Scholarly article on topic 'Effect of ground corn cobs as a fiber source in total mixed ration on feed intake, milk yield and milk composition in tropical lactating crossbred Holstein cows'

Effect of ground corn cobs as a fiber source in total mixed ration on feed intake, milk yield and milk composition in tropical lactating crossbred Holstein cows Academic research paper on "Animal and dairy science"

CC BY-NC-ND
0
0
Share paper
Academic journal
Animal Nutrition
OECD Field of science
Keywords
{"Dairy cow" / "Ground corn cob" / "Rice straw" / "Rumen fermentation" / "Tropical area"}

Abstract of research paper on Animal and dairy science, author of scientific article — Chalong Wachirapakorn, Krung Pilachai, Metha Wanapat, Pawadee Pakdee, Anusorn Cherdthong

Abstract The aim of this study was to evaluate the effect of ground corn cobs (GCC) as a sole fiber source in total mixed ration (TMR) on feed intake, milk yield and milk composition in tropical lactating crossbred Holstein cows. Four multiparous crossbreds Holstein Friesian dairy cows with an initial body weight (BW) of 415.5 ± 26.20 kg were used in a 4 × 4 Latin square design. The dietary treatments of TMR contained a roughage-to-concentrate ratio of 40:60. The roughage source was used at different ratios of GCC to rice straw (RS) at 100:0, 82.5:17.5, 67.5:32.5, and 50:50 for TMR1 to TMR4, respectively. The results revealed significant improvements in intake of dry matter, protein, neutral detergent fiber (NDF) and metabolizable energy (ME) for TMR1 and TMR2 (P < 0.05), while the digestibility of nutrients was not altered by the treatments (P ≥ 0.05). Ground corn cobs was used for up to 100% of the total roughage without affecting milk production. Moreover, ruminal pH, temperature, ammonia-nitrogen (NH3 N) and volatile fatty acid (VFA) concentrations were not impacted by the treatments (P > 0.05). However, milk yield was significantly different among the GCC:RS ratios (P < 0.05) and was the highest in TMR1 and TMR2 (13.1 kg/d), while the milk compositions were not changed (P > 0.05). The results imply that using GCC as a whole roughage source significantly improved nutrients intake and milk yield in dairy cows raised in tropical areas.

Academic research paper on topic "Effect of ground corn cobs as a fiber source in total mixed ration on feed intake, milk yield and milk composition in tropical lactating crossbred Holstein cows"

Accepted Manuscript

Effect of ground corn cobs as a fiber source in total mixed ration on feed intake, milk yield and milk composition in tropical lactating crossbred Holstein cows

Chalong Wachirapakorn, Krung Pilachai, Metha Wanapat, Pawadee Pakdee, Anusorn Cherdthong I

S2405-6545(16)30100-7 10.1016/j.aninu.2016.08.007

Reference: ANINU 111

To appear in: Animal Nutrition Journal

Received Date: 15 May 2016 Accepted Date: 16 August 2016

Please cite this article as: Wachirapakorn C, Pilachai K, Wanapat M, Pakdee P, Cherdthong A, Effect of ground corn cobs as a fiber source in total mixed ration on feed intake, milk yield and milk composition in tropical lactating crossbred Holstein cows, Animal Nutrition Journal (2016), doi: 10.1016/ j.aninu.2016.08.007.

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

1 Effect of ground corn cobs as a fiber source in total mixed ration on feed intake, milk

2 yield and milk composition in tropical lactating crossbred Holstein cows

5 Chalong Wachirapakorn^*, Krung Pilachaic, Metha Wanapata,b, Pawadee Pakdeea,b,

6 Anusorn Cherdthonga,b

9 a Department of Animal Science, Faculty of Agriculture, Khon Kaen University,

10 Khon Kaen 40002, Thailand

11 b Tropical Feed Resources Research and Development Center (TROFREC),

12 Department of Animal Science, Faculty of Agriculture, Khon Kaen University,

13 Khon Kaen 40002, Thailand

14 c Faculty of Agricultural Technology, Rajabhat Mahasarakham University,

15 Mahasarakham 44000, Thailand

20 21 22

23 *Corresponding author.

