Nutrient digestibility and rumen fermentation of Thai native purebred compared with Thai native x Lowline Angus crossbred beef cattle

ABSTRACT

The aim of this study was to compare voluntary feed intake, nutrient digestibility, and rumen fermentation of Thai native and Thai native x Lowline Angus crossbred beef cattle fed with different diets. Three different diets consisting of ad libitum rice straw (RS), ad libitum RS supplemented with 0.5% body weight (BW) concentrate (RS+C), and ad libitum Pangola grass hay (PH). The experiment was conducted as 3 × 3 replicated Latin square design with a factorial arrangement of dietary treatment and breed. It was found that Thai native and Thai native x Lowline Angus crossbred beef cattle had comparable roughage intake, BW change, nutrient digestibility, and all parameters from rumen fluid. Cattle fed with different type of feed showed similar roughage intake, BW change, and number of protozoa and fungal zoospore in rumen fluid. However, nutrient intake and digestibility of cattle supplemented with concentrate were higher than those fed the roughage alone. Accordingly, concentration of total volatile fatty acid and proportion of propionic acid in rumen fluid of cattle received concentrate was higher than cattle fed only RS (P < .05) but not for cattle fed with PH. Moreover, the PH-fed group had a higher ammonia concentration in rumen fluid than did the RS-fed group (P < .05). Therefore, the two breeds of beef cattle showed comparable feed response while supplementation of concentrate at 0.50% BW was a useful alternative feeding pattern.

KEYWORDS:

• Thai native cattle
• Lowline Angus
• intake
• digestibility
• rumen fermentation

1. Introduction

Beef cattle production has been identified as one of several main sectors in Thai agriculture. In 2011, there were about 6.6 million head of beef cattle in Thailand and two from three are native and native crossbred (71.0%); besides, 34.4% of those are positioned in the North East region (DLD of Thailand 2011). Thai indigenous cattle belong to the Bos indicus genus similar to Indian cattle. They are suited to Thai raising conditions, due to their heat tolerance, insect and disease tolerance, superior reproductive performance, and the merit of efficient utilization of low-quality roughage. However, carcass percentage and growth rate of native beef were inferior to crossbred beef (Opatpatanakit & Sethakul 2010). Moreover, Sethakul et al. (2008) reported that native beef meat had higher lean percentage and tenderness with lower fat percentage than crossbred beef meat. Therefore, native beef might be advantageous for healthy meat production or natural beef as suggested by Duanyai et al. (2009).

There are a number of crossbred beef strains in Thailand such as Brahman crossbred, KU beef, Tak beef, Kabinburi beef, Thai black, and other 50% European crossbreds. Thai native x Lowline Angus crossbred (50:50) is another beef cattle type which was developed by Sawasdipan (2003) in 2003. It has small size and is heat-tolerant like native beef with a high growth rate like Lowline Angus. However, efficiency of feed utilization, rumen fermentation, and carcass characteristics still need more investigation. Many studies found that crossbred beef cattle had growth performance greater than those indigenous cattle. Wongsri et al. (1998) reported that native beef cattle had average daily gain lower than Brahman crossbred beef which agreed with Van Zyl (1990) who found comparable results in South Africa. In addition, improved weaning weight, final body weight (BW), and average daily gain were achievable from Charolais x Hereford crossbred when compared with their purebred (Kamieniecki et al. 2009). Therefore, this study was to investigate feed intake, nutrient digestibility, and rumen fermentation of Thai indigenous beef and Lowline Angus crossbred beef cattle when fed with different feeds.

2. Materials and methods

2.1. Animals and feeds

Six beef animals, three 1-year old of Thai native (TN), and three of Thai native x Lowline Angus crossbred beef cattle (TAC, 50:50) with a BW of 120 ± 10 kg were randomly assigned to receive three dietary treatments according to a 3 × 3 replicated Latin Square design, with a factorial arrangement of dietary treatment and breed. Three different diets consisting of ad libitum rice straw (RS), ad libitum RS supplemented with 0.5% BW concentrate (RS + C), and ad libitum Pangola grass hay (PH). Concentrate was composed of ground corn, rice bran, soybean meal, palm kernel meal, molasses, salt, and mineral mixed for beef cattle at 65.0%, 12.5%, 11.0%, 8.0%, 2.0%, 0.5%, and 1.0% dry matter (DM), respectively. Chemical composition of experimental diets is presented in Table 1. The experiment was conducted for 3 periods, and each period lasted 21 days. All cattle were raised in individual pens, and fed with their respective treatment split between two equal daily feeds (07.00 and 16.00). Fresh water was available ad libitum for all animals, which were housed in individual pens.

