ANIMAL SCIENCE

Ruminal degradability of supplements based on three native forages and adapted to the Colombian Amazonian piedmont

A. R. Riascos Vallejos^{1  *} 
http://orcid.org/0000-0001-6627-9372

J. J. Reyes González² 
http://orcid.org/0000-0002-9681-1187

D. Valenciaga Gutiérrez¹ 
http://orcid.org/0000-0002-4681-4814

J.E. Apráez Guerrero³ 
http://orcid.org/0000-0002-8161-8229

¹Instituto de Ciencia Animal, Apartado Postal 24, San José de las Lajas, Mayabeque, Cuba. Servicio Nacional de Aprendizaje - SENA, Regional Putumayo.

²Instituto de Investigación Pastos y Forrajes. Ministerio de la Agricultura. Av. Independencia km 81/2. Boyeros, La Habana, Cuba.

³Universidad de Nariño, San Juan de Pasto, Colombia.

Resumen

In order to evaluate the in situ ruminal degradability of different supplements based on native forages and adapted to the Amazonian piedmont, three sheep with ruminal cannula were used. The evaluated treatments were: T1Control, T2 and T3 (0.5 kg concentrate + supplement with 20 and 40 % of Trichantera gigantea inclusion, respectively), T4 and T5 (0.5 kg concentrate + supplement with 20 and 40 % de Piptocoma discolor inclusion) and T6 and T7 (0.5 kg concentrate + supplement with 20 and 40 % Hibiscus rosa-sinensis inclusion). Analysis of variance according to completely random design with factorial arrangement (3x2) was carried out. The treatments with 20% of H. rosa-siensis inclusion reached an in situ ruminal degradability of DM and OM at 72 incubation hours higher than 84.65 and 72.79 %, respectively. The lower ruminal degradability of DM and OM at 72 incubation hours was for the treatment with T. gigantea at 40%, followed by the treatment with P. discolors at 40 %. The treatments with H. rosa-siensis at 20 % and T. gigantea at 20 % showed the highest effective degradation for DM and OM, respectively. The in situ degradability of DM, OM, NDF and ADF showed the highest values in the H. rosa-sinesis and P. discolor species, without differences between them, respect to T. gigantea. The inclusion of 20% of forages in the supplement is a viable option from the nutritional supply point of view in supplementation programs.

Key words: Piptocoma discolor; supplementation; Amazonia; Putumayo

In accordance to the Monitoring System of Rainforests and Carbon (MSR and C), for 2016 the deforestation in Colombia reached the 178.597 ha. However, this one had been concentrated in seven nucleus around the country, where the most important is the Amazonia which includes Putumayo, Caquetá, Guaviare and Meta departments with 34 % of the national deforestation rate (^{Alayón et al. 2018}).The main cause of trees cutting in the region is to fit out meadows for cattle livestock, as a way to increase lands value (^{IDEAM 2017}).It is estimate that the 19 % of the sowing meadows in the Colombian Amazonian, after deforestation process, are currently without use (^{Blanco-Wells and Günther 2019}).This region had showed a transformation in the productive activity, which had been passed to the crops sowing from illicit use to the increase in the agricultural world, guiding now mainly to livestock.

If deforestation in Putumayo department is attributed to a complex net of activities, it is possible to identify that the most common stock in the most part of agricultural frontier, begins with the deforestation to establish seasonal cultures for two or three years, and later sowing this areas with grasses which after one or two years are used specially for agricultural production, for being productive systems of extensive livestock (^{Sotelo et al. 2017}).

The variations in the intensity and frequency of rainfalls, El Niño phenomenon and high temperatures, are having important effects on food production from plant and animal origin (^{Suber et al. 2019}). Tropical grasses, due to quality of Amazonian soils are characterized by having low productive yields and low nutritional quality, reasons for which farmers need to find new materials that help to improve the food supply and non conventional raw matters for cattle supplementation (^{Calderón et al.2017}). Considering the problem, it is urgent to restructure livestock to sustainable production systems, in which grass monocultures of foreign varieties were replaced by grasses with less water requirement and perennial plant species and supplementation with native or adapted forages, as well as browsing practices in secondary vegetation (^{Gómez et al. 2017}).

The use of tree forages with high nutritional value can contribute to the mitigation of the climate change (^{Restrepo et al. 2016}), because they increase the degradability for the high protein contents they have and decrease the methane production in rumen(^{Cardona Iglesias et al. 2016} and ^{Sánchez et al. 2018}). The nutritional supplements have acquired great importance, because they allow improving the body condition of the animals, the ovarian activation, the embryonic development and the reproductive indicators (^{Kubovičová et al. 2013}).This inclusion can only reached by knowing the degradability of the food resources that the region have, to optimized the use of alternative food sources in the animal feeding in the Amazonian piedmont (^{Gutiérrez 2015}). The objective of this study was to evaluate the ruminal degradability of supplements with the inclusion of native forages and adapted to the Amazonian piedmont conditions.