24 E-mail address: chal_whc@kku.ac.th (C. Wachirapakorn)

25 Abstract The aim of this study was to evaluate the effect of ground corn cobs (GCC) as sole

26 fiber source in total mixed ration (TMR) on feed intake, milk yield and milk composition in

27 tropical lactating crossbred Holstein cows. Four multiparous crossbreds Holstein Friesian

28 dairy cows with an initial body weight (BW) of 415.5 ± 26.20 kg were used in a 4X4 Latin

29 square design. The dietary treatments of TMR contained a roughage-to-concentrate ratio of

30 40:60. The roughage source was used at different ratios of GCC to rice straw (RS) at 100:0,

31 82.5:17.5, 67.5:32.5, and 50:50 for TMR1 to TMR 4, respectively. The results revealed

32 significant improvements in intake of dry matter, protein, neutral detergent fiber (NDF) and

33 metabolizable energy (ME) for TMR1 and TMR2 (P < 0.05), while the digestibility of

34 nutrients was not altered by the treatments (P > 0.05). Ground corn cobs was used for up to

35 100% of the total roughage without affecting milk production. Moreover, ruminal pH,

36 temperature, ammonia-nitrogen (NH3-N) and volatile fatty acid (VFA) concentrations were

37 not impacted by the treatments (P > 0.05). However, milk yield was significantly different

38 among the GCCRS ratios (P < 0.05) and was the highest in TMR1 and TMR2 (13.1 kg/d),

39 while the milk compositions were not changed (P > 0.05). The results imply that using GCC

40 as a whole roughage source significantly improved nutrients intake and milk yield in dairy

41 cows raised in tropical areas.

43 Keywords: Dairy cow, Ground corn cob, Rice straw, Rumen fermentation, Tropical area

1. Introduction

Crossbred dairy cows raised in the tropics are normally fed low quality roughages, principally agricultural crop-residues such as rice straw (RS) (Devendra and Chantalakhana, 2002; Wanapat et al., 2015). However, RS is low in nutritive value with low protein (2% to 5% DM), high fiber, with neutral detergent fiber (NDF) > 70%, and DM digestibility < 50%, resulting in low voluntary feed intake (1.5% to 2.0% of BW) (Wanapat and Cherdthong, 2009; Wanapat et al., 2009b). Corn cobs (CC) is a by-product of a major cereal grown worldwide. Since the ratio between corn grain and CC may reach 100:18, a large quantity of CC can be generated (Cao et al., 2004). Corn cobs is a prominent cereal crop byproduct in Thailand, and currently most of these materials are wasted natural resources and also are sources of environmental pollution. Legal steps are already being taken in several countries to ban the burning of CC. Corn cobs are high in cellulose and hemicelluloses, and are potentially valuable sources of roughage for ruminants (Avila-Segura et al., 2011; Van Eylen et al., 2011; Liu et al., 2011). Ground corn cobs (GCC) are a good source of fiber, and when enriched with urea (15 g/kg) and fed to swamp buffaloes, they can be efficiently utilized in the rumen and provide good fermentation end-products (Wanapat et al., 2009a). Emery et al. (1964) reported that dairy cows fed GCC as a roughage source could have improved feed intake and milk yield compared with those fed ground hay. However, no data have been reported on replacing RS by GCC in total mixed ration (TMR) in tropical area. The aim of this study is to evaluate GCC as whole fiber source in TMR on feed intake, milk yield and milk composition in tropical lactating crossbred Holstein cows.

2. Materials and methods

2.1 Animals, experimental design and diets

Four multiparous crossbreds Holstein Friesian (75%) dairy cows with an initial body weight of 415.5 ± 26.20 kg and day-in-milk of 131.8 ± 39.40 d (average milk yield 12.75

kg/d) were used in a 4X4 Latin square design with four treatments. The TMR consisted of roughage and concentrate at a ratio of 40:60. The roughage source used in TMR had different ratios of GCC to RS which were 100:0, 82.5:17.5, 67.5:32.5 and 50:50 in TMR1 to 4, respectively. The GCC and RS were obtained from a local market, and ground to pass through a 1-cm screen using a chopper machine. The roughage was then mixed with concentrate at the ratio of 40:60 using a horizontal feed mixer and fed as a TMR. The composition of dietary treatments, GCC and RS are shown in Table 1.

