Energy requirements for ingestion and standing were determined in open-circuit respiration chambers with four ruminally cannulated German Red Pied steers weighing 617 +/- 53 kg of BW (mean +/- SD). The requirement for standing over lying was derived by regressing heat production on time spent standing within 2-h periods when no feed was offered to avoid any interference with eating activity, and amounted to 14 kJ/(d x kg of BW). The energy requirement for ingestion was determined by calculating the difference between heat production during a 2-h period without feed and during a consecutive 2-h period in which straw of different particle sizes, fresh and conserved grass, or rolled barley were offered for ad libitum intake. Before measurements, the rumens of the steers were emptied, washed, and filled with a buffer solution to avoid heat production by metabolism of absorbed nutrients from the feed ingested during the experimental periods. The mean value for all feeds tested was 20 J/(min of ingestion x kg BW). Relating heat production to the amount of DM or fiber ingested did not decrease variation among feeds. This confirms the observations of earlier studies, that energy requirement for ingestion is mainly determined by time spent eating. Results of additional measurements, in which the same amounts of the respective feeds ingested in preceding periods were put into the emptied rumens via the cannulas, showed that the presence of the feed in the rumen did not increase heat production, indicating that the increment of heat production during eating is mainly caused by ingesting and chewing the feed. Further measurements in the same animals with an ingesta-filled rumen showed that ingestion of straw led to an increase in heat production per minute of chewing similar to those with emptied rumens, which confirms the validity of the experimental procedure using ruminally emptied animals to determine the energy requirement for ingestion.
The objective of this trial was to quantify the influence of a varied dietary crude protein content supplying equal amounts of limiting essential amino acids on parameters of energy metabolism. A total of 16 castrated male pigs were allocated to four dietary treatments and subjected to measurements of N‐balance and gas exchange at approximately 65 and 85 kg live weight. Two rations formulated to be isoenergetic differed in crude protein content (CP) and were offered at two feeding levels. At 85 kg, rations with a lower CP content were used. Multiple regression analysis was used to determine the effects of CP and those of live weight and metabolizable energy intake (IME). A rise in CP significantly increased energy losses via urine and the energy retained as protein (RPE), while the energy retained as fat was significantly reduced. Energy retention tended (P<0.1) to decrease, while related to IME the reduction was non significant. The proportion of RPE in energy gain was significantly improved. Possible mechanisms for this shift towards reduced fat and energy retention at higher protein intakes are discussed. It is concluded that in practical feeding, rations with a lower CP content should be fed restrictively or be reduced in energy content to avoid excessive carcass fatness.
Two studies, arranged according to a 4 × 4 Latin square design, were conducted to assess effects of dietary acidification on fungal 3-phytase (PHY) efficacy in growing pigs. In Exp. 1, effects of supplementing 500 units/kg feed of PHY and 4.7 g/kg HCOOH either alone or in combination on the use of P and Zn in growing pigs fed a pelleted diet based on wheat (Triticum aestivum), barley (Hordeum vulgare), and soybean (Glycine max) meal were investigated. In Exp. 2 the same dietary treatments were fed except that PHY supplementation was increased to 1000 units/kg. In both experiments, PHY supplementation increased (P < 0.05) P digestibility and retention. A PHY × HCOOH supplementation interaction on P balance was observed (P < 0.05), indicating that the combination of the additives may increase P digestibility and retention. Effects of HCOOH and PHY on Zn use followed a similar pattern. Supplementation of 1000 units/kg of PHY further increased P and Zn retention compared to supplementation of 500 units/kg. In conclusion, the present study indicated that HCOOH supplementation to diets with microbial PHY may increase PHY efficacy.
