirable tendency to length, - an increase in the thickness at point of eye occurring with increase in weight, and the increase being greater than required if the “ standard ” thickness for weight be taken as a criterion. The position is clear from Fig. 2. The pigs tend to approach the ideal in proportion of fat more closely at lower weights than higher, but it is important to note that the effect is not nearly as great as in the case of. length and makes little material difference at weights up to 140 lb. and even up to 150 lb. This situation is significant in view of the fact that it is frequently necessary to market at least a proportion of bacon pigs at weights above 140 lb. in consequence of the seasonal nature of foodsupplies in New Zealand.

Farm Feeds in Relation to Carcass-quality.

The experiments have shown that the practice of fattening pigs in New Zealand on a ration entirely or almost entirely composed of dairy by-products is capable of producing carcasses of good quality. No difference existed between the average results of pigs fattened on separated milk, buttermilk, or whey, though fairly wide variations, in quality were apparent in the pigs fattened on any one type of byproduct. These latter were probably due to type differences — i.e., Plate I: Lots P and Sof the same cross fattened on buttermilk alone. It is possible also that the excessive fatness recorded in some lots was due to excessive feeding during the latter stages of growth(7, 8). Little precise information on the effect of small variations in feeding practice can be gathered from consideration of even large numbers of pigs uncontrolled for other factors productive of material effects upon quality. Specially designed feeding trials are essential for this class of work. The Importance of Length of Loin. A representative number of unselected bacon-sides from seven of the major supply countries in the United Kingdom bacon trade weremeasured in conformity with the method used throughout this investigation (1). The results show that New Zealand bacon pigs are shorter at all weights than those from competing countries. Danish pigs have long been recognized as of outstanding length,, but it is of interest to record the very excellent figures of Canadian products as coming on to the market at the present time. Canada has concentrated on improvement of this character during the last ten years by the adoption of special breeding and selection methods.. The marked success which has attended her efforts in this direction suggests that her methods used merit serious attention by the NewZealand producer. The certificate-of-performance scheme for the improvement of pedigree pigs; instituted by the Manawatu-Oroua Pig Recording and Development Club in 1934, is based on the Canadian system, and offers to New Zealand pig-breeders a sound method of improvement of carcass-quality. Commercial Grading Results. In order to obtain an indication of the value of the pigs as. assessed by commercial grading standards, all the carcasses studied in this investigation Were graded also by the voluntary system in use at the export works concerned, and by the official gradingstandards in force in New Zealand in respect to bacon pigs used for both, export and local consumption. In England the carcasses were also graded, under the English official grading scheme at that time in operation.. The results under the New Zealand and English official systems . arereported in Table V.

At first. sight the results under the English grading system are very pleasing, indicating as they do that even a larger proportion •of the New Zealand carcasses reach the top two grades than many -English pigs as indicated by published figures. The results are rather misleading, however, since the English standards do not involve -length of middle in which New Zealand pigs notably fail. Again the fact that only 30 per cent, of the New Zealand pigs were -able to be graded under the English scheme owing to the minimum weight-limit of 140 lb. reduces the value of the comparison. The New Zealand grading results, which include “ length standards/’ are probably more in keeping with the carcass value of the pigs. If “ first grade ”by this system be considered equivalent to grades A and B under the former system, it is clear that the length factor has been responsible for fewer pigs grading first in New Zealand. It is of interest also to record that the weightlength relationship previously noted is reflected in the commercial .-grading results when length is a factor, 65 per cent, of pigs below 140 lb. in weight, grading first, as compared with only 25 per cent, ■on pigs over 140 lb. Increased proportion of fat in the heavier •carassses also played a part in this respect. Summary. . Considerable improvement is necessary in the present type of bacon pig exported from New Zealand if a high quality-status on the United Kingdom market is the objective of producers. Shortness in length of loin is revealed as the most serious weakness. This is more apparent at high bacon-weights than at low, and points to the desirability from the quality viewpoint of -marketing the present type of relatively. short pig at weights below 140 lb. Associated with this deficiency in length is a tendency toward overfatness. This is also correlated with carcass-weight and is penalizing to heavier carcasses, though the disadvantage of slaughter ■at weights above 140 lb. is not so acute as in the case of length. Hams, shoulders, eye of loin (indicating proportion of lean meat), -length of legs, and streak, attain a reasonably high standard on the average, though some types of pigs are defective in one or more of these characters. There is little difference between the popular breeds and crosses •in carcass-quality as a whole, though they may vary significantly in efficiency in respect to individual quality-points. The Tamworth - Berkshire-cross pigs are too short in length of loin, while the Large . White crosses are superior to others in this quality as well as in proportion of fat, though defective in other -qualities. Differences within each breed and cross are very marked and point to the existence of suitable and unsuitable bacon strains. 'Selection within these on a carcass-quality basis is the logical line •of attack in an improvement policy. References. (1) Davidson, Hammond, Swain, and Wright : Pig Breeders’ Annual, 1936-37. (2) Hammond : Empire Jn. Exp. Agr., HI, 9, 5 ; 1935. (3) Callow : Empire Jn. Exp. Agr., 111, 9, 90 ; 1935. (4) McMeekan : N.Z. Jn. Agr., 52, 5, 278-289 ; 1936. .. . (5) Hammond .: Jn. Royal Agr. Soc. Eng., 93; 1932. (6) Pig Breeders’ Annual, 28 ; 1933-34. (7) Mansfield and Trehane : Jn. Roy. Agr. Soc., 137 ; 1936. (8) Fishwick Pig Breeders’ Annual, 115 ; 1936-37. ■

* Official Government standards. f Standards in force 1935-36 under British Pig MarketingScheme. ■

Source of Pigs. Shipment Year. Number of Carcasses examined. Number of Carcasses exported. Number of Farmers or Lots. Number of Breeds or Crosses. Farmers 1935 132 118 18 7 T.936 II II I 2 .. T936 II II I 2 Experimental 1935 80 66 8 2 ,, 1936 1936 40 40 36 . 36 5 5 2 2 Total .. 263 231 32 9

Table I.Source and Number of Pigs.