Cows were housed in individual pens and individually fed TMR at 06:00, 11:00, and 16:00. All cows were fed ad libitum. Clean fresh water and mineral blocks were available during the experiment. The experiment was run in 4 periods. Each period lasted for 21 d, in which the first 14 d was for treatment adaptation, and the last 7 d were used for feed intake measurements and sample collections. Refusals were collected every day, and sampled (10% of refusal weight), and feed offered adjusted 3 times per week to ensure 5% to 10% refusal of the total feed offered. Individual voluntary feed intake was calculated by the difference between offered feed and refusals. Feed samples from offered diet were collected from each experimental period. Body weights were measured at the first and last day of samplings. Milk yield was recorded during the 21d which data reported at the last 7 d of each period. 2.2 Data collection and sampling procedures

The TMR, GCC and RS were sampled daily during the collection period and were composited by period prior to chemical analyses. Feed and fecal samples were collected during the last 7 days of each period. For the last 7 days, fecal samples were collected twice a day by rectal sampling. Fecal sample pools were created by combining samples from last 7 days of each animal. Composited samples were dried at 60 °C, ground (1-mm screen using Cyclotech Mill, Tecator), and then analyzed for DM, ash, organic matter (OM), ether extract (EE), crude protein (CP) content (AOAC, 2000), and NDF and acid detergent fiber (ADF)

(Van Soest et al., 1991), and acid-insoluble ash (AIA). Acid-insoluble ash was used as internal marker to estimate digestibility of nutrients (Van Keulen and Young, 1977). Metabolizable energy (ME) was calculated according to the equation described by Robinson et al. (2004): ME (MJ/kg DM) = 0.82 x [2.4 x CP + 3.9 x EE + 1.8 x the rest of the OM] x in vitro organic matter digestibility (ivOMD), where CP, EE and OM are in gram per kilogram DM and ivOMD values obtained from our previous in vitro study with mean values of 530 g/kg DM.

Milk samples were composited during the last 7 days of each experimental period, according to yield, for both the morning and afternoon milking, preserved with 2-bromo-2 nitropropane-1, 3-dial, and stored at 4 °C until analysis for fat, protein, lactose, totals solids, and solids-not-fat content by infrared methods using Milko-Scan 33 (Foss Electric, Hillerod, Demark).

At the end of each period, jugular blood and rumen fluid samples were collected at 0, 2 and 4 h after feeding. A blood sample (about 10 mL) was collected from the jugular vein (at the same time as rumen fluid sampling) into tubes containing 12 mg of ethylene diamine tetra-acetic acid (EDTA), and plasma was separated by centrifugation at 500 x g for 10 min and stored at -20 °C until analysis of blood urea N according to the method of Crocker (1967). Approximately 200 mL of rumen fluid was taken from the rumen by a stomach tube connected with a vacuum pump at each time at the end of each period. Rumen fluid was immediately measured for pH and temperature using (Hanna Instruments HI 8424 microcomputer, Singapore) after withdrawal. Rumen fluid samples were then filtered through 4 layers of cheesecloth. Fluid sample was taken into bottle containing 5 mL of 1 mol/LH2SO4 added to 45 mL of rumen fluid. The mixture was centrifuged at 16,000 x g for 15 min, and the supernatant was stored at -20 °C before NH3-N analysis using the Kjeltech Auto 1030 Analyzer and volatile fatty acid (VFA) analysis using high performance liquid

chromatography (HPLC). The HPLC-system consisted of a Shimadzu VP SERIES with SpD10A detector and WINCHROM software. A 3.9 mm x 300 mm stainless-steel column, packed with ReproGel H and a pre-column, packed with the same material were used. The mobile phase consisted of 10 mmol/L H2SO4 (pH 2.5) and the flow rate was 0.8 mL/min. The UV detector (at 210 nm) was employed for quantification. The UV-Visible spectra were recorded at the peak maxima and were corrected for the solvent background. The results were determined, using the standard volatile acids (Merck, India) as control. 2.3 Statistical analysis

