Lower Food Conversion Ratio Research Articles

The effects of carbadox on the performance and carcass characteristics of early-weaned pigs given high- and low-protein diets

ABSTRACTThirty-six male pigs weaned at 28 days of age were used to study the effects of methyl-3-(2- quinoxalinylmethylene) carbazate-N1, N4-dioxide (carbadox) in high- and low-protein diets on the performance of pigs growing between 7 and 32 kg live weight, and on carcass characteristics at the latter weight.The inclusion of carbadox (55 mg/kg) in a high-protein diet containing 195 g crude protein per kg and 10·2 g lysine per kg had no effect on performance or on carcass characteristics. Pigs offered the high-protein diets grew more rapidly, had a lower food conversion ratio and were leaner at 32 kg live weight than those offered a lowprotein diet containing 146g crude protein per kg and 6·0 g lysine per kg. Supplementation of the low-protein diet with lysine (4·2 g/kg) had no effect on performance or carcass characteristics but the inclusion of carbadox in the low-protein diet increased growth performance and reduced carcass backfat measurements at 32 kg. However, the performance was inferior, and the backfat thickness greater, compared with the high-protein diets. On the other hand, supplementation of the low-protein diet with lysine plus carbadox raised growth performance and reduced carcass backfat measurements to the levels exhibited on the high protein diets.

The effect of protein nutrition between 5–5 and 20 kg live weight on the subsequent performance and carcass quality of pigs

ABSTRACTThirty male pigs weaned at 5·5 kg were used to determine the effect of diets with 164, 192 and 219 g/kg crude protein offered ad libitum to 20 kg live weight on performance and carcass characteristics during this initial phase of growth and during the period subsequent to 20 kg live weight when all pigs were fed on a diet with 181 g/kg crude protein in restrictive amounts. Between 5·5 and 20 kg live weight, pigs offered the diet with 164 g/kg crude protein grew significantly more slowly and had a significantly poorer food conversion ratio than pigs offered the two higher protein diets. Both linear fat measurement and the proportion of ether extractable material in the carcass at 20 kg live weight decreased significantly with each increase in dietary protein. Pigs offered the 164 g/kg protein diet during the initial treatment period tended to grow faster subsequent to 20 kg and during the live-weight period 20 to 45 kg had a significantly lower food conversion ratio than pigs previously offered the two higher protein diets. Over the entire production period, 5·5 to 70 kg, there were no significant differences between treatments. Likewise there were no significant differences in carcass quality parameters between treatments at 70 kg live weight.

Raw and steam-pelleted cassava, sweet potato and yam cayenensis as starch sources for ruminant and chicken diets

Three tropical tubers, raw or processed by steam-pelleting, were studied in the rumen in vitro or in the chicken in vivo in order to determine the effects of the nature and of the treatment of the tubers on urea utilization by rumen microflora, starch breakdown in the crop and the performance of growing chickens. Starch of cassava ( Manihot utilissima) and of sweet potato ( Ipomea batata) is characterised by an X-ray diffraction pattern of the A-type and is therefore similar to starch of cereals. In vitro these starches were well broken down in the presence of α-amylase from B. subtilis, and were good sources of energy for rumen microbial growth; in vivo they were completely digested by growing chickens. Compared to cassava, the fermentation of sweet potato in rumen and crop led to increased acidity. The cassava diet gave a better nitrogen retention and growth performance associated with higher food intake. In contrast, starch of yam ( Dioscorea cayenensis) which is characterized by an X-ray diffraction pattern of the B-type, and by large granules like potato starch, was less susceptible to α-amylase and promoted lower microbial proteosynthesis in vitro. Starch from a yam diet was more slowly degraded in the crop and its overall digestibility was only 83%. Yam reduced feed intake and gave lower nitrogen retention and lower food conversion ratio and consequently poor growth. The steam-pelleting treatment increased starch availability and permitted better urea utilization by rumen microflora. It improved N retention and feed efficiency of chicken diets, although not significantly. The greatest effect of the treatment was observed with yam. In conclusion, the digestibility of a given starch seems to be related to its structure, characterized by the type of X-ray diffraction pattern, which could be a help in tuber selection for animal nutrition. Simple processing such as steam-pelleting may improve the nutritive value of a tuber, especially when its starch has a B-type crystallinity.

The relative protein and energy requirements of boars, gilts and barrows

Two experiments were conducted to study the response of boars, gilts and barrows to increasing levels of dietary crude protein and digestible energy. In the first experiment boars, gilts and barrows were fed diets ranging in crude protein from 14.6 to 22.7 per cent in restrictive amounts between 20 and 70 kg liveweight. Growth rate and food conversion efficiency measurements ranked the sexes in order of superiority as boars, gilts and barrows. Boars contained more lean in their hams than gilts or barrows and had lower back fat measurements than barrows. Although analysis of variance indicated there was no significant sex by protein interaction, the multiple regression equations of growth rate and the proportion of lean in the ham for the three sexes were significantly different from one another. The response curves based on the regression equations indicated that for optimum growth, boars and gilts required 19.6 per cent crude protein whereas barrows required only 18.4 per cent crude protein. The proportion of lean in the ham was maximized with 21 per cent crude protein for boars and 20 per cent crude protein for the gilts and barrows. There was a significant quadratic relationship between economic returns and dietary protein. The relationship was the same for boars and gilts and significantly different from that for barrows; returns were maximized at approximately the same protein level as growth rate for the three sexes. In the second experiment, 30 boars and 30 gilts were allocated to 30 treatment groups involving the two sexes, three levels of digestible energy (14.59, 15.51 and 16.22 MJ kg-1) and five levels of crude protein (18.2, 19.4, 20.6, 21.8 and 23.0 per cent). All diets were fed restrictively and pig performance was compared over the liveweight range 20 to 80 kg. Boars grew significantly faster, had a significantly lower food conversion ratio and produced leaner carcases than gilts. Increasing the DE level of the diet improved growth rate and food conversion efficiency but reduced carcase quality. Dietary protein level had no effect on any performance or carcase quality measurement.

Efficiency of food conversion and body composition of the preruminant lamb and the young pig.

1. A comparison was made of the efficiency of food conversion and body composition of the preruminant lamb and young pig when offered cow's milk supplemented with minerals and vitamins from 2 to 10 weeks of age.2. The daily voluntary intake of gross energy/kg live weight0·75 of the pigs was significantly greater than that of the lambs. The daily voluntary intake of the lambs decreased from 1895 to 1573 kJ/kg live weight0·75 (453 to 376 kcal/kg0·75) over the experimental period and that for the pigs increased from 2063 to 2519 kJ/kg live weight0·75 (493 to 602 kcal/kg0·75).3. Of the organic matter of the milk, 0·97–0·98 was digested by both species. Food conversion ratio (kg dry matter milk/kg live-weight gain) did not differ between the species when food was given ad lib. but pigs restricted to 80% of voluntary food intake or to 1255 kJ/kg live weight0·75 (300 kcal/kg0·75) had a lower food conversion ratio than lambs similarly restricted in intake.4. A 20% reduction in the voluntary intake of gross energy decreased daily protein deposition in the lambs only but decreased daily fat deposition in both species.