Barley fibre and wet distillers’ solubles in the diet of growing cattle Tarja Root Department ofAnimal Science, PO Box 28, FIN-00014 University ofHelsinki, Finland, e-mail: tarja.root@helsinki.fi Pekka Huhtanen Department ofAnimal Science, University of Helsinki, Finland. Current address: Agricultural Research Centre of Finland, Animal Production Research, FIN-31600 Jokioinen, Finland Twenty-eight bulls were used in a 3 x 2 factorial design to study the effects of two by-products from the integrated starch-ethanol process, barley fibre and distillers’ solubles, as supplements for grass silage. The animals were divided into five blocks and slaughtered when the average live weight (LW) of each block reached 500 kg. The three energy supplements were barley (B), a mixture (1:1 on a dry matter (DM) basis) of barley and barley fibre (BF), and barley fibre (F), fed without (DS-) or with (DS+) wet distillers’ solubles (200 g kg' 1 concentrate on DM basis). Concentrates were given at the rate of 95 g DM kg 1 LW06 . Including barley fibre in the diet did not affect feed intake, but distillers’ solubles tended to in- crease both silage and total DM intakes as well as amino acids absorbed in the intestine and energy intake. The protein balance in the rumen increased with the inclusion of barley fibre (PcO.OOl) and distillers’ solubles in the diet (PcO.Ol). Even though barley fibre had lower energy content than bar- ley, it did not affect metabolizable energy (ME) intake markedly. The average daily LW gain of all groups was high, and it was not significantly different for the various supplements. However, towards the end of the experiment the LW gain of bulls fed with barley fibre tended to decrease compared to barley. Feed conversion rates in terms of kg DM and MJ ME kg 1 LW gain and the carcass weight or quality were not significantly affected by the treatments. Key words: barley, bulls, by-products, grass silage, supplementation ntroduction tein feed is rapeseed meal in the feeding of both dairy and beef cattle. The growth rate of bulls given 2-4 kg barley daily and good quality si- lage ad libitum has resulted in high live weight (LW) gains which are difficult to improve with In Finland the usual concentrate supplement to grass silage is barley and the most common pro- © Agricultural and Food Science in Finland Manuscript received October 1997 357 Voi 7(1998): 357- AGRICULTURAL AND FOOD SCIENCE IN FINLAND Root, T. & Huhtanen, P. Barleyfibre and wet distillers’ solubles in the dietofgrowing cattle protein supplementation or by other energy sup- plements (Kay and Harland 1988, Aronen and Vanhatalo 1992). However, it is necessary to study alternative energy and protein sources for environmental and economical reasons. The integrated starch-ethanol process gives many by-products that are suitable for animal feeding (Näsi 1988), of which barley fibre (BF) and wet distillers’ solubles (WDS) are most com- monly used. Barley fibre consists of the cell-wall fraction of endosperm with 550 g neutral deter- gent fibre (NDF) and 90 g starch per kg dry mat- ter (DM). Barley fibre has not been studied wide- ly in the feeding of growing cattle, but in one study (Huhtanen et al. 1989) replacing barley with barley fibre decreased the daily gain of growing bulls by ca. 70 g d l . The calculated en- ergy valueof barley fibre was about 90% that of barley. Results with dairy cows showed that there was either no difference in the milk yield ofcows given barley or barley fibre (Huhtanen et al. 1988) or milk yield was higher withbarley fibre diets (Ala-Seppälä et al. 1988). In a study with cannulated animals barley fibre increased the proportion of propionate in rumen volatile fatty acids (VFA) and duodenal non-ammonia nitro- gen (NAN) flow compared with barley (Huh- tanen 1992). Another by-product from integrated starch- ethanol production is wet distillers’ solubles, the value of which, as a protein source for growing cattle, has not been studied. Compared with bar- ley and barley fibre, the crude protein content in distillers’ solubles is high, approximately 300 g (kg DM) 1 . In addition, having a high lactic acid content (150 g (kg DM) 1 ), wet distillers’ solu- bles tend to increase the proportion of propionic acid in the rumen VFA (Huhtanen 1992), which can have positive effects in the feeding of grow- ing cattle. When replacing barley, wet distillers’ solubles have been shown to increase milk yield, mainly due to increased feed intake and metab- olizable energy (ME) supply when wet distill- ers’ solubles were included in the diet (Huhtanen and Miettinen 1992). Since the demand for both glucose and protein is higher for milk produc- tion than for growth, dairy cows did benefit from barley fibre and WDS because they balanced nutrient