Effect of tannins and monensin on feeding behaviour, feed intake, digestive parameters and microbial efficiency of nellore cows

Figures & data

Table 1. Proportions of ingredients and estimated chemical composition of experimental diets.

Ingredients (% DM)	Tannin level
	0.00%	0.75%	1.50%	2.25%
Corn silage	50.00	50.00	50.00	50.00
Dry ground corn grain	32.36	32.36	32.36	32.36
Soybean meal	12.40	12.40	12.40	12.40
White salt	0.50	0.50	0.50	0.50
Mineral mixture^a	2.00	2.00	2.00	2.00
Tannin extract^b	–	0.91	1.82	2.74
Caulin	2.74	1.82	0.91	–
Chemical composition of the diet for all tannin levels
DM^c (%)		60.35
CP^c (%DM)		14.43
RDP^d (%CP)		65.30
RUP^d (%CP)		34.70
NDF^c (%DM)		28.06
NDFe^d (%DM)		24.47
ADF^c (%DM)		15.41
NFC^c (%DM)		47.59
Starch^d (%DM)		42.58
Ash^c (%DM)		6.73
Ca^c (%DM)		0.69
P^c (%DM)		0.40
EE^c (%DM)		3.19
TDN^d (%DM)		74.10
EL^d (Mcal/kg DM)		1.50

DM: Dry matter; CP: Crude protein; RDP: Ruminally degraded protein; RUP: Ruminally undegraded rotein; NDF: Neutral detergent fibre; NDFe: Effective neutral detergent fibre; ADF: Acid detergent fibre; NFC: Non-fibre carbohydrates; Ca: Calcium; P: Phosphorus; EE: Ether extract; TDN: Total digestible nutrients; E_L: Net energy for lactation.

^aMineral mixture, quantity per kg of product: 140 g of calcium, 80 g of phosphorus, 10 g of sulphur, 129 g of sodium, 80 mg of cobalt, 1400 mg of copper, 800 mg of fluorine, 80 mg of iodine, 1 g of manganese, 20 mg of selenium, 3.50 g of zinc.

^bExtract of Acacia mearnsii with 82.30% of total tannins, of which 32.30% condensed tannins.

^cDetermined through chemical analysis.

^dEstimated by the Spartan Dairy Ration Evaluator/Balancer software, version 3.0.3.

Table 2. Feeding behaviour of Nellore cows fed monensin (ppm) and tannins of A. mearnsii.

Variables	Monensin (M)		Tannin Level (TL)				SEM	p-Value
	0	30	0%	0.75%	1.5%	2.25%		M	TL	M*TL
Ruminating
NE	13.75	14.06	13.38	13.25	13.88	15.13	0.50	NS	0.0242^L	NS
TRT (min)	427.7	391.3	408.8	406.3	406.3	416.3	14.3	NS	NS	NS
NDF (min/kg)	171.2	150.7	153.3	157.6	157.0	175.9	0.04	NS	0.0059^L	NS
Eating
NE (meals)	8.31	9.06	8.50	8.00	8.63	9.63	0.42	NS	NS	NS
TET (min)	182.2	211.3	192.5	178.8	201.9	215.0	8.18	NS	0.0263^L	NS
NDF (min/kg)	73.00	82.05	72.49	69.48	78.44	89.70	3.53	NS	0.0386^Q	NS
Masticating
NE	22.06	23.13	21.88	21.25	22.50	24.75	0.66	NS	0.0247^L	NS
TMT (min)	610.3	602.5	601.3	585.0	608.1	631.3	16.1	NS	NS	NS
NDF (min/kg)	244.2	232.8	225.8	227.1	235.4	265.6	7.16	NS	0.0384^Q	NS

SEM: Standard error of mean; M: Monensin; TL: Tannin level; M*TL: Interaction between monensin and tannins; L: Linear; Q: Quadratic; NS: Non-significant.NE: Number of events; TRT: Total ruminating time; TET: Total eating time; TMT: Total masticating time; NDF: Neutral detergent fibre.

Table 3. Feed intake and total apparent digestibility of DM and its fractions of Nellore cows fed monensin (ppm) and tannins of A. mearnsii.