Materials and Methods

Experimental procedure. The study was carried out at Villa Lucero farm, located in Puerto Asís municipality, Santana Corregimiento, at coordinates: 0°35'25.6 "N and 76°32'05.3" W in Putumayo department, located at southwest of Colombia Republic, with 256 m o.s.l., average temperature of 25.3ºC, 85 % relative humidity and 3355 mm of annual precipitation (IDEAM 1997-2017), that corresponds to the tropical humid forest (^{Holdridge 1982}).

The samples of Trichantera gigantea (Tg), Piptocoma discolor (Pd) and Hibiscus rosa-sinensis (H. r-s), were harvested from a forage bank established in the farm, with plants one year of age, to which an agronomic management of cutting, insect and weed control was performed. An establishment cut was made and the plants regrowth at 60 days was used.

A total of seven treatments were formulated in accordance to the ^{NRC (2001)} recommendations. Each treatment consisted in a proportion of 20 - 40 % of forages in the supplement, in the following way:

• [T1 Control]. Commercial supplement

• [T2]. Commercial supplement with 20 % inclusion of Tg.

• [T3]. Commercial supplement with 40 % inclusion of Tg.

• [T4]. Commercial supplement with 20 % inclusion of Pd.

• [T5]. Commercial supplement with 40 % inclusion of Pd.

• [T6]. Commercial supplement with 20 % inclusion of H.r-s.

• [T7]. Commercial supplement with 40 % inclusion of H. r-s.

The collected forages were previously dried for 48 h in a forced air oven at 60 ºC. Later the dried material was homogenized and milled in a hammer mill with 2.5 mm sieve. The supplements were prepared as table 1 show. A total of 200g of sample per treatment were taken for laboratory analysis and other 200g for in situ ruminal degradability studies.

Table 1 Ingredients and chemical composition of the evaluated treatments (DM) 

Ingredient	T1	T2	T3	T4	T5	T6	T7
% (DM)
T. gigantea		20	40
P. discolor				20	40
H. rosa-sinensis						20	40
Corn meal	11.00	35.03	35.00	43.00	30.50	11.80	40.00
Soybean cake	5.80	0.84	0.00	0.20	0.00	4.11	2.40
Corn bran	76.70	37.12	18.00	30.30	24.00	57.08	12.10
Palm oil	0.50	1.00	2.00	0.50	0.50	1.00	0.50
Molasses	5.00	5.00	4.00	5.00	4.00	5.00	4.00
Microminerals ^a	1.00	1.00	1.00	1.00	1.00	1.00	1.00
Nutritional composition (%)
Treatments								AB
DM, %	88.7	89.08	90.22	89.81	91.57	88.88	90.66	27.99
OM %	96.87	96.3	94.04	96.2	95.0	97.14	95.82	92.69
Ether extract, %	4.96	6.44	9.32	6.98	7.98	2.72	5.65	1.95
Crude protein , %	11.53	11.50	12.49	11.78	13.95	11.50	11.54	6.33
NDF, %	49.03	50.56	52.57	45.83	52.12	53.99	53.98	-
ADF, %	28.32	26.81	28.06	28.27	29.27	28.90	31.76	-
ME, MJ /kg DM	11.79	11.50	11.50	11.76	11.98	11.51	11.83	6.63

^a Content of the microminerals mixure: Magnesium 10%, Zinc 10%, Iron 10%, Copper 2%, Iodine 0.12%, Selenium 0.06%, Cobalt 0.02%. AB: Brachiaria decumbens

The treatments were prepared in the laboratory of biotecnología del Centro Agroforestal y Acuícola Arapaima del SENA, Putumayo Regional. Table 1 shows the chemical composition of treatments.

Ruminal degradability. The in situ ruminal degradability studies were carried out with three male Pelibuey sheeps of 40 kg body weight (^{Campos et al. 2006}), cannulated in rumen, and housed in individual cubicles with free access to water and forage. The animals intake fresh forage of Brachiaria decumbens ad libitum and 200g of commercial concentrate for sheep, offered once a day (8:00 am).

