Effects of strategic supplementation on average daily gain and feed conversion ratio of Brahman heifers under grazing systems in the Ecuadorian Amazon

Efeitos da suplementação estratégica no ganho médio diário e na taxa de conversão alimentar de novilhas Brahman em sistemas de pastagem na Amazônia Equatoriana

Abstract

Cattle farming in the Ecuadorian Amazon, being extensive in nature, demonstrates low productivity and profitability indices. With these realities in mind, a study was conducted to evaluate strategic supplementation in grazing cattle. Using a crossover design over 60 days, 18 Brahman heifers were assigned into two homogeneous groups according to live weight. The first has been grazing without supplementation (T0 = 9), while the second group (T1 = 9) received a diet formulated with the NASEM 2021 feeding software, being designed to cover the nutritional deficiencies of pasture (crude protein < 8%). The feeding regime of T0 consisted of 100% grazing (Panicum maximum), whereas T1 grazed for 20 h/day and was provided with the diet in the stable during the remaining 4 h. All animals had free access to fresh water, shade, and a daily supply of 60 g of mineral salts. According to the results, live weight yielded highly significant differences (P < 0.001). In fact, the supplemented animals had almost three times higher average daily gain than those under the grazing-only regime (1.46 vs. 0.48 kg/day). Consequently, notable and marked differences were observed in feed conversion in the supplemented group (10.71 vs. 8.39), which was more evident in the second period (P < 0.001). Subsequently, it is confirmed that under tropical conditions with low-quality pastures, strategic supplementation constitutes a viable practice that contributes to improved productive and profitability indices for farmers within a framework oriented toward more sustainable production models in these fragile ecosystems.

Keywords:
strategic supplementation; Average Daily Gain (ADG); Feed Conversion Ratio (FCR); Brahman cattle; Ecuadorian Amazon

Resumo

A pecuária bovina na Amazônia equatoriana, por ser extensiva, apresenta baixos índices de produtividade e rentabilidade. Considerando essa realidade, foi realizado um estudo para avaliar a suplementação estratégica em bovinos em pastagem. Utilizando um delineamento cruzado ao longo de 60 dias, 18 novilhas Brahman foram alocadas em dois grupos homogêneos de acordo com o peso vivo. O primeiro grupo pasteou sem suplementação (T0 = 9), enquanto o segundo grupo (T1 = 9) recebeu uma dieta formulada com o software de alimentação NASEM 2021, elaborada para suprir as deficiências nutricionais da pastagem (proteína bruta < 8%). O regime alimentar do grupo T0 consistiu em 100% de pastagem (Panicum maximum), enquanto o grupo T1 pasteou por 20 h/dia e recebeu a dieta no estábulo durante as 4 h restantes. Todos os animais tiveram livre acesso a água fresca, sombra e uma dose diária de 60 g de sais minerais. De acordo com os resultados, o peso vivo apresentou diferenças altamente significativas (P < 0,001). De fato, os animais suplementados apresentaram ganho médio diário quase três vezes maior do que aqueles em regime de pastoreio exclusivo (1,46 vs. 0,48 kg/dia). Consequentemente, diferenças notáveis ​​e marcantes foram observadas na conversão alimentar no grupo suplementado (10,71 vs. 8,39), sendo essa diferença mais evidente no segundo período (P < 0,001). Assim, confirma-se que, em condições tropicais com pastagens de baixa qualidade, a suplementação estratégica constitui uma prática viável que contribui para a melhoria dos índices de produtividade e rentabilidade para os produtores, dentro de um contexto orientado para modelos de produção mais sustentáveis ​​nesses ecossistemas frágeis.

Palavras-chave:
suplementação estratégica; Ganho Médio Diário (GMD); Taxa de Conversão Alimentar (CA); gado Brahman; Amazônia Equatoriana