	Monensin (M)		Tannin Level (TL)					p-value
Variables	0	30	0.0%	0.75%	1.5%	2.25%	SEM	M	TL	M*TL
DM intake (kg/d)	9.34	9.49	9.80	9.59	9.56	8.71	0.275	NS	0.0034^L	NS
Water intake
Litres/d	31.67	24.00	29.25	28.58	27.75	25.75	1.596	NS	0.0120^L	NS
Litres /kg DM	3.31	2.54	2.99	2.96	2.84	2.93	0.111	0.0533	NS	NS
Digestibility (%)
DM	68.21	70.96	72.29	70.92	69.02	66.12	0.862	NS	<.0001^L	NS
CP	65.10	69.07	72.97	69.02	65.41	60.93	1.100	0.0387	0.0010^L	NS
NDF	56.24	55.93	61.78	58.78	56.77	47.02	1.655	NS	0.0199^Q	NS
ADF	41.12	42.64	54.91	46.84	43.85	21.91	3.032	NS	0.0336^Q	NS
EE	73.84	74.00	73.96	73.66	74.96	73.10	1.433	NS	NS	NS
NFC	81.40	85.67	85.96	84.71	81.57	81.88	0.819	0.0534	0.0063^L	NS
OM	71.03	73.73	76.24	74.09	71.36	67.82	0.928	NS	<.0001^L	NS
TDN	69.24	71.76	74.10	72.08	69.59	66.22	0.897	NS	<.0001^L	NS

SEM: Standard error of mean; M: Monensin; TL: Tannin level; M*TL: Interaction between monensin and tannins; L: Linear; Q: Quadratic; NS: Non-significant; DM: Dry matter; CP: Crude protein; NDF: Neutral detergent fibre; ADF: Acid detergent fibre; EE: Etheric extract; NFC: Non-fibrous carbohydrates; OM: Organic matter; TDN: Total digestible nutrients.

Table 4. Degradability of DM, NDF and CP of Nellore cows fed monensin (ppm) and tannins of A. mearnsii.

	Monensin (M)		Tannin Level (TL)				SEM	p-value
Variables	0	30	0.00%	0.75%	1.50%	2.25%		M	TL	M*TL
DM
a (%)	32.84	32.53	32.39	32.87	32.41	33.08	0.155	NS	NS	NS
b (%)	53.29	52.90	55.15	52.77	52.79	51.65	0.500	NS	0.0183^L	NS
c (h^–1)	0.043	0.043	0.051	0.046	0.041	0.035	0.002	NS	0.0010^L	NS
RED (%)	62.67	61.65	64.00	62.25	61.37	61.03	0.761	NS	0.0816^L	NS
PD (%)	86.13	85.58	87.54	85.64	85.52	84.73	0.409	NS	0.0268^L	NS
Und (%)	13.87	14.42	12.46	14.36	14.48	15.27	0.409	NS	0.0268^L	NS
NDF
b (%)	65.12	65.05	69.75	66.99	62.93	60.67	1.092	NS	0.0008^L	NS
c (h^–1)	0.030	0.026	0.034	0.025	0.028	0.023	0.002	NS	0.0399^L	NS
lag (h)	2.64	3.63	2.59	2.95	2.96	4.04	0.288	NS	0.0301^L	NS
RED (%)	27.14	25.17	31.64	24.98	24.88	23.12	1.411	NS	0.0087^L	NS
PD (%)	65.12	65.05	69.95	66.99	62.93	60.67	1.092	NS	0.0008^L	NS
Und (%)	34.88	34.95	30.25	33.02	37.07	39.33	1.092	NS	0.0008^L	NS
CP
a (%)	33.83	34.52	32.83	34.94	34.05	34.87	0.498	NS	NS	NS
b (%)	60.29	60.54	63.90	59.95	58.74	59.07	0.741	NS	0.0208^L	NS
c (h^–1)	0.042	0.039	0.046	0.045	0.041	0.032	0.002	NS	0.0114^L	NS
RED (%)	66.89	65.97	67.93	67.57	66.07	64.16	0.913	NS	NS	NS
PD (%)	94.12	94.99	96.74	94.89	92.80	93.79	0.517	NS	0.0095^L	NS
Und (%)	5.88	5.007	3.26	5.11	7.20	6.21	0.517	NS	0.0095^L	NS

SEM: Standard error of mean; M: Monensin; TL: Tannin level; M*TL: Interaction between monensin and tannins; L: Linear; NS: Non-significant; a: Water-soluble and completely degradable fraction of the analysed nutritive component leaving the nylon bag rapidly; b: Potentially degradable fraction; c: Rate of degradation of b; lag: time at which the equation derived for a data set equals the actual potentially degradable fraction at zero time; RED: Real effective degradability; PD: Potential degradability (a + b); Und: Undigested fraction (100-PD).