The determination of the in situ ruminal degradability of dry matter (DM), organic matter (OM), neutral detergent fiber (NDF) and acid detergent fiber (ADF) of the different treatments was carried out according to the nylon bags procedure with an average porosity of 1.200 to 1.600 orifice per cm², with 12x8 cm size, previously weighed and correctly identified, according to procedure described by ^{Mehrez and Ørskov (1977)}.

A total of 5g of sample from each supplement per bag were weighed, that were triplicate at a rate of a bag for each animal, which correspond to a replication, for each incubation hours. At 8:00 am, seven bags were placed in the rumen (one for each treatment), in each animal, in a way that at every incubation time (3, 6, 12, 24, 48 and 72 hours) they could be removed. For 0 hour, three bags were leave without incubate to determine the quickly soluble fraction (A), which was obtained by the sample incubation in a water bath at 39 ºC for 30 minutes.

After being extracted from the rumen each bag was manually washed with water until obtaining a clear wash liquid. They were dried in a forced air oven at 65 ºC for 48hours.The bags wastes corresponding to the three repetitions of each incubation time in each animal were milled until reached a 1 mm particle size and an homogeneous sample was constituted to which OM was determined according to ^{AOAC (2016)}. To determine the degradation of these nutrients in the rumen, the proximate chemical analysis (PCA) were carried out in accordance with the procedures and recommendations established by ^{AOAC (1995)} in the following way: humidity content (Method 930.04), crude protein by de Kjeldahl (N*6.25) (method 955.04) method, ashes (calcination method 930.05), ether extract (method 962.09) and NDF and ADF by ^{Goering and Van Soest (1970)} method.

Estimation of the degradation. The exponential model proposed by ^{Ørskov and McDonald (1979)} was used, assuming that the degradation curves of DM and OM in time fallow a kinetic process of first order, which is describe in the way:

$P=A for t_0=0$

$P=a+b\left(1-e^{-ct}\right){ }_{t>t_0}$

And the degradation curves of NDF and ADF are described according to ^{Dhanoa (1988)} by the formula:

$P=A for t=t_0{}_{}$

$P=a+b{\left(1-e{{\displaystyle }}^{-c(t-L)}\right)}_{t>t_0}$

Where:

P	- Ruminal degradation. Is the ruminal degradation of the evaluated indicator in the stay time “t “in the rumen
a	- Intercept
b	- Fraction that is degrade in the time t.
c	- Degradation rate of the fraction “b”.
t	- Incubation time.
L	- Latent time or “lag” (hours). Time the rumen microorganisms use to colonize the cell walls of forages and adhere to them.
A	- Quickly soluble fraction

To determine the ruminal Effective Degradability (ED) the ^{McDonald (1981)} model was used.

$$

$ED=A+\left(\frac{Bc}{c+k}\right)$

Where:

k	- Fractional rate of ruminal passage . It is assumed k value (0.044 fraction h^-1) (^NRC 2001)
B	- Insoluble fraction but potentially degradable. B= (a+b) -A (^Ørskov 2002)
c	- Degradation rate of the fraction B

Statistical analysis. To determine the effect of the inclusion of forage species on the treatments a completely random design with factorial arrangement (3x2) was used with a control in which the mixture of the levels of the factors forages species and inclusion percentage in each incubation were considered as treatments with three repetitions which corresponded to each bag with the supplement. The results were analyzed by ANOVA thruogh the InfoStat statistical program (^{Di Rienzo et al. 2012}).When there were differences (P<0.05), the treatments means were compared by the ^{Duncan (1955)} test.

For the mathematical estimation of the ruminal degradation parameters of DM, OM, NDF and ADF of the evaluated supplements, the NEWAY EXCEL (^{Chen 2000}) program was used.

Results and Discussion

A supplements degradability analysis was carried out, in different incubation times, with the forages H. rosa-sinensis, T. gigantea and P. discolor, and their inclusion percentage (20 and 40%).There was interaction between the species and the inclusion level (P<0.05) for the DM degradability in the 3, 6, 24 and 72 hours. The treatments that reached the highest in situ ruminal degradability of the DM (P=0.0185), at 72 incubation hours, corresponded to the H. rosa- sinensis at 20% and P. discolor at 20% treatments, with 84.6 and 81.5 %,respectively; the ones did not differ from the treatment with H. rosa-sinensis at 40%, and T. gigantea at 20% (table 2).

Table 2 In situ ruminal degradation of DM (%) of supplemnts, with T. gigantea, P. discolor and H. rosa-sinensis inclusion. 