All data from the experiment were analyzed according to a 4 x 4 Latin square design using the GLM procedure (SAS, 1998) according to the model: Yijk= m +M+ Aj+ Pk+ sijk, where Yjk, observation from cow j, receiving TMR i, in period k; m, the overall mean, M;-, effect of GCC to rice straw ratios (i = 1, 2, 3, 4), Aj, the effect of cows (j = 1, 2, 3, 4), Pk, the effect of period (k = 1, 2, 3, 4), and j residual effect. Significant differences between individual means were evaluated using the Duncan's multiple comparison tests when a significant (P < 0.05) effect was detected (Steel and Torrie, 1980). Standard errors of means were calculated from the residual mean squares in the analysis of variance. 3. Results and Discussion 3.1 Chemical composition of feeds

The TMR diets contained concentrations of 12.9% to 13.2% CP and 10.0 to 11.3 MJ/kg DM of ME, sufficient for supporting the requirement of dairy cows yielding 10 to 15 kg/d milk with 4% milk fat (NRC, 2001). These values were expected to support the level of performance of the cows in our study. Furthermore, GCC was established as high-quality roughage and RS as having poor quality when comparing the chemical composition of hemicelluloses and cellulose (Avila-Segura et al., 2011; Van Eylen et al., 2011; Liu et al., 2011). The hemicellulose content in GCC is higher than in RS at 13.02% (see Table 1), while

cellulose is lower, at 4.5% DM. Hemicellulose likely has an even higher digestion fraction than cellulose (Van Eylen et al., 2011). Lignin were ranged from 4.5% to 5.8% DM, while RS had higher lignin content than GCC. Therefore, GCC contains high hemicellulose, low in cellulose and lignin, which tends to increase digestibility and result in enhanced dry matter feed intake.

3.2 Effect on feed intake, nutrient intake and digestibility

Cows fed higher proportions of GCC (TMR1 and TMR2) consumed significantly more feed than those fed TMR3 and TMR4 (P < 0.05). Dry matter intake (DMI) is fundamentally important in nutrition because it establishes the amount of nutrients available to an animal for health and production, including milk production. The data obtained in this study showed that CP, OM and ME intakes were significantly different (P < 0.05) among the treatments, with the linearly greatest values for dairy cows fed TMR1 (Table 2). These results were in agreement with Emery et al. (1964), who showed that GCC was better roughage than ground hay and equal to chopped hay for maintaining feed intake in dairy cows. The difference in intake response is attributed to the higher-quality of the GCC ration compared to the lower-quality RS. It should be pointed out that a GCC could substitute for RS (Calabro et al., 2012; 2014). This means that if a slightly poorer RS, which would probably be the quality of RS on most dairy farms, had been used for comparison, GCC would have compared even more favorably with RS than occurred in our study. Rice straw on most dairy farms is generally of lower quality than used here (Wachirapakorn et al., 2014) and GCC could be expected to compare even more favorably than in this study. The apparent digestibility of nutrients was not altered by the GCC:RS ratio (P > 0.05). Moreover, there was a trend for digestion coefficients of DM and OM to increase as GCC proportion was increased due to the higher DM degradation of GCC as compared to RS. No significant differences existed in fiber digestibility among the rations, which was probably due to the comparable intake of fiber in

the rations (Wanapat and Kang, 2015; Wanapat et al., 2015). In addition, the digestibility values for all of the rations were lower than expected from most published values for ration components. However, the digestibilities were similar but slightly lower than those reported by Wanapat et al. (2009) and Wachirapakorn et al. (2014) in a similar experiment involving GCC. The limitation of power in the current experimental design may also affect the digestibility data considerably.

3.3 Milk production and composition

Milk yields increased (P > 0.05) with incremental ratios of GCC in TMR diets at 13% and 20% (13.1, 13.1, 12.4 and 12.4 kg/d for TMR1, TMR2, TMR3 and TMR4, respectively). Feed efficiency was similar for all diets (P > 0.05). More feed (DM, CP, OM, and ME) was consumed and milk yield was higher with the inclusion of GCC in the ration to replace RS. The kg of milk per kg of DMI and 4% FCM per kg of DMI were quite low which indicated that dietary treatments could have potential for improving milk production in cows. However, it has been debated whether milk production is driven by intake or whether intake is driven by milk production. On the basis of ME intake regulation theory and others theories, cows appear to consume feed to meet energy needs, suggesting that intake is driven by milk production (NRC, 2001; Calabro et al., 2012). Numerous lactation studies with bovine somatotropin (27 mg/d) have clearly shown this increase in ME intake in response to energy expenditure, in which DMI follows milk production (Etherton and Bauman, 1998).In addition, the ratio of GCC in the TMR had no significant negative effects (P > 0.05) on milk compositions. Milk fat content and energy corrected milk were also not affected (P > 0.05) by the increase in cobs but tended to be higher for the high GCC ration (Table 3).