Table 5. Rumen kinetic of Nellore cows fed monensin (ppm) and tannins of A. mearnsii.

	Monensin (M)		Tannin Level (TL)				SEM	p-value
Variables	0	30	0%	0.75%	1.5%	2.25%		M	TL	M*TL
Rumen DM (%)	12.92	13.49	12.92	13.04	13.46	13.40	0.211	NS	NS	NS
Rumen liquid mass (kg)	35.69	34.94	33.34	34.77	36.89	36.26	0.979	NS	0.0085^L	NS
Rumen solid mass (kg)	5.36	5.45	5.01	5.23	5.72	5.67	0.203	NS	0.0117^L	NS
Total rumen mass (kg)	41.05	40.39	38.34	40.00	42.61	41.93	1.164	NS	0.0072^L	NS
kt (%/h)	7.69	7.45	8.65	7.84	7.10	6.684	0.235	NS	0.0001^L	NS
kp (%/h)	3.45	3.50	3.82	3.73	3.38	2.99	0.153	NS	0.0122^L	NS
kd (%/h)	4.24	3.94	4.84	4.11	3.72	3.70	0.226	NS	0.0316^L	NS

SEM: Standard error of mean; M: Monensin; TL: Tannin level; M*TL: Interaction between monensin and tannins; L: Linear; NS: Non-significant; kt: Disappearance rate of rumen solid mass (kp + kd); kd: Rate of digestion in the rumen (kt – kp); kp: Passage rate of undigested residues (kt – kd).

Table 6. Urinary parameters, synthesis and efficiency of microbial protein synthesis of Nellore cows fed monensin (ppm) and tannins of A. mearnsii.

	Monensin (M)		Tannin Level (TL)					p-value
Variables	0	30	0.0%	0.75%	1.50%	2.25%	SEM	M	TL	M*TL
Urinary volume
Litres/d	10.7	7.54	9.38	9.50	9.19	8.32	0.578	NS	NS	NS
Urinary compounds
Urea (g/d)	137.2	138.3	154.7	143.7	132.9	119.6	9.258	NS	0.0051^L	NS
Al (mmol/d)	127.3	129.0	130.7	130.1	126.7	125.1	4.149	NS	NS	NS
UA (mmol/d)	19.38	20.45	22.00	19.59	20.15	17.92	1.200	NS	0.0092^L	NS
PuD (mmol/d)	146.6	149.6	152.7	149.9	146.7	143.0	4.608	NS	NS	NS
Synthesis of micN
g/d	83.91	86.81	89.08	86.92	84.00	81.44	3.878	NS	NS	NS
EMNS (g/kg DOM)	14.86	14.10	13.94	13.71	14.02	16.25	0.687	NS	NS	NS

SEM: Standard error of mean; M: Monensin; TL: Tannin level; M*TL: Interaction between monensin and tannins; L: Linear; NS: Non-significant; Al: Allantoin; UA: Uric acid; PuD: Purine derivatives; micN: Microbial nitrogen; EMNS: Efficiency of microbial nitrogen synthesis; DOM: Digested organic matter.

Table 7. Nitrogen balance of Nellore cows fed monensin (ppm) and tannins of A. mearnsii.

Variables	Monensin (M)		Tannin Level (TL)				SEM	p-value
	0	30	0.0%	0.75%	1.5%	2.25%		M	TL	M*TL
N ingested (g/d)	205.7	209.9	217.1	211.7	211.5	190.8	6.260	NS	0.0043^L	NS
N excreted (g/d)
Faeces	68.60	62.36	55.99	62.85	70.85	72.23	2.328	NS	<.0001^L	NS
Urine	63.91	64.45	72.10	66.96	61.94	55.74	4.314	NS	0.0051^L	NS
N retained (g/d)	73.17	83.09	89.00	81.88	78.69	62.95	5.683	NS	0.0027^L	NS
N balance (% of N ingested)
Faeces	33.86	30.03	26.26	30.08	33.54	37.90	1.065	0.0390	<.0001^L	0.0828
Urine	31.58	30.43	34.58	31.26	29.04	29.12	1.960	NS	0.0276^L	NS
Retained	34.57	39.54	39.15	38.66	37.42	32.98	2.201	NS	0.0228^L	NS

SEM: Standard error of mean; M: Monensin; TL: Tannin level; M*TL: Interaction between monensin and tannins; L: Linear; NS: Non-significant; N: Nitrogen; N retained: N ingested – N excreted (faeces + urine).