1. Introduction

Extensive livestock farming in most of Latin America is based on grazing systems (Flores-Coello et al., 2023). Hereby, it was stated that relying exclusively on grazing, without adequate supplementation strategies, results in average daily weight gains of only 250 grams in the Ecuadorian Amazon, leading to low yields and poor profitability (Goldansaz et al., 2017; Kyriazakis et al., 2024; Guamán-Rivera et al., 2023a). Furthermore, the lack of knowledge about supplementation limits the development of efficient nutritional practices, affecting not only growth but also reproductive efficiency and disease resistance. The consequences of these deficiencies are not limited to growth performance; inadequate nutrition can also compromise reproductive efficiency, immune function and the overall resilience of livestock to environmental stressors, thereby reducing herd productivity and increasing susceptibility to disease (Chaves et al., 2021; Machado et al., 2022). At the same time, there is growing pressure to improve the sustainability of tropical livestock systems, given their potential contribution to greenhouse gas emissions and deforestation, particularly in border regions such as the Amazon (Huera-Lucero et al., 2020). In this context, developing feeding strategies that simultaneously improve production performance and steer systems towards more sustainable models has become a key challenge for researchers, advisers and producers (Rudel et al., 2015). From this perspective, strategic supplementation has emerged as a promising tool for addressing the nutritional deficiencies typical of tropical pastures and improving animal performance under grazing conditions-(Montagnini, 2008). Some studies have shown that, when supplementation adequately meets both basic requirements and the additional demands associated with growth or production, daily weight gain and feed efficiency can improve significantly compared with regimes based solely on grazing (Fuentes et al., 2022). These responses depend on the composition and level of supplementation, as well as on the characteristics of the pasture (plant composition, crude protein content, digestibility) and grazing management (Beauchemin et al., 2022). Specifically, in systems dominated by grasses such as Panicum maximum or Brachiaria spp., crude protein concentrations of less than 8–9% on a dry matter basis are common; this can restrict intake and microbial activity in the rumen, thereby limiting the animals’ performance if no supplementary dietary sources are provided (Dijkstra et al., 2002).

To our knowledge, this is one of the first controlled studies to evaluate the effects of a NASEM 2021-formulated strategic supplement based on locally available by-products such as palm sludge and molasses on the productive performance of Brahman heifers grazing Panicum maximum in the Ecuadorian Amazon. By addressing this gap, the study not only contributes empirical data to the regional scientific literature but also offers a replicable, low-cost nutritional strategy aligned with circular economy principles and sustainable intensification goals (Rudel et al., 2015; Huera-Lucero et al., 2020). In this regard, this study was conducted in the province of Orellana, in the Ecuadorian Amazon, to assess the effect of strategic nutritional supplementation on the productive performance of Brahman heifers reared in grazing systems. We hypothesized that, under the nutritional and environmental constraints characteristic of the Ecuadorian Amazon, strategic supplementation would significantly increase average daily gain and improve feed conversion compared with non-supplemented grazing, thereby offering a viable alternative to enhance productivity and profitability while moving toward more sustainable livestock production models in this fragile ecosystem.

2. Materials and Methods

2.1. Study area

The current research was performed in the province of Orellana, specifically in the canton of Joya de los Sachas, within the community of Huamayacu, below the coordinates -0.336794, -76.914744 (GADPO, 2015). The main cultivated grass species is Panicum maximum, which was established 8 years ago at a sowing rate of 3 kg/ha⁻¹ and an initial fertilization of 150 kg/ha⁻¹ with urea (N46). Panicum maximum grass was managed under rotational grazing in 12 paddocks of 0.15 ha each, with grazing periods of 3 days and rest periods of 33 days. Forage availability ranged between 3,000 and 4,000 kg DM/ha per cycle, with a stocking rate of 9 head/ha. Proximate analysis showed a crude protein of 10.5% DM, NDF of 62% DM, ADF of 37% DM, and dry matter digestibility of 60%.

2.2. Animals and treatments

Within a 2 × 2 crossover design, a total of 18 Brahman heifers (initial live weight: 319.2 ± 24 kg) were first stratified by weight and then randomly assigned to one of two treatment sequences (AB or BA) using a computer-generated randomization list (PROC PLAN, SAS v.9.4). Treatment A (T0) consisted of 24-hour grazing on Panicum maximum without supplementation, while Treatment B (T1) comprised 20-hour grazing plus a supplemental ration offered in the stable during the remaining 4 hours. The study included two experimental periods of 30 days each, separated by a 7-day washout period during which all animals grazed without supplementation to minimize potential carryover effects. Prior to the start of Period 1, all animals underwent a 7-day adaptation period under uniform grazing conditions with ad libitum access to water and mineral salts, ensuring a standardized baseline for treatment comparison. The supplemental diet was formulated using the NASEM 2021 program (corn silage, palm sludge, ground corn, urea, mineral salt, molasses, and bypass fat), mixing the ingredients in a TMR (Total Mixed Ration) mixer attached to a tractor, ensuring adequate homogenization. In terms of composition, this ration provides between 13 and 15% crude protein on a dry matter basis, a neutral detergent fiber (NDF) content of around 35%, and an ether extract of approximately 4% due to the incorporation of palm sludge and bypass fat. The ash content is also around 4%, while the net energy gain (NEg) ranged from 1.3 to 1.5 Mcal/kg of dry matter, making these diets balanced and efficient for promoting animal productivity.

