From the individual observations concerning live weight and age during the experimental time (Main Tables p. 159), the means of live weight and daily gain of weight have been calculated for the six rations in question. The correspon-ding values are plotted in Figure 16, and the mean curve is drawn. The values of daily gain for different live weight classes taken from the curve are tabulated in Table 24, together with the daily intake of feed, metabolizable energy (ME) and net energy (NEF). These values are obtained by plotting the figures from Table 16, 17 and 18 against the corresponding live weight, and reading the curves obtained. From these figures the conversion of feed or energy to live weight gain is calculated, as shown in the three last columns in Table 24.
It is obvious that the live weight gain of 250 g in the class from 20 to 30 kg live weight is low, afact which can be explained by the rather low intake of energy in the first balance period. In the following periods the daily gain of live weight increased, ending at 775 g in the live weight class of 80 kg. In average for all compounds the mean gain was 571 g during the experimental time, with a feed conversion ratio increasing from about 2,6 kg feed per kg live weight gain until 3.4.kg, the average being 2.9 kg. Expressed in terms of metabolizable energy 8 Meal was needed for 1 kg of live weight gain from 20 to 30 kg live weight, increasing to 11 Meal ME at 80 kg of live weight, caused by the higher maintenance requirement, and the changes in the body composition, consisting of more fat and less protein and water with increasing age. Using the calculated values for net energy in the rations according to the Rostock-equations (Neh-ring et al. (1970)), it was found, that the requirement per kg live weight in the present investigations was about 6 Meal NEF from 20 to 40 kg live weight, increasing to 7.4 Meal with a daily gain of 775 g at 80 kg live weight.
g 800 700
• | 6 0 0 500
g 400
300 200
• BA+MlorPR
• MA+MlorPR A SO+MI or PR
20 30 40 50 60
Live weight
70 80 1*9
Figure 16.
Daily live weight gain in relation to live weight. Mean of 6 different rations in series C-D-E-F. 1964-1966.
Daglig tilvækst i relation til legemsvægten. Middelværdier for 6 fodertyper i serie C-D-E-F. 1964-1966.
Table 24. Estimation of feed- and energy conversion to kg live weight gain in different live weight classes. Series C-D-E-F. Mean of all compounds
Tabel 24. Beregnet foder- og energiudnytning pr. kg tilvækst indenfor forskellige vægt-klasser. Serie C-D-E-F. Middel for alle undersøgte foderblandinger
Live weight
class kg 20 30 40 50 60 70 80
Daily live weight
gain g 250 435 535 610 670 725 775
Feed kg
0.65 1.05 1.40 1.70 2.00 2.30 2.60
Daily intake of ME Meal
2.00 3.45 4.70 5.80 6.80 7.75 8.55
NEF*) Meal
1.50 2.40 3.20 3.90 4.60 5.20 5.75
Feed kg 2.6 2.4 2.6 2.8 3.0 3.2 3.4
Conversion of feed to kg live weight gain
ME Meal
8.0 7.9 8.8 9.5 10.2 10.7 11.0
NEF*) Meal 6.0 5.5 6.0 6.4 6.9 7.2 7.4
*) Net energy for fattening swine, Nehring et al. (1970)
In the experiment of Vers te gen (1971) a daily live weight gain of 550-600 g was found in pigs from 20 to 100 kg and the feed conversion for the 3 groups of pair was 3.4, 2.9 and 3.2 kg feed pr. kg growth.
The daily live weight gain (corrected) for all pigs, in the trials of Nielsen (1970) was in average 629 g with afeed conversion of 2.77 Sc.f .u. per kg growth.
The somewhat higher live weight gain found, in spite of the lower intake of metabolizable energy than in our experiments (cf. Figure 12), can be explained by the fact, that the trials of Nielsen were carried out with sows as well as with barrows, and the growth of sows is faster than of barrows.
In the experiments oiBreirem (1935) with 5 pigs on low protein and 3 pigs on high protein diet but all on a low intake of metabolizable energy (cf. Figure 12) the mean daily gain in live weight from 20 to 90 kg was only 483 g for the low protein group. For the high protein group on the same intake of ME the daily gain in live weight was in average 567 g. Compared with the results obtained by Nielsen (1970) and by us in the present investigation, the rather low growth in the experiment ofBreirem can be partly explained by the genetic progress in the Danish Landrace with its greater ability to utilize the feed, and partly to the norm used.
A.R.C. (1967) recommends 18.5-20% crude protein up to 45-50 live weight and then 15-16.5% until 90 kg, combined with an increasing intake of energy, starting at 3.0 Meal digestible energy at 20 kg live weight, ending with 9.6 Meal at 90 kg. In the present investigations the norm for intake of protein is close to the A.R.C.-norm, while the intake of energy has been more restricted, especi-ally from 20 to 50 kg, caused by the fear of any feed residue in the balance experiments.
In the publication of Schiemann et al. (1971) an attempt has been made, on the basis of their extensive investigations, to calculate the requirement of net energy (NEF) per. kg growth at different live weight classes and with different daily gain in weight. Comparing the results we have obtained (Table 24) with the values by Schiemann et al. for the same live weight and daily gain af weight, it will be found that our results, starting between 5.5-6.0 and ending with 7.4 Meal NEF per kg growth, are about 12% lower than the figures from Rostock.
The difference was greatest for the lower weight classes, about 18% decreasing to 5% at 80 kg live weight. As the same method of calculation the NEF content in the feed intake has been used, the discrepancy may be explained by genetic differences in the races with a somewhat higher efficiency of the Danish Landrace in utilising the feed, especially as regards protein gain.
CHAPTER 5