Table 1. Chemical composition (% of DM) of experimental feeds.

Feed		Nutrient
	DM	OM	CP	EE	NDF	ADF	NFC
Concentrate	87.0	95.0	11.0	3.2	15.0	7.0	65.8
RS	78.4	90.5	2.5	0.6	67.0	44.9	20.4
PH	78.3	94.2	7.0	1.3	70.1	35.9	15.9

Note: DM = dry matter, OM = organic matter, CP = crude protein, EE = ether extract, NDF = neutral detergent fibre, ADF = acid detergent fibre, NFC = non-fibre carbohydrate.

2.2. Samples and analysis

Individual animal BW was determined before and at the end of each period. Measurements of feed intake and samples of feeds, refusals, faeces, rumen fluid, and blood were made during the 21 days of each period. Faeces sample of each animal was collected once a day during the last five days of each period by grab sampling while rumen fluid sample was collected by using stomach tube with vacuum pump on the last day of each period. The samples were stored at –20°C before analysis. Daily faeces collected in each period were bulked, mixed and a 0.5% sub-sample taken for later analysis.

Feed and faecal samples were dried in a forced-air oven at 60°C for 96 h, ground through a 1-mm stainless steel screen (Cyclotec 1093 Sample mill, Tecator, Hoganas, Sweden), and analysed according to the Association of Official Analytical Chemists (AOAC 1995) for DM (method 967.03), ether extract (EE, method 920.39) and ash (method 942.05). Total nitrogen in samples of feeds and faeces was determined according to AOAC (1991) (method 984.13). The method of Van Soest et al. (1991) was used to determine neutral detergent fibre (NDF) and acid detergent fibre (ADF) on a ash-free basis. Non-fibre carbohydrate (NFC) in feed was calculated by subtracting ash, crude protein (CP), EE, and NDF proportions from DM. Acid insoluble ash was used as the internal marker for calculation of apparent nutrient digestibility as modified by Van Keulen and Young (1977). Rumen fluid analyses for ammonia nitrogen (NH₃-N) by the method of Bremner and Keeney (1965). Volatile fatty acids (VFA) were analysed using High Pressure Liquid Chromatography (Instruments by controller water model 600E; water model 484 UV detector; column novapak C18; column size 3.9 mm ×  300 mm; mobile phase 10 mM H₂PO₄ [pH 2.5]) according to Samuel et al. (1997). Rumen fluid was collected for direct count of protozoa and fungal zoospores using the methods of Galyean (1989) by a haemocytometer. Protozoan population may respond to non-structural carbohydrate such as soluble sugar and starch, while fungi may be affected by the level of dietary fibre.

2.3. Statistical analysis

All data were statistically analysed according to a 3 × 3 Replicated Latin Square design using the general linear model procedure of SAS (1996). Data were analysed according to the experimental design using the model Y_ijkh = μ + B_i + A_j(i) + T_k + P_h + ε_ijkh, where Y_ijkh is the observation from replicate or breed i, animal j, receiving diet k, in period h; μ, the overall mean; B_i, effect of breed (i = 1–2); A_j(i), the effect of animal within breed (j = 1–3); T_k, the effect of diet (k = 1–3); P_h, the effect of period (h = 1–3); and ε_ijkh, the random residual error. Differences between dietary treatment means were determined by Duncan's New Multiple Range Test (Steel & Torrie 1980). Differences between means with P < .05 were accepted as representing statistically significant differences. The interaction between T and B effects was previously tested for all the dependent variables. Because the interaction was not statistically significant (P > .05), it was removed from the model.