2.3. Experimental variables

During the experimental period, the animals’ live weight was monitored weekly, with data recorded every 7 days using a digital scale. At the same time, body condition score (BCS) was assessed through observation and palpation, using a scale of 1 to 9 in accordance with the methodology of Ferguson et al. (1994). Feed Conversion Ratio (FCR) Calculation: FCR was calculated as the ratio of total dry matter intake (kg) to total live weight gain (kg) over the experimental period. By this definition, a lower FCR value indicates greater feed efficiency, meaning less feed is required to produce one kilogram of weight gain.

Supplement intake: Measured daily by the weigh-back method (offer minus refusal), recorded on a fresh weight basis and converted to dry matter using representative subsamples dried at 60°C for 48 h. Forage intake during grazing: Estimated using the difference technique, validated for Panicum maximum under tropical grazing conditions (Guamán-Rivera et al., 2023b; Moore et al., 1999; Equation 1):

$$ForageDMI\left(kg/d\right)=TotalDMI\left(predicted\right)-SupplementDMI\left(measured\right)$$(Equation 1)

Where Total DMI (predicted) was estimated using the NASEM (2022; Equation 2) predictive equation for growing beef cattle grazing tropical grasses:

$$DM{I}_{pred}(kg/d)=0.018\times B{W}^{0.75}\times F{C}_{adj}\times Q_{adj}$$(Equation 2)

BW = body weight (kg)

FC = fill correction factor based on NDF content of Panicum maximum (62% DM)

Q = quality adjustment factor based on in vitro dry matter digestibility (IVDMD = 60%)

This equation has been validated for Brahman cattle grazing Panicum maximum in the Ecuadorian Amazon, with a reported prediction error of ±12% (Guamán-Rivera et al., 2023b). On the other hand, for grazing-only animals (T0), total DMI was estimated directly using the same NASEM (2022) predictive equation, as no supplement was provided.

3. Statistical Analysis

The data were analyzed using SAS software v.9.4. After verifying normality (PROC UNIVARIATE), the variables were analyzed using linear mixed models (PROC MIXED), appropriate for crossover designs with repeated measures. The model included treatment, period, week, and their interactions as fixed effects (Equation 3, while animal was included as a random effect to account for individual variability. Repeated measurements over time (week) were modelled within each animal using an appropriate covariance structure (autoregressive AR(1) was selected based on goodness-of-fit criteria).

The statistical model used was:

$$Y_{ijkl}=\mu +Ti+Pj+Wk+\left(T\times W\right)ik+Animall+\epsilon ijkl$$(Equation 3)

Where:

- Yijkl is the dependent variable,

- μ is the overall mean,

- Ti is the fixed effect of treatment,

- Pj is the fixed effect of period,

- Wk is the fixed effect of week,

- T×W is the interaction between treatment and week,

- Animall is the random effect of animal,

- εijkl is the residual error.

Least squares mean were compared using Tukey adjustment, and statistical significance was declared at P < 0.05.

4. Result

The data on live weight are presented in Table 1. Although the group that received supplements weighed on average 17 kg more than the group that did not receive them, the difference was not statistically significant (P = 0.69). This variation can be explained by the short duration of the experiment and the high variability between individuals. Nevertheless, the positive trend suggests that supplementation promotes weight gain, and a longer experimental period could provide further evidence in this regard.

Table 1
Least squares adjusted means T-Student over live weight.

Group	Mean	Standard Error	Mean difference	P-value
Non-supplemented	339	21	− 17.0 kg	0.69
Supplemented	356	23

Daily supplement intake generated a significant increase during the second period, rising by approximately 4 kg/day (P < 0.0001). This increase reflects better animal adaptation to the supplemental diet and a greater intake capacity over time, contributing to maximizing the benefits of the supplementation strategy (Table 2).

Table 2
Least squares adjusted T-Student means for supplement consumption.