supply and increased NAN flow in the duodenum. The purpose of this trial was to study the ef- fects of replacing barley with barley fibre, with or without distillers’ solubles, on the perform- ance of bulls given grass silage ad libitum. Wet distillers’ solubles replaced part of the barley and/or barley fibre. Material and methods Animals, diets and experimental procedures The animals used in the trial were 15 Friesian, 8 Ayrshire and 5 Hereford bulls with a mean ini- tial live weight of 205 (SE 4.6) kg. They were divided into five blocks by breed and LW, and randomly assigned to treatments within each block. The Hereford block included one Friesian animal, and each of the two Friesian blocks had one Ayrshire animal. The bulls were housed in a tie-up barn and individually fed twice a day. The animals were weighed on two consecutive days at the beginning and the end of the experiment, and at 28-day interval during the trial. LW gains were calculated for each animal both by the dif- ference method and with a second-degree poly- nomial regression of LW on time. A 3 x 2 factorial design was used to study the effects of by-products from the integrated starch-ethanol process (Näsi 1988) as supple- ments to grass silage. The three energy supple- ments were barley (B), a mixture (1:1 on dry matter (DM) basis) of barley and barley fibre (BF), and barley fibre (F), fed without (DS-) or with (DS+) wet distillers’ solubles (200 g kg 1 concentrate on DM basis). Concentrates were given at a rate of 95 g DM kg' 1 LW 06 based on the LW of the animals at the beginning of each experimental period (28 d) to maintain a con- stant forage to concentrate ratio throughout the experiment. The daily ration also included 150 g of a mineral mixture. To improve palatability, 10-20% distillers’ solubles was added to the 358 AGRICULTURAL AND FOOD SCIENCE IN FINLAND barley fibre during the production process, and it was fed to the animals in pelleted form. Wet distillers’ solubles contained sodium benzoate (E211) 1.5 g kg’ 1 as a preservative, and it was delivered to the farm every second week (300 1). To reduce the degradability of protein in the ru- men, wet distillers’ solubles were treated with a solution (Graintona) containing formalin (410 g kg '), short-chain fatty acids (430 gkg 1 ), lignone sulphonate (75 g kg 1 ) and urea+utropine stabi- lizer (75 g kg ') (European Patent Office 1982). The application rate of Graintona was 3.7 1 tn 1 . Barley, barley fibre and distillers’ solubles were weighed separately and mixed before feeding. Grass silage (GS) was prepared from the prima- ry growth of a timothy-meadow fescue sward, treated with a formic acid-based additive (800 g formic acid kg’ 1 , 20 g orthophosphoric acid kg ') at the rate of 4 1 t 1 and ensiled in bunker silos. Silage was fed ad libitum. When the average LW of cattle in each block of animals reached 500 kg, they were slaugh- tered, and thus the time in the trial ranged be- tween 168 to 280 days. Dressing percentages were calculated as a proportion of hot carcass weight to final live weight. The carcasses were visually graded for conformation and fatness using the carcass classification scheme ofFinn- ish commercial slaughter houses. Sampling and analytical methods Silage, barley and barley fibre were sampled weekly and analyzed for DM. Distillers’ solu- bles was sampled once every fortnight. Silage samples were pooled over four weeks and con- centrates over eight weeks for analyses. The DM content of feeds was determined by oven drying at 105°C for 24 h. Feed analyses were made according to standard procedures (AOAC 1984). The amount of ether extract was determined after acid (HCI) hydrolysis. Silage DM content was corrected for volatile losses of lactic acid, VFA and ammonia as described by Porter et al. (1984). Neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid de- tergent lignin (ADL) were analysed according to Goering and Van Soest (1970) with the modi- fication by Robertson and Van Soest (1977) for barley. Ammonia N (McCullough 1967), lactic acid (Barker and Summerson 1941), sugars (Nel- son 1944) and VFA (Huida 1973) were analysed and pH measured from fresh silage and distill- ers’ solubles samples. Calculation of results and statistical analyses Energy and protein requirements were calculated for each animal for every 28 d experimental pe- riod. Requirements for the ME (Finnish feed unit (FFU), which is based on metabolizable ener- gy), was calculated according to ARC (1980) (Tuori et al. 1996). Protein requirements were calculated according to the Nordic protein eval- uation system modified for Finnish conditions (Tuori et al. 1996). The feeding values for the experimental feeds were calculated according to MAFF (1975) and Tuori et al. (1996). The