Hour.	Control	Treatments.^1						SE Sign.
		20% Tg	40% Tg	20% Pd	40% Pd	20% H. r-s	40% H. r-s
3	36.71 ^a	30.36 ^abc	19.36 ^bc	21.02 ^bc	17.42 ^c	20.26 ^bc	33.33 ^ab	±4.20 P=0.0374
6	39.13 ^a	41.84 ^a	29.96 ^bc	25.20 ^c	22.24 ^c	23.91 ^c	35.01 ^ab	±2.79 P=0.0037
24	65.69 ^ab	60.05 ^b	47.82 ^c	45.44 ^c	31.24 ^d	72.38 ^a	41.82 ^cd	±3.66 P=0.0486
72	91.84 ^a	76.03 ^b	52.74 ^d	81.58 ^b	67.32 ^c	84.65 ^ab	79.21 ^b	±2.34 P=0.0185

¹ Tg: T. gigantea, Pd: P. discolor. H. r-s: H rosa-siensis

^a,b,c,d: different letters per row show significant differences for P<0.05

SE: Standard Error

When the DM degradability at 12 and 48 incubation hours was analyzed, there was not interaction between the factors (P>0.05). That why, the individual factors of species and inclusion percentage were separately analyzed. When studying the species, it was observed that the H. rosa-sinensis and T. gigantea had similar performance, it differentiated of P. discolor at 48 incubation hours (P=0.0184).While the 40% inclusion had negative effect (P<0.0001) with 49.1% compared to the control (table 3).

Table 3 In situ ruminal degradation of DM (%) of supplements at 12 and 48 hours. 

Hour	Control	Species			SE Sign.
		T. gigantea	P. discolor	H. rosa- sinensis
12	46.27 ± 4.87	41.63	31.06	42.81	±3.45 P=0.0574
48	82.77 ^a ± 4.40	63.10 ^b	52.32 ^c	66.05 ^b	±3.11 P=0.0184
12	Control	20%	40%		±2.81 P=0.0341
	46.27 ^a ± 4.87	43.17 ^a	33.83 ^b
48	82.77 ^a ± 4.40	71.89 ^a	49.09 ^b		±2.54 P<0.0001

^a,b,c,d: different letters per row show significant differences for P<0.05

SE: Standard Error

Respect to the OM degradability, there was interaction between the species and the inclusion level (P<0.05) in 3, 6 and 72 hours. The treatments that reached high in situ ruminal degradability of the OM (P=0.0098), at 72 incubation hours, corresponded to the H. rosa-sinensis at 20% and P. discolor at 20% treatments, with 72.8 and 70.1 % respectively, the ones did not differ from the treatment with H. rosa-sinensis at 40%, and T. gigantea at 20% (table 4).

Table 4 In situ ruminal degradation of OM (%) of supplements, T. gigantea, P. discolor e H. rosa-sinensis inclusion. 

Hour.	Control	Treatment^1						SE Sign
		20% Tg	40% Tg	20% Pd	40% Pd	20% H. r-s	40% H. r-s
3	31.44^a	26.11^abc	16.32^c	18.08^bc	15.08^c	17.42^bc	28.96^ab	±3.63 P=0.0308
6	33.51^a	35.98^a	25.25^bc	21.67^c	19.26^c	20.56 ^c	30.42^ab	±2.40 P=0.0027
72	78.65^a	65.38^bc	44.46^d	70.15^b	58.30^c	72.79^ab	68.83^b	±2.34 P=0.0098

¹ Tg: T. gigantea, Pd: P. discolor. H. r-s: H rosa-siensis

^a,b,c,d: different letters per row show significant differences for P<0.05

SE: Standard Error

When analyzing the OM degradability at 12, 24 and 48 incubation hours, there was not interaction (P>0.05), that is why, the individual factors of species and inclusion percentage were analyzed. The supplement with H. rosa-sinensis obtained the highest value at 48 hours (P=0.0098), fallow by T. gigantea with 57.0 and 53.8%, respectively; without differences between them, which differed of P. discolor. While the inclusion at 40 % had negative effect (P<0.0001) with 42.2% compared to the control (table 5).

Table 5 In situ ruminal degradation of OM (%) of supplements at 12, 24 and 48 hours. 