Period	Mean	Standard Error	P-value
1	20.18	1.57	0.0001
2	24.22	1.88
Diff (1−2)	+4.04

Table 3 summarizes the main effects of treatment, period, and interaction (treatment x period) on the evaluated variables. The treatment effects were significant for weight gain (P < 0.0001) and feed conversion ratio (P = 0.006), confirming that supplementation improves these indicators. For live weight, the differences were not significant (P < 0.05), although a positive trend was observed. The results of this study demonstrate that strategic supplementation applied to grazing Brahman cattle significantly improved average daily gain and feed efficiency and demonstrated a positive trend in final live weight. The progressive increase in supplement consumption and the improvement in feed conversion indicates the animals' adaptation to the supplemental diet and the effectiveness of this strategy in enhancing productivity in grazing systems in the Ecuadorian Amazon region.

Table 3
Least squares adjusted means considering the main effects of week, period, and the week × period interaction.

Item	Strategies		Period		SEM	P = value
	Supplement	Grazing	Period 1	Period 2		Treatment	Period	Week	W× P
Live weight, kg	357	374	368	363	12	0.2	0.73	0.11	0.08
Weight gain, kg	1.46	0.5	1.15	0.82	0.59	0.0001	0.05	0.18	0.25
Feed conversion (FCR)	10	8	1.42	–	0.006	0.65	–	–

5. Discussion

Although extensive scientific evidence has demonstrated that extensive grazing systems are able to contribute to resource conservation (Baumont et al., 2000), these systems require significant amounts of natural resources and may negatively impact the environment through greenhouse gas (GHG) emissions (González Marcillo et al., 2021). Consequently, similar to the findings of (Barbero et al., 2015) and considering that, like Brazil, the Ecuadorian livestock systems heavily rely on pasture forage. (González Marcillo et al., 2021; Guamán-Rivera et al., 2023b) emphasize that effective management system planning is essential for optimizing production. Furthermore, preliminary studies reported by Fuentes-Quisaguano et al. (2023) and González Marcillo et al. (2021) in the province of Orellana in Eastern Ecuador indicate that 90% of the livestock system is based on monoculture pastures, resulting in a deficiency of legumes that are necessary for promoting high weight gain. Reference data from (Barbero et al., 2015) for Marandu (Brachiaria decumbens) yielded crude protein (CP) values greater than 12% on a dry matter basis. In contrast, the present analysis of the Panicum maximum revealed CP values of less than 9%. This disparity may be adversely affecting production parameters related to weight gain, suggesting that CP values for production animals should exceed 14% on a dry matter basis (Guamán-Rivera et al., 2023b). The baseline pasture (Panicum maximum) exhibited crude protein (CP) concentrations below 9% on a dry matter basis, a level widely recognized as suboptimal for supporting microbial protein synthesis in the rumen. Tropical grasses at this CP threshold typically limit ruminal ammonia-N availability, restricting the proliferation of fibrolytic bacteria and reducing overall forage digestibility (Dijkstra et al., 2002; Guamán-Rivera et al., 2023b). The supplemental diet, formulated using NASEM 2021 guidelines, directly addressed this nitrogen limitation by incorporating non-protein nitrogen (urea), degradable protein sources (palm sludge, corn silage), and rapidly fermentable carbohydrates (molasses, ground corn). This combination likely restored the synchrony between energy and nitrogen release in the rumen, a critical factor for maximizing microbial yield and volatile fatty acid (VFA) production (Moore et al., 1999; Lean et al., 2014). Improved synchronization enhances propionate synthesis, which serves as the primary glucogenic precursor for tissue deposition, thereby explaining the substantial increase in ADG observed in the supplemented group.

Furthermore, the inclusion of bypass fat and a balanced ether extract (~4%) provided a concentrated energy source that bypassed ruminal degradation, directly supplying metabolizable energy to the small intestine. This is particularly advantageous in tropical grazing systems, where low-quality forages often impose energy deficits that limit growth despite adequate fiber intake. The progressive increase in supplement consumption during the second period (+4.04 kg/day, P < 0.0001) reflects both physiological adaptation to the concentrate-based ration and improved rumen fill dynamics, as the supplemented diet reduced the bulkiness associated with exclusive grazing of mature Panicum maximum. The inverse relationship between ambient temperature and intake (r = −0.82, P < 0.001) further suggests that heat stress in the Ecuadorian Amazon may modulate voluntary intake, making controlled, energy-dense supplementation even more critical for maintaining growth during peak thermal load periods.