The purpose was to assess the effect of exchanging crude protein (CP) of soybean meal (SBM) with red clover silage (RCS) in total mixed rations (TMR) on ruminal degradation and intestinal digestibility (ID) of essential amino acids (EAA). Four TMR and their individual feed components were studied. The TMR were composed of forage and concentrates (75:25), with proportions of RCS in TMR of 0.15, 0.30, 0.45, and 0.60 on a dry matter basis, resulting in diet groups RCS15, RCS30, RCS45, and RCS60, respectively. The ruminal degradation of EAA was determined using the nylon bag technique. For this, samples of TMR and their individual feed components were ruminally incubated for 16 h. The feed residues of TMR obtained after 16 h of incubation were used for the determination of ID of EAA using the mobile-bag technique. Increasing RCS and reducing SBM proportions linearly increased (
The positive relationship between fecal CP concentration and diet OM digestibility in cattle, which is based on increasing undigested microbial CP and decreasing fecal OM as OM digestibility increases, may be used as an indirect method for estimating diet OM digestibility from fecal CP concentration. Results of digestibility trials (445 individual observations) conducted at Hohenheim and Braunschweig, Germany, and at Gumpenstein, Austria, were used to study the relationship between CP concentration in feces (x, g/kg OM) and OM digestibility (y, %). The best fit was obtained with the curvilinear relationship y = ai −107.7e(−0.01515 × x), with a1 = 79.76 and a2 = 72.86 (R2 = 0.82; residual SD = 2.7; SE = 0.13), which takes into account the effects of location (i = 1 for Braunschweig and Hohenheim, and i = 2 for Gumpenstein). Dietary CP and crude fat concentration, and DMI had no effect on fecal CP content, whereas crude fiber content, proportion of concentrate in the diet, and forage type significantly affected CP concentration in feces; however, the magnitude of these effects was less than 2 percentage units, and the direction of the effect of proportion of concentrate in the diet was not uniform. The curvilinear relationship between fecal CP concentration (observed range, 100 to 300 g/kg of OM) and diet OM digestibility (observed range = 57 to 80%) may be used to estimate diet OM digestibility, particularly for field trials, as it requires no feed samples and does not physically restrict the animal.
Summary Young pigs (body weight 15–25 kg) were used to study the effect of graded levels of tryptophan supplementation to a diet containing 2.5 g tryptophan/kg dry matter (DM) and having a tryptophan to lysine ratio of 0.17 under restricted and unrestricted feeding conditions. Ad libitum feed intake and growth rate were 0.99 kg DM/day and 0.84 kg/day, respectively, and were not affected by supplementation of 0.2, 0.4, 0.6, 0.8 and 1.0 g tryptophan/kg diet. In restricted‐fed piglets (80% of ad libitum intake) tryptophan supplementation did not improve growth rate. Therefore, greater optimum tryptophan to lysine ratios for young fast growing pigs, as concluded from results of some recently published studies in contrast to results of other studies, could not be confirmed. Possible reasons for discrepancies in published values for optimum tryptophan supply are briefly discussed. In accordance with general recommendations given in the literature, it can be concluded that a tryptophan to lysine ratio between 0.17 and 0.18 is sufficient to reach high feed intake and high growth rate in young pigs, when adequately supplied with lysine and other amino acids.
Measurements of morphological and biochemical parameters in subcutaneous adipose tissue as well as investigations of energy metabolism and fat deposition of 89 male castrated pigs were performed. Breeding lines of swine (German Landrace) had been selected through 8 generations for high ("E(+)-Line") and low ("E(-)-Line") levels of NADPH-generating dehydrogenases. A control group ("K.") without selection was closely paralleled. For 21 days the animals were kept under feeding experiments within 2 sectors of growing period (67 kg, 85 kg body mass), and biopsies of backfat were examined subsequently. The inner layer of subcutaneous adipose tissue showed constantly bigger fat cells than the outer layer. The fat cell size increased generally with fattening and body mass respectively. The cellularity of adipose tissue was dependent significantly on the percentage of the very small fat cells measured up to 30 microns diameter (= "PKF30"). The breeding lines differed slightly with respect to their cellularity: The inner layer showed the gradation E+ greater than K. greater than E- concerning fat cell volumes and fat cell surfaces respectively. The PKF30 correlated significantly with food energy level as well as with the respirationally examined protein retention, particularly in inner layers of younger animals. Relations to the fat deposition (examined respirationally or with the D2O-Method and after slaughter respectively) were recognized, not showing validity for all cases. The parameters of lipogenic activity tested by tissue slice preparations and homogenates respectively correlated negatively with average fat cell size.(ABSTRACT TRUNCATED AT 250 WORDS)
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