Hour	Control	Species			SE Sign.
		T. gigantea	P. discolor	H. rosa-s.
12	39.63 ± 4.20	35.49	26.79	36.99	±2.97 P=0.0606
24	56.26 ^a ±3.14	45.97 ^b	33.07 ^c	49.29 ^ab	±2.22 P=0.0003
48	70.88 ^a ±3.78	53.83 ^b	45.12 ^c	57.04 ^b	±2.67 P=0.0190
12	Control	20%	40%		±2.42 P=0.0336
	39.63 ^a ± 4.20	37.12 ^a	29.05 ^b
24	56.26 ^a ± 3.14	50.98 ^a	34.57 ^b		±1.47 P<0.0001
48	70.88 ^a ± 3.78	61.82 ^a	42.17 ^b		±2.18 P<0.0001

^a,b,c,d: different letters per row show significant differences for P<0.05

SE: Standard Error

The characteristics of the high ruminal degradability showed the high nutritional quality of the evaluated supplements and suggest the feasibility of the use of these for ruminant supplementation. All this observations are also related with the results obtained by ^{Cáceres y González (2015)} who obtained ruminal degradability values of 67.2% for OM and 76.2% of DM and 79.3-84.2 % with H. rosa-sinensis hay (^{Navarro and Roa 2018}). However the results of this study were higher. It possible that the inclusion of 20% increased the degradation that ruminal microorganisms made to the carbohydrates presents in the supplement.

When the treatments degradability with 40% of inclusion is analyze, some forage trees in the tropic had showed a possible effect as defaunating in ruminants. This is due to the presence of phenolic substances or other secondary metabolites in their leaves (^{Saavedra 2017}). However, it is known that there is adaptation to these compounds through the degradation, neutralization of the active molecules and tolerance mechanism development, which explain that these observed effects have limited persistence in the degradability in accordance with the inclusion levels in the diet, as had being observed in in vivo studies (^{Bodas et al. 2012}).

The action of the microorganisms face to secondary metabolites content in forages could be a limitation of the OM degradability, which probably happen in the T. gigantea at 40% and P. discolor at 40% treatment, given the high inclusion percentage. To solve it is recommended to rotational supplied in the animals diet, in browsing or incorporate to supplements for adapting the microorganisms to their presence (^{Patra y Saxena 2010}).

In relation to the P. discolor, ^{Castañeda et al. (2017)} found 27 % of in vitro DM degradability for the forage. These results were lower to those found in this study, with 81.6 % for DM and 70.2% for OM in the supplement mixture. They were high possibly by the particular conditions of the P. discolor, by their high CP content and energy and the inclusion level of 20%.In addition, this forage could have great amount of soluble compounds available for the animal such as amino acids and peptides; as well as short change fatty acid branched that favors the needed synchronization of nitrogen and energy for the rumen microorganisms, specifically the cellulolytic and ruminal degradation of nutrients and therefore it could showed high degradability values in all the analyzed incubation period (^{Ducuara and Suárez 2013}).The P. discolor as being a tree have higher protein content than the forages normally used in animal feeding and consequently they can be use as diet supplement.

In the same way the use of non conventional species, in in vitro degradability studies, the results found in the H. rosa-sinensis species were higher to those described by ^{Milera, (2013)} with OM degradation of 71.3% and ^{Pinto et al. (2009)} studies with 70.0%, and lower to those reported by ^{Navarro and Roa (2018)} with 87% of DM degradability.

The H. rosa-sinensis forage had the highest degradability of all evaluated treatments, respect to its biological value, without differences with P. discolor. However, as not being a native forage from the Amazonia, is vulnerable to pests, because of their good palatability. In the same way, the nutrients level of the forage were low with respect to T. gigantea and P. discolor (^{Burgos et al. 2015)}, which is a disadvantage in supplementation programs in which amount of biomass with optimum levels of protein are looking for (Figueroa 2017).

As regard, in T. gigantea there is a high variability in the nutritive composition, by the genetic conditions and other factors as climate and soil, with a high fermentation because of the carbohydrates concentration (^{Rosales 1996}), which was observed at 24 and 48 hours of this study. The degradation of the soluble fraction was high compared to other forages, additionally could be a good source of bypass protein in rumen (^{Edwards et al. 2012}). However that degradability can be affected by the phenols presence (^{Galindo et al. 1989}) and tannins. Respect to this last secondary compounds, ^{Rodríguez et al. (2016)} found higher biological effect of tannins in gas production, degradability of the OM, NDF, ME and NH₃ concentration. However, this aspect does not justify the low nutritive value attributed to this species, probably because this could be the result of the effect combined with their high fiber content (^{Rodríguez et al. 2014}).Simultaneously, the mixtures of this forage with conventional raw matter as corn, besides the drying, reduce the toxicity level in particular (^{McCann and Loor 2017})with synergic effects to digestive level of the mixture components for increasing the diet palatability, to use the degradation in rumen.

When observing the NDF degradability, there was interaction between the species and the inclusion level (P<0.05) at 6 and 72 hours. The treatments with the in situ ruminal degradability of the NDF was high (P=0.0005), at 72 incubation hours, corresponded to the treatment H. rosa- sinensis at 40 % and H. rosa-sinensis at 20%, with 51.3 and 47.5 %, respectively (table 6).