car- cass gain of the animals was calculated assum- ing that the carcass weight at the beginning of the experiment was LW x 0.50. The model for analysing data was yijk| =p + E + P + (EP) +B, + e... „ where E, P and B arei j v '|J k ijkr ’ the effects of energy supplement, wet distillers’ solubles and block. The effect of the energy sup- plement was further partitioned into linear and quadratic effects of the replacement of barley with barley fibre by using polynomial contrasts (Snedecor and Cochran 1989). The interactions were not statistically significant (P>o.lo for all parameters), and therefore the results are pre- sented only for the main effects of the energy and protein supplements. Results The mean chemical compositon and estimated feeding values of the feeds are presented in Ta- ble 1. The silage used was of good quality in 359 Vol. 7(1998): 357-366. AGRICULTURAL AND FOOD SCIENCE IN FINLAND Root, T. & Huhtanen, P. Barley fibre and wet distillers’solubles in the dietofgrowing cattle Table 1.Chemical composition of the feeds (g kg 1 dry matter) and estimated feed values. Grass Barley Barley Distillers’ silage fibre solubles Dry matter(g kg' l ) 282 864 907 330 In dry matter (g kg l ) Ash 88 26 37 127 Crude protein 125 113 170 273 Ether extract 36 33 70 68 Crude fibre 279 52 167 13 N-free extract 472 776 556 518 NDF 508 214 632 ADF 290 55 198 ADL 22 6 27 Feed values ME, MJ (kg DM) 1 10.5 13.8 11.7 12.4 AAT, g (kg DM) 1 79 103 107 115 PBV, g (kg DM) I -10 -56 I 92 NDF = neutral detergent fibre, ADL = acid detergent lignin AAT = amino acids absorbed in the intestine, PBV = protein balance in the rumen In silage: pH 4.08; in DM (g kg '): lactic acid 44, acetic acid 17, butyric acid 0.3, water soluble carbohy- drates 69; in total N (g kg '): NH,-N 41, soluble N 585; D-value 0.655 In distillers’ solubles: in DM (g kg '): lactic acid 151 terms of both fermentation characteristics (41 g NH3 -N kg ' total N) and D-value (0.655, based on in vitro digestibility (Tilley and Terry 1963)). Barley fibre and wet distillers’ solubles contained almost twice as much fat as barley because the fat from barley does not separate during the pro- duction process but accumulates into the by- products. The calculated energy value of barley was 18% higher than that of barley fibre, but barley fibre contained slightly more AAT (ami- no acids absorbed in the intestine) (107 vs. 103 g (kg DM) 1 ) and its PBV (protein balance in the rumen) value was higher (1 vs. -56 g (kg DM) 1 ) compared with barley. Distillers’ solubles had a high PBV-value (92 g (kg DM) 1 ) and contained 151 g lactic acid (kg DM) 1 . The inclusion ofdistillers’ solubles to the diet had a tendency to increase silage and total DM as well as AAT and energy intake (Table 2). However, these effects were not statistically sig- nificant. The palatability of barley fibre was good, since the average concentrate intake was not affected by the energy supplement. The pro- tein balance in the rumen (PBV) increased with barley fibre (PcO.001) and distillers’ solubles in the diet (P<0.01). Even though barley fibre had lower energy values than barley, this fact did not affect the ME intake markedly because of slight- ly higher silage DM intake (Table 2). The average daily live weight gain of all groups was high, and was not significantly af- fected by any supplement. The feed-conversion rates in terms ofkg DM and MJ ME per kg LW gain were not significantly affected. There were no significant differences in carcass weight or quality between the treatments (Table 3). The growth rates of bulls given BE and F di- ets were higher than with the B diet in the be- ginning of the trial (LW <350 kg) but the differ- ence was not statistically significant. Inclusion ofbarley fibre in the diet decreased the daily gain towards the end of the experiment (P<0.10) (Ta- ble 4). Inclusion ofdistillers’ solubles in the diet did not affect the growth rate. The dry matter intake was not affected by the energy supplement throughout the trial, but distillers’ solubles in- 360 AGRICULTURAL AND FOOD SCIENCE IN FINLAND Table 2. Feed intake (kg dry matterd 1) and nutrient consumption. Energy supplement DS SEM 1 Statistical significance2 18 df B BE F - + energy linear DS Intake, (kg dry matter d' 1) Grass silage 4.54 4.67 4.82 4.53 4.81 0.173 Concentrates 2.97 3.07 3.00 2.93 3.09 0.127 Total DM intake 7.51 7.74 7.82 7.46 7.90 0.249 DM intake g kg'W° 75 94.0 97.5 97.7 94.2 98.6 1.91 ME, MJ d 1 86.5 86.2 83.7 83.3 87.7 2.76 AAT, g d 1 661 688 695 659 703 22.0 PBV, g d 1 -156 -93 -35 -124 -65 13.2 »�* ** 1 SEM of the energy supplements, SEM of DS is 0.816 x SEM of energy supplements 2 The effect of energy supplement is linear and distillers’ solubles quadratic Significance: o (PcO.10), * (P<0.05), **(P