The improved FCR in supplemented animals underscores more efficient nutrient utilization. While grazing-only heifers likely partitioned a greater proportion of ingested energy toward maintenance, thermoregulation, and inefficient fiber digestion, supplemented animals shifted nutrients toward lean tissue accretion, as reflected in the higher ADG. This aligns with findings from tropical beef systems where strategic supplementation reduces the metabolic cost of forage digestion and improves the efficiency of gain (Moore et al., 1999; Auldist et al., 2013). It is important to contextualize these results within the broader literature: while some studies in dairy or temperate systems report similar supplementation responses, the magnitude of improvement observed here is specific to the nutritional constraints of Amazonian pastures and the physiological resilience of Brahman cattle. References to species- or system-specific studies (e.g., small ruminant forage evaluations or silvopastoral emission mitigation) were noted but are less directly applicable to the metabolic pathways governing growth in tropical beef heifers and have been deprioritized in this interpretation.

Although the live weight of the animals in this study demonstrated no variation when comparing grazing vs. supplementation (366 ± 129 kg; P = 0.69), a numerical difference of -17 kg would indicate a substantial increase in live weight when a nutritional strategy is applied in the province of Orellana. The lack of statistical significance in live weight should not diminish the practical relevance of the findings. In extensive grazing systems of the Ecuadorian Amazon, where production cycles often exceed 30 months due to low daily gains, tripling ADG through targeted supplementation can reduce time to market weight by 40–50%, directly improving farm profitability and reducing pressure on fragile ecosystems. Moreover, the use of locally available by-products (palm sludge, molasses) within a circular economy framework minimizes feed import dependency and environmental footprint, aligning with sustainable intensification goals (Rudel et al., 2015; Huera-Lucero et al., 2020). A further study reported no changes in the live weight of the animals during the experimental phase, despite applying six different supplementation strategies (Auldist et al., 2013). Similarly de Moura et al. (2020) and Pascual (2011) observed no significant changes in body condition score in five consecutive studies with dairy cows.

One of the most complex parameters in animal production is estimating voluntary feed intake under grazing conditions (Lean et al., 2014). Although numerous equations have been developed and indirect methods, have been used, these have often resulted in inaccurate predictions (Lean et al., 2014; Allen, 1996; Hassoun et al., 2016). Therefore, in this study, animals receiving supplementation were considered to have a grazing regime of no more than 20 hours per day to estimate supplement intake in the barn. The results yielded a marked difference between periods (P < 0.001). In this case, intake was 17% higher in the second period than in the first, which could have been partly influenced by environmental conditions (ambient temperature, r = -0.82; P < 0.001). In contrast to these findings, clear differences were reported regarding the average daily weight gain of the animals depending on the feeding strategy. Ruminants fed 100% pasture had a daily weight gain of 0.48 kg compared to 1.46 kg for the group that received a supplemented diet. A study by Moore et al. (1999) in which different amounts of supplements were applied (ranging from <0.2 to >40 kg/day), obtained similar data to ours (1.46 kg/day weight gain) when the animals had consumed ≥20 kg/day.

In contrast, Barbero et al. (2015) observed that animals on pasture without supplementation realized lower average daily weight gains than the present study (0.299 vs. 0.48 kg/day). On the other hand, an intriguing study by de Moura et al. (2020) in primiparous cows reported greater weight gain when supplemented daily compared to free grazing (0.54 vs. 0.35 kg/day). Consequently, as stated by Moore et al. (1999), there is a strong association between supplementation and average daily weight gain. In this regard, extensive scientific evidence has already reported in dairy cows that as supplementation increases, production levels rise (Auldist et al., 2013). These results demonstrate that supplemented animals achieved better feed conversion compared to grazing animals (8 vs. 10). While the data indicate a better feed conversion ratio in the second period (8 vs. 10), a literature review by Auldist et al. (2013) demonstrates improved feed efficiency in animals consuming less feed. However, we agree with the same author, who states that factors such as breed and environmental conditions could directly influence these responses. Based on this background, as evidenced in this study, strategic nutritional supplementation that covers basal and production requirements in ruminants is a viable option for the livestock system implemented in the study area (Auldist et al., 2013; Krysl and Hess, 1993; Da Silva et al., 2013). Furthermore, the current research incorporated local resources as a supplement, minimizing the environmental impact within a circular economy framework (Moore et al., 1999).