Table 6 In situ ruminal degradation of NDF (%) of supplements, with T. gigantea, P. discolor and H. rosa-sinensis inclusion. 

Hour.	Control	Treatment^1						SE Sign
		20% Tg	40% Tg	20% Pd	40% Pd	20% H. r-s	40% H. r-s
6	24.18 ^a	21.31 ^a	15.26 ^bc	10.88 ^c	12.49 ^c	12.36 ^c	20.42 ^ab	±1.87 P=0.0073
72	41.70 ^c	35.51 ^d	28.37 ^e	45.88 ^b	36.21 ^d	47.50 ^ab	51.29 ^a	±1.37 P=0.0005

¹ Tg: T. gigantea, Pd: P. discolor. H. r-s: H rosa-siensis

^a,b,c,d: different letters per row show significant differences for P<0.05

SE: Standard Error

There was not interaction (P>0.05) at 3, 12, 24 and 48 hours, for NDF degradability. For this, the individual factors of the species and the inclusion percentage were analyzed. The H. rosa-sinensis obtained the highest value (P=0.0011) at 48 hours fallow by T. gigantea with 40.0% and 36.1 %, respectively, without differences between them, which differed of P. discolor. While the inclusion at 40% had negative effect (P<0.0001) with 27.3 % compared with the control (table 7).

Table 7 In situ ruminal degradation of NDF (%) of supplements at 3, 12, 24 and 48 hours. 

Hour	Control	Species			SE Sign.
		T. gigantea	P. discolor	H. rosa-s.
3	18.48 ± 2.30	13.16	9.61	14.92	±1.62 P=0.0965
12	26.90 ^a ± 2.60	20.40 ^ab	16.40 ^b	25.77 ^a	±1.84 P=0.0110
24	38.07 ^a ± 2.08	29.62 ^b	20.41 ^c	33.88 ^ab	±1.47 P<0.0001
48	40.70 ^a ± 2.49	36.10 ^a	28.30 ^b	39.99 ^a	±1.76 P=0.0011
3	Control	20%	40%		±1.33 P=0.6961
	18.48 ± 2.30	12.19	12.94
12	26.90 ± 2.60	22.96	18.76		±1.50 P=0.0686
24	38.07 ^a ± 2.08	33.51 ^a	22.43 ^b		±0.56 P<0.0001
48	40.70 ^a ±2.49	42.33 ^a	27.26 ^b		±1.44 P<0.0001

^a,b,c,d: different letters per row show significant differences for P<0.05

SE: Standard Error

It was verified that for the in situ ruminal degradability of ADF there was interaction between the species and the inclusion level (P<0.05) at 3, 24 and 72 hours. The treatments with higher in situ ruminal degradability of ADF (P=0.0098), at 72 incubation hours, corresponded to treatment H. rosa-sinensis at 40% and H. rosa-sinensis at 20%, with 25.3 and 24.6 %, respectively which differed of T. gigantea 40.0% with 14.5 % (table 8).

Table 8 In situ ruminal degradation of ADF (%) of supplements, with T. gigantea, P. discolor and H. rosa-sinensis inclusion. 

Hour.	Control	Treatment ^1						SE Sign
		20% Tg	40% Tg	20% Pd	40% Pd	20% H. r-s	40% H. r-s
3	10.52 ^a	8.24 ^ab	5.51 ^b	5.35 ^b	5.35 ^b	5.76 ^b	10.27 ^a	±1.26 P=0.0374
24	20.53 ^a	17.17 ^b	13.59 ^c	12.16 ^cd	9.39 ^d	22.03 ^a	13.20 ^c	±1.09 P=0.0297
72	24.35 ^a	19.49 ^b	14.53 ^c	24.62 ^a	17.94 ^b	24.39 ^a	25.31 ^a	±0.73 P=0.0098

¹ Tg: T. gigantea. Pd: P. discolor. H. r-s: H rosa-siensis

^a,b,c,d: different letters show significant differences for P<0.05

SE: Standard Error

At 3, 12, 24 and 48 incubation hours, there was not interaction (P>0.05), that’s why the individual factors of the species and the inclusion percentage were separately analyzed. The H. rosa-sinensis obtained the highest value (P=0.0024) at 48 hours with 21.1 %, that differed of the other evaluated forages. While the inclusion at 40 % had negative effect (P<0.0001) with 14.4 % compared to the control (table 9).

Table 9 In situ ruminal degradation of ADF (%) of supplements at 3, 12 and 48 hours. 