3.4 Characteristics of ruminal fermentation and blood metabolites

The rumen parameters measured were pH, temperature, NH3-N, and VFA. Blood urea N (BUN) was also determined to investigate the relationship with rumen NH3-N and protein

utilization. Rumen fluid pH was not altered among the treatments, and the values were stable at pH 6.8 to 6.9. Ruminal pH ranges from 6.8 to 6.9, according to Wanapat and Cherdthong (2009), who suggested that the optimum level of pH in the rumen for microbial digestion of fiber and protein should be 6.5 to 7.0 when fed mostly on roughages. Ruminal NH3-N and BUN ranged from 13.8 to 16.4 mg/dL and 9.3 to 9.7 mg/dL, respectively (Table 4). The NH3-N and BUN values tended to be higher in cows fed the highest ratio of GCC and were in good ranges for rumen fermentation. Ruminal NH3-N is an important nutrient in supporting efficient rumen fermentation (Satter and Slyter, 1974; Cherdthong et al., 2011a, b). Ruminal NH3-N concentrations in this study ranged from 13.8 to 16.4 mg/dL, which agreed with the report of Wanapat and Pimpa (1999) (13.6 to 17.6 mg/dL).

The total VFA, acetic acid, propionic acid, butyric acid proportions, and acetic acid:propionic acid ratio are shown in Table 4. There were no significant differences in VFA concentrations or molar proportions of VFA (P > 0.05). The total VFA concentrations in all of the treatments ranged from 133.1 to 139.8 mmol/L and were similar to those reported by Wanapat et al. (2008, 2009a) also, the proportions of acetate, propionate and butyrate in this study were in accordance with Wanapat et al. (2008, 2009a). The proportions of volatile fatty acids (acetate, propionate and butyrate) were not affected by GCC, which agreed with Wanapat et al. (2009a), who found that acetate, propionate and butyrate concentrations in swamp buffaloes were not affected by GCC and urea at 15 g/kg. 4. Conclusions and recommendations

It was concluded that ground corn cobs used as the whole roughage source in TMR containing 60% concentrate significantly improve nutrient intake and milk yield in lactating dairy crossbred cows. These findings should be applied further in practical dairy feeding in the tropics to increase production efficiency. Acknowledgements

The authors would like to express our sincere thanks to the Tropical Feed Resources Research and Development Center (TROFREC), Department of Animal Science, Faculty of Agriculture, Khon Kaen University (KKU), Thailand for providing financial support for the research and the use of the research facilities. This work was also supported by the increase production efficiency and meat quality of native beef and buffalo research group, KKU. References

Association of Official Analytical Chemists (AOAC). Official methods of analysis. 17th ed.

Arlington, VA, USA: AOAC; 2000. Avila-Segura M, Barak P, Hedtcke JL, Posner JL. Nutrient and alkalinity removal by corn grain, stover and cob harvest in Upper Midwest USA. Biomass Bioenerg 2011;35:1190-95.

Calabro S, Cutrignelli MI, Gonzalez OJ, Chiofalo B, Grossi M, Tudisco R, et al. Meat quality

of buffalo young bulls fed faba bean as protein source. Meat Sci 2014;96:591-6. Calabro S, Guglielmelli A, Iannaccone F , Danieli PP, Tudisco R, Ruggiero C, et al. Fermentation kinetics of sainfoin hay with and without PEG. J Anim Physiol Anim Nutr 2012;95:842-9.

Cao Q, Xie KC, Bao WR, Shen SG. Pyrolytic behavior of waste corn cob. Bioresource Technol 2004;94:83-9.