6. Conclusion

This study provides original, context-specific evidence that strategic nutritional supplementation significantly enhances the productive performance of Brahman heifers grazing low-quality Panicum maximum pastures in the Ecuadorian Amazon. Although final live weight did not differ significantly between treatments over the 60-day experimental period a finding consistent with the short duration and inherent variability of grazing studies the supplemented group achieved nearly threefold higher average daily gain (1.46 vs. 0.48 kg/day), demonstrating a clear biological and economic advantage.

Acknowledgements

Our sincere thanks to Jonathan Balzacar for facilitating this research.

Data Availability Statement

Upon request to the lead author.

References

• ALLEN, M.S., 1996. Physical constraints on voluntary intake of forages by ruminants. Journal of Animal Science, vol. 74, no. 12, pp. 3063-3075. https://doi.org/10.2527/1996.74123063x PMid:8994921.
  » https://doi.org/10.2527/1996.74123063x
• AULDIST, M.J., MARETT, L.C., GREENWOOD, J.S., HANNAH, M., JACOBS, J.L. and WALES, W.J., 2013. Effects of different strategies for feeding supplements on milk production responses in cows grazing a restricted pasture allowance. Journal of Dairy Science, vol. 96, no. 2, pp. 1218-1231. https://doi.org/10.3168/jds.2012-6079 PMid:23219117.
  » https://doi.org/10.3168/jds.2012-6079
• BARBERO, R.P., MALHEIROS, E.B., ARAÚJO, T.L.R., NAVE, R.L.G., MULLINIKS, J.T., BERCHIELLI, T.T., RUGGIERI, A.C. and REIS, R.A., 2015. Combining Marandu grass grazing height and supplementation level to optimize growth and productivity of yearling bulls. Animal Feed Science and Technology, vol. 209, pp. 110-118. https://doi.org/10.1016/j.anifeedsci.2015.09.010
  » https://doi.org/10.1016/j.anifeedsci.2015.09.010
• BAUMONT, R., PRACHE, S., MEURET, M. and MORAND-FEHR, P., 2000. How forage characteristics influence behaviour and intake in small ruminants: A review. Livestock Production Science, vol. 64, no. 1, pp. 15-28. https://doi.org/10.1016/S0301-6226(00)00172-X
  » https://doi.org/10.1016/S0301-6226(00)00172-X
• BEAUCHEMIN, K.A., UNGERFELD, E.M., ABDALLA, A.L., ALVAREZ, C., ARNDT, C., BECQUET, P., BENCHAAR, C., BERNDT, A., MAURICIO, R.M., MCALLISTER, T.A., OYHANTÇABAL, W., SALAMI, S.A., SHALLOO, L., SUN, Y., TRICARICO, J., UWIZEYE, A., DE CAMILLIS, C., BERNOUX, M., ROBINSON, T. and KEBREAB, E., 2022. Invited review: current enteric methane mitigation options. Journal of Dairy Science, vol. 105, no. 12, pp. 9297-9326. https://doi.org/10.3168/jds.2022-22091 PMid:36270879.
  » https://doi.org/10.3168/jds.2022-22091
• CHAVES, C.S., RIBEIRO, K.G., PEREIRA, O.G., DA FONSECA, D.M., CECON, P.R. and GOMIDE, C.A., 2021. Signal grass deferred pastures fertilized with nitrogen or intercropped with calopo. Agriculture, vol. 11, no. 9, pp. 804. https://doi.org/10.3390/agriculture11090804
  » https://doi.org/10.3390/agriculture11090804
• DA SILVA, S., GIMENES, F.M., SARMENTO, D.O.L., SBRISSIA, A.F., OLIVEIRA, D.E., HERNADEZ-GARAY, A. and PIRES, A.V., 2013. Grazing behaviour, herbage intake and animal performance of beef cattle heifers on marandu palisade grass subjected to intensities of continuous stocking management. Journal of Agricultural Science, vol. 151, no. 5, pp. 727-739. https://doi.org/10.1017/S0021859612000858
  » https://doi.org/10.1017/S0021859612000858