Hour	Control	Species			SE and Signif.
		T. gigantea	P. discolor	H. rosa-s.
6	12.19 ^a ± 0.97	12.97 ^a	6.05 ^c	8.65 ^b	±0.69 P<0.0001
12	14.22 ^a ± 1.36	11.19 ^ab	8.48 ^b	13.81 ^a	±0.96 P=0.0056
48	22.76 ^a ± 1.31	17.84 ^b	15.37 ^b	21.10 ^a	±0.93 P=0.0024
6	Control	20%	40%		±0.56 P<0.0001
	12.19 ^a ± 0.97	7.44 ^b	11.01 ^a
12	14.22 ± 1.36	12.35	9.97		±0.79 P=0.0502
48	22.76 ^a ± 1.31	21.83 ^a	14.38 ^b		±0.76 P<0.0001

^a,b,c,d: different letters show significant differences for P<0.05

SE: Standard Error

The DM and OM degradability is limited by the NDF and ADF concentration of forage and especially by lignin concentration. That’s why the supplement that showed the higher values of ruminal degradability of DM and OM were the treatments with the H. rosa-sinensis and P. discolor inclusion, which differed of the treatment with the inclusion of 20% of T. gigantea, because these species have low content of these compounds (^{Meza et al. 2014}).

With respect to the kinetic parameters of ruminal degradability of the different evaluated treatments (table 10 and table 11), the used model had high goodness of fit, because R² was high, superior 0.80 for the analyzed fractions, which showed that this model was able to explain a high percentage of the variation of ruminal degradability real data.

Table 10 Ruminal kinetic parameters and effective degradability of DM and OM in sheep supplements. 

Parameter	Control	Treatments^1
		20% Tg	40% Tg	20% Pd	40% Pd	20% H. r-s	40% H. r-s
DM
A (%)	5.2	3.2	6.5	1.3	2.3	4.1	1.6
B (%)	94.8	75.4	45.7	98.7	97.7	80.3	98.4
(A+B)(%)	100	78.6	52.1	100	100	84.4	100
C (Fraction h^-1)	0.017	0.054	0.089	0.012	0.001	0.068	0.001
R^2	0-99	0.99	0.99	0.98	0.94	0.98	0.94
ED (%) k= 0.02	71.2	60.7	44.6	58.1	48.3	65.5	60.9
OM
A (%)	4.5	2.8	5.5	1.1	2.0	3.5	1.3
B (%)	95.5	64.8	37.9	98.9	98.0	69.0	98.7
(A+B) (%)	100	67.6	43.4	100	100	72.5	100
C(Fraction h^-1)	0.017	0.054	0.062	0.012	0.02	0.068	0.001
R^2	0.99	0.99	0.80	0.98	0.96	0.98	0.94
ED (%) k= 0.02	61.1	52.2	34.5	50.0	41.8	56.3	52.7

¹ Tg: T. gigantea, Pd: P. discolor. H. r-s: H rosa-siensis

A: Soluble fraction. B: Insoluble fraction. A+B (%): Potential degradation. C: Degradation rate ED: Effective degradability. R²: Determination coefficient belonging to the model.

Table 11 Ruminal kinetic parameters and effective degradability of NDF and ADF in sheep supplements. 

Parameter	Control	Treatments ^1
		20% Tg	40% Tg	20% Pd	40% Pd	20% H. r-s	40% H. r-s
NDF
A (%)	2.6	1.6	3.4	0.6	1.2	2.2	0.8
B (%)	42.4	39.9	25.5	80.6	98.8	46.5	99.2
(A+B)(%)	45.0	41.5	28.9	81.2	100	48.7	100
C (Fraction h^-1)	0.041	0.062	0.078	0.010	0.001	0.076	0.002
L (h)	0	0	0	0	0	1.1	0
R^2	0.99	0.89	0.99	0.98	0.97	0.97	0.94
ED (%) k= 0.02	35.4	32.3	24.2	32.3	26.2	38.1	37.6
ADF
A (%)	1.5	0.9	1.8	0.4	0,7	1.2	0.5
B (%)	26.6	20.5	12.4	55.8	89.1	24.1	99.5
(A+B) (%)	28.1	21.3	14.2	56.2	89.8	25.3	100
C (Fraction h^-1)	0.027	0.060	0.105	0.007	0.002	0.080	0.001
L (h)	0	0	0	0	0	1.3	0
R^2	0.99	0.95	0.98	0.99	0.97	0.97	0.93
ED (%) k= 0.02	20.0	16.6	12.3	17.5	13.4	19.9	19.1

¹ Tg: T. gigantea, Pd: P. discolor. H. r-s: H rosa-siensis

A: Soluble fraction. B: Insoluble fraction. A+B (%): Potential degradation. C: Degradation rate. ED: Effective degradability. L: lag phase. R²: Determination coefficient belonging to the model

The ruminal kinetic depend on two critical aspects: the speed to begin the degradation and the degradation rate (parameter c). The combination of these two aspects establish net amount of microorganisms that synthesized the nutrients and later are used and digested in the abomasums and intestine. The results confirmed the superiority of the effective degradability of DM, OM, NDF and ADF of the treatments with 20% of forages inclusion, compared with the control.