3. Results and discussion

Voluntary roughage intake and BW change were similar among TN and TAC beef cattle (Table 2). The Working Committee of Thai Feeding Standard for Ruminant (TFSR 2008) and National Research Council (NRC 2000) reported that roughage intake of beef cattle is between 1.3% and 2.0% of BW according to the quality. The average roughage intake (RS and PH) registered in this study was 1.63% of BW. Type of feed did not affect roughage intake and BW change of animal, although roughage intake of concentrate supplementation group trended to be higher than the other two groups. These could indicate that the difference in quality of feed did not impact intake and utilization by native beef cattle. However, Wanapat (1999) mentioned that high-quality feed is able to supply adequate nutrients for rumen microorganism, leading to more digestibility, and then increasing of intake. The BW loss of experimental cattle showed that energy allowances of the diets were not adequate to cover the maintenance energy requirements. Thus, just roughage or concentrate supplementation at 0.50% of BW was not sufficient for beef cattle during growing stage. TFSR (2008) suggested that one-year, Thai native or Thai native crossbred beef cattle require 2.9 mega june (MJ) of metabolisable energy (ME) and 180 g of CP for maintenance. Moreover, due to experimental animals being selected from a herd to fit in individual pens, animals may suffer stress with effects on intake and growth.

Table 2. Voluntary roughage intake and apparent nutrient digestibility of the diets (%).

Nutrient	Breed^A			SEM	Diet^B				SEM
	TN	TAC	P-value		RS	RS+C	PH	P-value
Roughage intake
kg/d	2.10	2.18	0.10	0.04	2.10	2.20	2.12	0.06	0.05
% BW	1.66	1.61	0.56	0.04	1.60	1.70	1.61	0.14	0.04
Apparent digestibility, %
DM	62.7	62.2	0.18	0.69	53.2^c	65.6^a	66.5^a	<0.01	0.49
OM	59.6	61.0	0.19	0.83	55.1^b	67.8^a	67.7^a	<0.01	1.02
CP	27.3	24.8	0.70	2.42	23.7^b	28.4^a	27.4^a	<0.01	1.91
NDF	62.0	63.5	0.24	1.43	60.8^b	67.4^a	60.0^b	0.03	1.75
ADF	51.7	53.3	0.20	1.39	54.6^a	58.6^a	44.3^b	<0.01	1.71

Note: SEM = standard error of sample mean. DM = dry matter, OM = organic matter, CP = crude protein, NDF = neutral detergent fibre, ADF = acid detergent fibre.

^ATN = Thai native, TAC = Thai native x Lowline Angus crossbred (50:50).

^BRS = rice straw, RS+C = rice straw plus concentrate, PH = Pangola grass hay.

^a,b,cValues on the same row with different superscripts differed (P < .05).

The average nutrient digestibility registered in the experiment was 65.5%, 60.2%, 26.01%, 62.7%, and 52.5% for DM, OM, CP, NDF, and ADF, respectively. These are consistent with Gunun et al. (2013), who reported the digestibility by dairy steers fed with RS and 0.50% BW concentrate were 56.7%, 61.7%, 55.8%, and 51.3% for DM, OM, NDF, and ADF, respectively; however, digestibility of CP was 50.9%. Moreover, digestibilities in PH were 63.2 ± 9.5, 64.6 ± 7.1, 56.8 ± 14.5, 68.2 ± 7.6, and 62.0 ± 8.4% for DM, OM, CP, NDF, and ADF, respectively (Tikam et al. 2013). Low digestion of CP of RS (23.7%) and PH (27.4%) in this study was possibly caused by uniting of protein and fibre. Jung (1997) suggested that highly lignifications in cell wall of tropical plants may bind nitrogen and possibly disrupt digestion by microbial enzyme. The lack of differences between the two breeds, in terms of digestibility, indicated that Thai native x Lowline Angus crossbred beef cattle are able to utilize tropical feed comparable to purebred Thai native beef cattle. This agrees with Beaver et al. (1989) who found that Brangus (Brahman x Angus crossbred) had similar voluntary dry matter intake (DMI) and digestibility when compared with Angus purebred.

Cattle receiving PH had lower digestibility of NDF, and ADF when compared with concentrate supplementation group (P < .05). These results are in agreement with Vallimont et al. (2004) who reported that sucrose (non-fibre carbohydrate) supplementation increased apparent digestibility of NDF and ADF. The reduction in fibre digestibility in these latter studies may be due to the NFC-fermenting bacteria competing with the fibre-digesting bacteria for available N (Stokes et al. 1991; Brooks et al. 2012). Russell (2002) concluded that providing sufficient degradable carbohydrate and protein in the rumen will enhance digestion of feed by microorganism. Furthermore, decrease in fibre digestion can be attributed to a decrease in pH, or a ‘carbohydrate effect’ (Mould et al. 1984). The carbohydrate effect refers to a preference by ruminal microorganisms for more readily available carbohydrates. In addition, cattle receiving only RS was lower in CP digestibility than those cattle in other feeds (P < .05). High content of silica and lignifications in cell wall of RS and hay could be the reason for low protein digestion.