Cherdthong A, Wanapat M, Wachirapakorn C. Influence of urea calcium mixture supplementation on ruminal fermentation characteristics of beef cattle fed on concentrates containing high levels of cassava chips and rice straw. Anim Feed Sci Technol 2011a;163:43-51. Cherdthong A, Wanapat M, Wachirapakorn C. Effects of urea-calcium mixture in concentrate containing high cassava chip on feed intake, rumen fermentation and performance of lactating dairy cows fed on rice straw. Livest Sci 2011b;136:76-84.

244 Crocker CL. Rapid determination of urea nitrogen in serum or plasma without

245 deproteinization. Am J Med Technol 1967;33:361-5.

246 Devendra C, Chantalakhana C. Animals, poor people and food insecurity: opportunities for

247 improved livelihoods through efficient natural resource management. Outl Agri 2002;

248 3:161-75.

249 Emery RS, Brown LD, Thomas JW. Comparison of corn cobs and hay in ground, restricted-

250 roughage rations affecting milk composition. J Dairy Sci 1964; 47:1322-24.

251 Etherton, TD, Bauman DE. Biology of somatotropin in growth and lactation of domestic

252 animals. Physiol Rev 1998;78:745-61.

253 Kearl LC. Nutrient Requirements of Ruminants in Developing Countries. Logan:

254 International Feedstuffs Institute. Utah State University, Utah, USA; 1982.

255 Liu H, Liu K, Yan M, Xu L, Ouyang P. gTME for improved adaptation of Saccharomyces

256 cerevisiae to corn cob acid hydrolysate. Biotechnol Appl Biochem 2011; 164:1150-59.

257 National Research Council (NRC). Nutrient requirements of dairy cattle. 7threv. National

258 Academies Press, Washington, DC, USA; 2001.

259 Robinson RH, Givens DI, Getachew G. Evaluation of NRC, UC Davis and ADAS approaches

260 to estimate the metabolizable energy values of feeds at maintenance energy intake from

261 equations utilizing chemical assays and in vitro determinations. Anim Feed Sci Technol

262 2004;114:75-90.

263 SAS. User's Guide: Statistic, Version 6, 12th Edition. SAS Inst. Inc., Cary, NC;1998.

264 Satter LD, Slyter LL. Effect of ammonia concentration on ruminal microbial protein

265 production in vitro. Br J Nutr1974;32:199-208.

266 Steel RGD, Torrie JH. Principles and Procedures of Statistics. McGraw Hill Book Co., New

267 York, NY;1980.

268 Van Eylen D, Van Dongen F, Kabel M, de Bont J. Corn fiber, cobs and stover: Enzyme-aided

269 saccharification and co-fermentation after dilute acid pretreatment. Bioresource Techno

270 2011;102:5995-6004.

271 Van Keulen J, Young BA. Evaluation of acid insoluble ash as a neutral marker in ruminant

272 digestibility studies. J Anim Sci1977;44:282-7.

273 Van Soest PJ, Robertson JB, Lewis BA. Methods for dietary fiber neutral detergent fiber, and

274 nonstarch polysaccharides in relation to animal nutrition. J Dairy Sci1991;74:3583-97.

275 Wachirapakorn C, Parmaluk P, Wanapat M, Pakdee P, Cherdthong A. Effects of levels of

276 crude protein and ground corn cobs in total mixed ration on intake, rumen fermentation

277 and milk production in crossbred Holstein Friesian lactating dairy cows. J Appl Anim

278 Res 2014;42:263-8.

279 Wanapat M, Cherdthong A. Use of real-time PCR technique in studying rumen cellulolytic

280 bacteria population as affected by level of roughage in swamp buffalo. Curr Microbiol

281 2009;58:294-9.

282 Wanapat M, Cherdthong A, Pakdee P, Wanapat S. Manipulation of rumen ecology by dietary

283 lemongrass (Cymbopogon citrates Stapf.) powder supplementation. J Anim Sci

284 2008;86:3497-503.

285 Wanapat M, Cherdthong A, Phesatcha K, Kang S. Dietary sources and their effects on animal

286 production and environmental sustainability. Anim Nutr 2015; 1:96-103.

287 Wanapat M, Kang S. Cassava chip (Manihot esculenta Crantz) as an energy source for

288 ruminant. Anim Nutr 2015;1:266-70.