Individual Breeders’ Points. Hams. Shoulders. Streak. of Loin. Fat. Length Loin. ofLength Leg. Total Breeders’ Points. Possible marks 8 7 12 12 28 28 20 20 20 20 5 5 100 100 Code Letter. Average Weight. Percentage of Possible Marks (Average).*

Table II. Summary of Carcass-quality Results : Individual Farmers’ Lots and “Breed or Cross” Groups.

J. 2 126 lb. 82 79 88 .79 78 53 90 75 P. 18 136 lb. 72 •84 81 69 78 53 42 69. FT. 93 • • 137 lb. 77 75 92 57 78 27 • 66 63. H. 6 127 lb. 65 84 89 61 80 33 30 63. L-4 •• 119 lb. 66 7i 88 43 74 54 70 62 E. 6 137 lb. 86 86 89 57 47 46 67 61 f. 7 128 lb. Qi 7i 89 52 54 3i 89 59 G. 7 142 lb. 61 86 53 63 65 35 5i 58 S. 6 144 lb. 80 76 79 37 26 15 93 44 Totals . . 136 lb. 75 78. 85 58 70 35 62 62

Tamworth x Berkshire Cross (Number of Carcasses, 149)

M. 8 134 lb. 72 77 88 58 88 57 33 69 C-3 125 lb. 67 95 89 35 82 58 33 62 K. 6 126 lb. 46 84 7i 46 84 57 20 60 B. 8 ■ . . 134 lb. 125 lb. 126 ]b. 132 lb. 72 67 46 lb. 65 ■ 77 95 84 65 80 88 89 7i 80 88 58 35 46 . 88 32 8882 84 32 76 57 58 57 76 46 33 33 20 46 49 69 62. 60 49 57 57 Totals . . 130 lb. lb. 62 62 82 82 84 84 43 43 83 83 55 55 33 33 62 62

Tamworth X Large White Cross (Number of Carcasses, 25)

A. 4 C2. 6 .. N. 7 FT. 20 131 lb. 145 lb. 143 lb. 142 lb. 9i 95 65 63 90 88 84 77 65 66 79 87 61 63 80 50 85 87 63 69 33 30 22 28 80 60 46 44 66 66 62 57 Totals . . 140 lb. 75 83 77 62 74 28 53 62

Tamworth x Large Black Cross (Number of Carcasses, 37).

R. 9 C. 6 145 lb. 144 lb. 79 08 70 100 75 69 54 36 82 87 47 18 62 . 60 63 57 Totals . . 145 lb. 86 82 72 47 83 35 61 60

Large White X Berkshire Cross (Number of Carcasses, 15).

T. 6 147 lb. 78 8l 56 41 64 71 42 60 D.5 136 lb. 65 80 77 52 73 64 24 63 Q-7 ■135 lb. 68 71 77 56 ■ «7 43 29 63 * cc Breeders’ marks’ only. See Refe rence(i).

Pure Breeds (T = Large White; D = Tam worth ; Q = Large Black) (Number of Carcases, 18.)

Weight-range. Number • of Pigs. Standard Length for , Weight. Actual Length for Weight. Deficieny in Length. Marks awarded. Standard Increase with Weight. Actual Increase with Weight. lb. Mm. Mm. Mm. Per Cent. Mm. Mm. II5-II9 7 • : 755 710 45 55 0 O 120-124 12 765 • 716 49. 50 10 6 125-129 16 ■ 775 - 715 ■ 60 40 20 5 130-134 46 785 726 59 40 30 16 135-139 45 795 732 62 35 40 / 22 140-144 .. 41 805 730 75 25 50 20 i45-i49 35 ■815 736 ■ ' 79 20 60 26 150-154 19 ■ 825 733 92 10 70 23 155-160 6 835 ' 732 103 0 80 22

Table III. —-Changes in “ Length of Loin ” with Increase in Weight.

Weight-range.* Number of Pigs. “ Eye of Loin.” “ Fat at Point of Eye.” Thickness. Marks. Thickness. Marks. . Standard Thickness. lb. Mm. Per Cent. Mm. Per Cent. Mm. II5-II9 7 38-0 70 22-0 98 21-75 120-124 .. .. 12 40-0 75 24-4 92 22-25 125-129 16 42 -o 85 24-7 90 . 22-75 I3O-I34 44 41-0 80 .25'4 92 23-25 135-139 4i 40-0 75 . 26'5 88 23-75 140-144 .. 30 41-0 80 28 • I 85 24-25 145-149 21 43-o 85 28 • 85 ■ 24-75 I5O-I54 8 43'0 85 29’4 . 82 25-25 155-160 . . . . 3 39'0 65 32-0 60 25 • 75

Table IV. —Changes in “ Fat at Point of Eye ” and in “ Thickness of Eye ’’ with Increase in- Weight.

Grading System .. New Zealand.* English Bacon.f Grade .. .. .. First. Second. A. B. C. D. Per Cent. Per Cent. Per Cent. Per Cent. Per Cent. Per Cent. Under 140 lb. . 62 38 Over 140 lb. .. • 25 75 ' 40 28 21 II All carcasses .. Per Cent. 6'2 25 45 Per Cent. 38 75 55 Per Cent. 4° Per Cent. 28 Per Cent. 21 Per Cent. II

Table V. —Commercial Grading Results.