Concentrations of ammonia and VFA, and populations of protozoa and fungal zoospores were similar among TN and TAC (Table 3). Because daily dietary intake was similar among breeds of beef cattle, this could be the explanation why fermentation and microbial population in the rumen of Thai native and Thai native x Lowline Angus crossbred beef cattle were comparable. However, cattle fed with PH showed higher ammonia concentration in rumen fluid than cattle fed with RS (P < .05) but were not different compared with cattle receiving concentrate supplementation. Concentration of total VFA and proportion of propionic acid in rumen fluid of concentrate supplementation group were higher than the rice-straw-fed group (P < .05) but were similar with the PH-fed group. In contrast, proportion of acetic acid in rumen fluid of cattle fed only RS was significantly higher than cattle receiving concentrate supplementation (P < .05) but was not different from cattle fed PH. In addition, type of diet did not affect proportion of butyric acid and population of microbes in the rumen of beef cattle.

Table 3. Ammonia and VFA concentrations, and microbial populations in the rumen of beef cattle.

Item	Breed^A			SEM	Diet^B				SEM
	TA	TAC	P-value		RS	RS+C	PH	P-value
Ammonia-nitrogen, mg%	15.0	15.4	0.73	0.89	12.7^b	15.6^ab	18.2^a	0.05	1.09
Total VFA (TVFA), mmol/L	78.2	79.5	0.59	3.07	71.6^b	87.7^a	77.3^ab	<0.01	3.21
Acetic acid, % TVFA	71.4	68.5	0.75	2.73	74.5^a	65.3^b	70.0^ab	0.02	2.85
Propionic acid, % TVFA	20.4	22.7	0.42	2.11	18.2^b	26.3^a	20.2^ab	0.04	2.22
Butyric acid, % TVFA	8.2	8.8	0.56	1.45	7.3	8.4	9.8	0.17	1.54
Protozoa, log cell/mL	4.79	4.74	0.80	0.12	4.67	4.78	4.85	0.69	0.15
Fungal zoospore, log cell/mL	5.52	5.72	0.19	0.10	5.40	5.70	5.77	0.13	0.12

Note: ^ATN = Thai native, TAC = Thai native x Lowline Angus crossbred (50:50). SEM = standard error of sample mean.

^BRS = rice straw, RS+C = rice straw plus concentrate, PH = Pangola grass hay.

^a,bValues on the same row with different superscripts differed (P < .05).

Higher ammonia concentration in the rumen of the Pangola-fed group could be due to higher CP intake compared with the rice-straw-fed group, and greater continuous protein provision compared with concentrate supplementation group. This may explain the ingested CP was 52.5, 126.2, and 148.4 g/d for beef fed only RS, RS with concentrate supplementation, and PH, respectively. Supplementation of diet that contains high proportion of NFC possibly led to an increase in VFA production. Penner et al. (2009) illustrated that production of VFA especially propionic acid can be induced by concentrate supplementation. Dehority (2003) also stated that supplying of NFC is able to stimulate VFA synthesis particularly propionic acid. However, it is difficult to alter butyric acid proportion due to the complexity of synthesis. Although rumen fermentation end-products were changed by type of diet, population of protozoa and fungi did not change. However, the major group of microorganism that digests feed in the rumen is bacteria not protozoa or fungi (Russell & Rychlik 2001). Thus, determination of bacteria population in the rumen should be further studied.

4. Conclusion

Thai native purebred and Thai native x Lowline Angus crossbred beef cattle showed a similar response to different diets. However, this study used diets with a very low energy concentration that were not appropriate for the requirements of growing beef cattle. Therefore, new explorations regarding TAC breeds should be performed with diets able to support growing these beef cattle, in order to find solutions useful for practice.

Acknowledgements

Research facilities provided by Office of Laboratory and Farming, Faculty of Agriculture, Ubon Ratchathani University are gratefully acknowledged.

Disclosure statement

No potential conflict of interest was reported by the authors.

Funding

The authors are grateful for the financial support of research from the Office of Academic and Research Promoter, Ubon Ratchathani University, Thailand.