289 Wanapat M, Pimpa O. Effect of ruminal NH3-N levels on ruminal fermentation, purine

290 derivatives, digestibility and rice straw intake in swamp buffaloes. Asian Australas J

291 Anim Sci 1999;12:904-7.

292 Wanapat M, Pilajun R, Kongmun P. Ruminal ecology of swamp buffalo as influenced by

293 dietary sources. Anim Feed Sci Technol 2009a;151:205-14.

294 Wanapat M, Polyorach S, Boonnop K, Mapato C, Cherdthong A. Effects of treating rice straw

295 with urea or urea and calcium hydroxide upon intake, digestibility, rumen fermentation

296 and milk yield of dairy cows. Livest Sci 2009b;125:238-43.

Table 1. Ingredients and chemical compositions of total mixed rations (TMR), ground corn

cobs (GCC) and rice straw (RS) used in the experiment (DM basis). 1_

Item TMR1 TMR2 TMR3 TMR4 RS GCC

Ingredient, %

GCC 40.0 33.0 27.0 20.0

RS 0.0 7.0 13.0 20.0

Cassava chip 17.8 17.8 17.9 18.0

Corn meal 2.4 2.4 2.4 2.4

Rice bran 4.7 4.7 4.7 4.7

Soybean meal 16.1 16.1 15.8 15.6

Whole cotton seed 7.3 7.3 7.3 7.3

Palm kernel cake 4.7 4.7 4.7 4.8

Molasses 5.0 5.0 5.0 5.0

Urea 0.4 0.4 0.4 0.5

Limestone 0.5 0.5 0.5 0.5

Dicalcium phosphate 0.5 0.5 0.5 0.5

Salt 0.3 0.3 0.3 0.3

Mineral premix 2 0.5 0.5 0.5 0.5

Chemical composition, %

Dry matter 97.1 97.0 96.7 96.7 94.6 90.5.0

Ash 6.7 7.0 7.8 8.2 8.2 2.5

Organic matter 93.3 93.0 92.2 91.7 91.8 97.5

Crud protein 13.2 13.0 12.9 12.8 3.0 2.3

Ether extract 3.2 3.2 3.3 3.2 3.4 0.8

Neutral detergent fiber 53.7 54.1 53.5 54.0 80.4 87.7

Acid detergent fiber 22.4 23.6 22.9 24.5 53.2 47.7

Hemicelluloses 3 31.9 30.5 30.6 29.6 27.2 40.0

3 Cellulose 3 16.5 19.1 17.8 18.6 41.2 36.7

Lignin 3 5.3 4.5 5.1 5.8 12.0 11.0

ME 4, MJ/kg DM 11.3 10.5 10.9 10.0 6.3 6.7

1 1 The roughage source used different ratios of GCC to RS: TMR1, 100:0; TMR2, 82.5:17.5;

2 TMR3, 67.5:32.5 and TMR4, 50:50.

3 The mineral premix per each kilogram provided vitamin A, 10,000,000 IU; vitamin E,

4 70,000 IU; vitamin D, 1,600,000 IU; Fe, 50g; Zn, 40g; Mn, 40g; Co, 0.1g; Cu, 10g; Se, 0.1g;

5 I, 0.5 g.

6 These are calculated values. Hemicellulose is NDF-ADF; Cellulose is ADF-lignin.

7 4 Metabolizable energy (ME) was calculated according to the equation described by Robinson

8 et al. (2004).

Table 2. Effect of various total mixed rations (TMR) on body weight (BW) change, dry mater intake (DMI), nutrient intake and nutrient digestibility in crossbred lactating dairy cows.1