• DE MOURA, F.H., COSTA, T.C., TRECE, A.S., DE MELO, L.P., MANSO, M.R., PAULINO, M.F., RENNÓ, L.N., FONSECA, M.A., DETMANN, E., GIONBELLI, M.P. and DE SOUZA DUARTE, M., 2020. Effects of energy-protein supplementation frequency on performance of primiparous grazing beef cows during pre and postpartum. Asian-Australasian Journal of Animal Sciences, vol. 33, no. 9, pp. 1430-1443. https://doi.org/10.5713/ajas.19.0784 PMid:32106648.
  » https://doi.org/10.5713/ajas.19.0784
• DIJKSTRA, J., FORBES, J.M. and FRANCE, J., 2002. Quantitative aspects of ruminant digestion and metabolism Wallingford: CABI Publishing.
• FERGUSON, J.D., GALLIGAN, D.T. and THOMSEN, N., 1994. Principal descriptors of body condition score in holstein cows. Journal of Dairy Science, vol. 77, no. 9, pp. 2695-2703. https://doi.org/10.3168/jds.S0022-0302(94)77212-X PMid:7814740.
  » https://doi.org/10.3168/jds.S0022-0302(94)77212-X
• FLORES-COELLO, G., HERN, J., KU-VERA, J. and DIAZ, D., 2023. Intensive silvopastoral systems mitigate enteric methane emissions from cattle. Atmosphere (Basel), vol. 14, no. 5, pp. 863. https://doi.org/10.3390/atmos14050863
  » https://doi.org/10.3390/atmos14050863
• FUENTES, E., GÓMEZ, C., PIZARRO, D., ALEGRE, J., CASTILLO, M., VELA, J., HUAMAN, E. and VÁSQUEZ, H., 2022. A review of silvopastoral systems in the Peruvian Amazon region. Tropical Grasslands-Forrajes Tropicales, vol. 10, no. 2, pp. 78-88. https://doi.org/10.17138/tgft(10)78-88
  » https://doi.org/10.17138/tgft(10)78-88
• FUENTES-QUISAGUANO, O., GUAMÁN-RIVERA, S.A., ERAZO-RODRIGUEZ, F., GUACAPINA, A. and ARAGÓN-VÁSQUEZ, E., 2023. Erythrina edulis as a potential fodder alternative for improving livestock nutrition by small livestock farmers. Journal of Natural Science, Biology, and Medicine, vol. 14, pp. 24-28.
• GADPO, 2015 [viewed 12 December 2025]. Development and land management plan of the Province of Orellana [online]. Available from: https://www.gporellana.gob.ec
  » https://www.gporellana.gob.ec
• GOLDANSAZ, S.A., GUO, A.C., SAJED, T., STEELE, M.A., PLASTOW, S. and WISHART, D.S., 2017. Livestock metabolomics and the livestock metabolome: a systematic review. PLoS One, vol. 12, no. 5, pp. e0177675. https://doi.org/10.1371/journal.pone.0177675 PMid:28531195.
  » https://doi.org/10.1371/journal.pone.0177675
• GONZÁLEZ MARCILLO, R.L., CASTRO GUAMÀN, W.E., GUERRERO PINCAY, A.E., VERA ZAMBRANO, P.A., ORTIZ NAVEDA, N.R. and GUAMÀN RIVERA, S.A., 2021. Assessment of Guinea Grass Panicum maximum under silvopastoral systems in combination with two management systems in Orellana Province, Ecuador. Agriculture, vol. 11, no. 2, pp. 117. https://doi.org/10.3390/agriculture11020117
  » https://doi.org/10.3390/agriculture11020117
• GUAMÁN-RIVERA, S.A., ALBANELL, E., AJENJO, O., CASALS, R., ELHADI, A., SALAMA, A.A. and CAJA, G., 2023a. Performances and nutritional values of a new hooded barley (cv. Mochona) and a high yield triticale (cv. Titania) as hay or silage for sheep under Mediterranean conditions. Animal Feed Science and Technology, vol. 305, pp. 115784. https://doi.org/10.1016/j.anifeedsci.2023.115784
  » https://doi.org/10.1016/j.anifeedsci.2023.115784
• GUAMÁN-RIVERA, S.A., GUERRERO-PINCAY, A.E., ORTIZ-NAVEDA, N.R. and GONZÁLEZ-MARCILLO, R.L., 2023b. Prediction of the nutritional values by INRA (2018) feed evaluation system of Megathyrsus maximus subjected to different grazing strategies. Journal of Agriculture and Environment for International Development, vol. 117, no. 1, pp. 117-140. https://doi.org/10.36253/jaeid-14203
  » https://doi.org/10.36253/jaeid-14203