The changes occurred in the nutritional contribution of the different mixtures in the treatments could determined the increase or decrease of NDF and ADF, that influence on the supplements degradability. In that context, these changes influenced the fermentative action at ruminal level, accessibility of microorganisms to the cell wall of forages and the stimulation or reduction of the ruminal celluloses and material degradation (^{Núñez and Rodríguez 2019}).

The treatment with H. rosa-sinensis at 20% and T. gigantea at 20% showed effective degradation more high for DM and OM, respectively. In the same way the treatment H. rosa-sinensis at 20% and P. discolor at 20% had similar kinetic for NDF and ADF variables (table 10 and table 11).This performance could be related with the lower fiber content that showed these treatments compared with the rest of the evaluated treatments, so it showed higher proportion of soluble compounds and lower proportion of the structural constituents of the cell wall which favors their higher degradability.

The parameters of the fermentation kinetic described the digestion and characterized intern properties of the food that limits their availability for the ruminant, determine the proportion of intake nutrients that could be use by the animal and depend on the microbial action of the rumen (^{Hernández et al. 2018}).The forage degradability in the rumen is related with the proportion and lignification of the plant cell walls. In this way, the foliage of forage tress with low NDF content (20 -35 %) have normally high degradability (>50 %) and species with high lignin content have low degradability (< 50 %) (^{Bruni and Chilibroste 2001}).

With respect to the “lag phase” or latent period, intimately related with the time that use the microorganisms to colonized the fiber, adhered to cell walls and binging their catabolic action, there were values of 1.1 and 1.3 hours for the treatment with H. rosa-sinensis at 20% (tables 10 and 11), for NDF and ADF, respectively. These could be influenced by fiber content of H. rosa-sinensis contained in the supplement, when the microorganisms requiring more time to colonized the substrate, the degradability level was higher. On the contrary, the other treatments reported “0” values. This performance could be attributed to a supplement with low NDF and ADF content was evaluated, which is consistent with studies performed by ^{Valenciaga et al (2018)} in different Tithonia diversifolia varieties.

In the case of the treatments with P. discolor at 20% and at 40%, the NDF effective degradability when comparing with conventional forages as morera were lower (^{Zach et al. 2017}).However, the DM and OM degradability was statistically comparable with H. rosa-sinensis at 20% and at 40%,respectively showed a higher degradability. This is an important indicator of the forage quality of this native tree from the Colombian Amazonian, possibly due to the quantity of NDF, ADF and lignin are not high. ^{Ducuara and Suárez (2013)} consider a good quality tree with degradability higher than 50%,with a positive factor in the forage intake or in a supplement (^{Calle et al. 2012}). Since is considered that a forage have high quality when it approximately have 70% of DM degradability, less than 50% of NDF and more than 15% of CP (^{Cardozo 2013}), it should highlighted that the inclusion of P. discolor and T. gigantea at 20% in the supplement are viable alternatives for ruminants feeding.

Conclusion

The ruminal kinetic and in situ ruminal degradability of the AM, OM, ADF and NDF, in the H. rosa-sinesis, P. discolor and T. gigantean species, suggested the high nutritional value of these species in ruminant diets. Supplements with the inclusion of 20 % of the evaluated forages, is a viable option from the point of view of nutritional supply for animals, in supplementations programs for ruminants under the Amazonian piedmont.

Acknowledgments

The authors thank the support in the processing of the statistician data to Lic. Yolaine Medina Mesa, Dra Magaly Herrera, biomathematics group and Dr. Rafael Rodríguez from the Instituto de Ciencia Animal and in field activities to the manager of Villa Lucero farm: Rosa Amelia Quiroz and Leidy Milena Daza (auxiliar de investigación). As well as Servicio Nacional de aprendizaje SENA, Laboratory of wáter, soils and biotechnology project SENNOVA, Regional Putumayo, Colombia.

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Received: November 14, 2019; Accepted: March 23, 2020

^*Email: riascos @ica.co.cu