Item TMR1 TMR2 TMR3 TMR4 SE

BW, kg 436.6 437.5 429.3 434.5 2.65

BW change, kg/d 0.5 0.6 0.4 0.2 0.19

DMI, kg/d 15.3a 15.2a 13.9b 13.4b 0.48

DMI, % BW 3.5a 3.5a 3.2b 3.2b 0.12

DMI, g/kg BW075 160.5a 158.8a 147.5b 140.9b 4.67

Digestion coefficient, %

Dry matter 73.4 72.4 68.0 65.6 3.44

Organic matter 75.5 74.3 69.8 68.8 3.44

Crude protein 82.9 81.5 80.5 76.4 3.32

Neutral detergent fiber 63.7 63.4 58.2 58.1 5.14

Acid detergent fiber 52.4 52.6 45.6 44.5 4.70

Nutrient intake, kg/d

Crude protein 2.1a 2.0a 1.8ab 1.7b 0.08

DOM 2 10.9a 10.5a 9.0ab 8.5b 0.81

Neutral detergent fiber 8.2 8.2 7.4 7.1 0.30

Acid detergent fiber 3.4 3.6 3.2 3.4 0.09

ME, MJ/d 169.5a 166.5a 136.8b 128.4b 7.11

ME, MJ/kg DM 11.3 10.9 10.0 10.0 1.23

9 SE = standard error of means; DOM = digestible of organic matter; ME = metabolizable

10 energy.

11 a,b Within a same row, means with different superscripts differ (P < 0.05)

12 1 The roughage source used different ratios of ground corn cobs (GCC) to rice straw (RS):

13 TMR1, 100:0; TMR2, 82.5:17.5; TMR3, 67.25:32.75 and TMR4, 50:50.

14 2 One kg DOM, 15.9 MJ ME/kg (Kearl, 1982).

Table 3. Effect of various total mixed rations (TMR) on milk yield and composition in crossbred lactating dairy cows.1_

Item TMR1 TMR2 TMR3 TMR4 SE

Milk yield, kg/d 13.1a 13.1a 12.4b 12.4b 0.25

4% FCM, kg/d 13.2 13.5 12.4 12.5 0.36

Protein, kg/d 0.4 0.4 0.4 0.4 0.01

Fat, kg/d 0.5 0.6 0.5 0.5 0.01

Efficiency

Milk:DMI, kg/kg 0.9 0.9 0.9 0.9 0.09

4% FCM:DMI, kg/kg 0.9 0.9 0.9 0.9 0.07

ECM milk3, kg 13.5 13.7 12.7 13.1 1.26

Milk composition, %

Fat 4.1 4.2 4.0 4.0 0.09

Protein 3.4 3.5 3.4 3.4 0.07

Lactose 4.6 4.7 4.7 4.8 0.06

Solids not fat 8.7 8.8 8.8 8.9 0.09

Total solids 12.9 13.0 12.9 ( 12.9 0.19

15 SE = standard error of means; FCM = fat-corrected milk; DMI = dry mater intake; ECM =

16 energy-corrected milk.

17 a,b Within a same row, means with different superscripts differ (P < 0.05).

18 1 The roughage source used different ratios of ground corn cobs (GCC) to rice straw (RS):

19 TMR1, 100:0; TMR2, 82.5:17.5; TMR3, 67.25:32.75 and TMR4, 50:50.

20 2 Energy-corrected milk = Milk production x (0.383 x % fat + 0.242 x % protein +

21 0.7832)/3.1138 .

Table 4. Ruminal pH, temperature, concentrations of ammonia-nitrogen (NH3-N) and volatile fatty acid (VFA) and concentration of blood urea N by feeding various diets to crossbred lactating dairy cows.1_

Item TMR1 TMR2 TMR3 TMR4 SE

Ruminal pH 6.8 6.9 6.9 6.8 0.07

Ruminal temperature, °C 38.9 39.0 39.0 38.9 0.11

Ruminal NH3-N, mg/dL 16.4 14.8 15.6 13.8 1.03

BUN, mg/dL 9.7 9.2 9.5 9.3 0.91

Total VFA, mmol/L 137.3 133.1 139.8 134.6 1.48

VFA, mol/100 mol

Acetic acid (C2) 65.6 64.1 64.5 65.2 0.22

Propionic acid (C3) 27.2 27.5 27.2 26.5 0.21

Butyric acid (C4) 8.2 8.4 8.0 8.3 0.09

C2:C3 ratio 2.4 2.3 2.4 2.5 * 0.03

22 BUN = blood urea-nitrogen; TMR = total mixed ration; SE = standard error of means.

23 a,b Within a same row, means with different superscripts differ (P<0.05);.

24 1 The roughage source used different ratios ground corn cobs (GCC) to rice straw (RS):

25 TMR1, 100:0; TMR2, 82.5:17.5; TMR3, 67.25:32.75 and TMR4, 50:50.