• HASSOUN, P., BASTIANELLI, D., FOULQUIÉ, D., BONNAL, L. and BOCQUIER, F., 2016. Polyethylene glycol marker measured with NIRS gives a reliable estimate of the rangeland intake of grazing sheep. Animal, vol. 10, no. 5, pp. 771-778. https://doi.org/10.1017/S1751731115002621 PMid:26621481.
  » https://doi.org/10.1017/S1751731115002621
• HUERA-LUCERO, T., LABRADOR-MORENO, J., BLANCO-SALAS, J. and RUIZ-TÉLLEZ, T., 2020. A framework to incorporate biological soil quality indicators into assessing the sustainability of territories in the ecuadorian amazon. Sustainability (Basel), vol. 12, no. 7, pp. 3007. https://doi.org/10.3390/su12073007
  » https://doi.org/10.3390/su12073007
• KRYSL, L.J. and HESS, B.W., 1993. Influence of supplementation on behavior of grazing cattle. Journal of Animal Science, vol. 71, no. 9, pp. 2546-2555. https://doi.org/10.2527/1993.7192546x PMid:8407667.
  » https://doi.org/10.2527/1993.7192546x
• KYRIAZAKIS, I., ARNDT, C., AUBRY, A., CHARLIER, J., EZENWA, V.O., GODBER, O.F., KROGH, M., MOSTERT, P.F., ORSEL, K., ROBINSON, M.W., RYAN, F.S., SKUCE, P.J., TAKAHASHI, T., VAN MIDDELAAR, C.E., VIGORS, S. and MORGAN, E.R., 2024. Improve animal health to reduce livestock emissions: quantifying an open goal. Proceedings. Biological Sciences, vol. 291, no. 2027, pp. 20240675. https://doi.org/10.1098/rspb.2024.0675 PMid:39045693.
  » https://doi.org/10.1098/rspb.2024.0675
• LEAN, I.J., GOLDER, H.M. and HALL, M.B., 2014. Feeding, evaluating, and controlling rumen function. The Veterinary Clinics of North America. Food Animal Practice, vol. 30, no. 3, pp. 539-575. https://doi.org/10.1016/j.cvfa.2014.07.003 PMid:25249402.
  » https://doi.org/10.1016/j.cvfa.2014.07.003
• MACHADO, J.M., ALEXANDRE, E., BARBOSA, M.R., LUIS, R., MILLS, A., ONGARATTO, F., MAIDANA, F.M. and MONTAGNER, P., 2022. Strategies to mitigate the emission of methane in pastures : enteric methane: a review. Australian Journal of Crop Science, vol. 16, no. 6, pp. 682-690. https://doi.org/10.21475/ajcs.22.16.06.p3457
  » https://doi.org/10.21475/ajcs.22.16.06.p3457
• MONTAGNINI, F., 2008. Management for sustainability and restoration of degraded pastures in the neotropics. In R.W. MYSTER, ed. Post-Agricultural Succession in the Neotropics. New York: Springer, pp. 265-295. https://doi.org/10.1007/978-0-387-33642-8_13
  » https://doi.org/10.1007/978-0-387-33642-8_13
• MOORE, J.E., BRANT, M.H., KUNKLE, W.E. and HOPKINS, D.I., 1999. Effects of supplementation on voluntary forage intake, diet digestibility, and animal performance. Journal of Animal Science, vol. 77, suppl. 2, pp. 122-135. https://doi.org/10.2527/1999.77suppl_2122x PMid:15526787.
  » https://doi.org/10.2527/1999.77suppl_2122x
• NATIONAL ACADEMIES OF SCIENCES, ENGINEERING, AND MEDICINE – NASEM. (2022). NASEM Nutrient Requirements of Dairy Cattle: Dry Cows, Calves, and Heifers Washington, DC: The National Academies Press.
• PASCUAL, J.J., 2011. The effect of two contrasting grazing managements and level of concentrate supplementation on the performance of grazing dairy cows. Animal Research, vol. 52, pp. 437-460.
• RUDEL, T.K., PAUL, B., WHITE, D., RAO, I.M., VAN DER HOEK, R., CASTRO, A., BOVAL, M., LERNER, A., SCHNEIDER, L. and PETERS, M., 2015. LivestockPlus: Forages, sustainable intensification, and food security in the tropics. Ambio, vol. 44, no. 7, pp. 685-693. https://doi.org/10.1007/s13280-015-0676-2 PMid:26121947.
  » https://doi.org/10.1007/s13280-015-0676-2

Edited by

• Editor:
  Takako Matsumura Tundisi

Publication Dates

• Publication in this collection
  27 July 2026
• Date of issue
  2026

History

• Received
  08 Dec 2025
• Accepted
  19 May 2026
• Corrected
  07 July 2026