Biological additives are frequently used in production systems with positive effects on animal feed and health (Wang et al. 2020). Rumen content is one of the pollutants with the greatest environmental effect, since it produces a large organic load in the effluents of slaughterhouses. However, it is a valuable nutrient source for animal feed, as it represents the undigested part of ruminant feed, as well as a large microbial load and rumen fermentation products (Sugiarto et al. 2014). It is suggested that it contains microorganisms such as Lactobacilli spp, Saccharomyces spp, actinomycetes and fermentable fungi (among others) that live in symbiosis in it. Therefore, it can be considered as a mixed culture of efficient microorganisms, which together with its nutritional characteristics and its great availability, enables different reuse alternatives (Cherdthong et al. 2015 and Castro et al. 2018).
One of the inconveniences that rumen content may present is its preservation or conservation, due to its great humidity. Fermentation is one of the technologies used to preserve and improve feed quality. According to Zhu et al. (2020), fermentation is a dynamic process that modifies the chemical composition and physical properties of foods. In poultry, fermented foods or products have demonstrated the potential to improve morphological and intestinal digestive function, as well as to modulate the intestinal microbial ecosystem (Hu et al. 2016 and Li et al. 2020).
Egg production has the function of preparing the bird for a long productive life. Therefore, it is necessary to develop its metabolic capacity, so that it creates sufficient reserves to sustain high egg production (Rodríguez 2021). García et al. (2016) pointed out that, during the replacement stage, an adequate development of the digestive tract and the immune system must be achieved, as well as good health. To achieve the aforementioned objectives, biological additives are frequently used with positive effects on productive, physiological and health indicators. Therefore, in this study, the effect of including dry fermented ruminal liquor (DFRL) in the diet on productive indicators of replacement laying hens was determined.
Materials and Methods
The study was developed in the poultry experimental unit of the Institute of Animal Science, located in San José de las Lajas municipality, Mayabeque province. Mean environmental temperature was 27.4 °C and relative humidity was 78 %.
Animals and diets. A total of 840 replacement White Leghorn L-33 laying hens were used, with mean initial liveweight of 36 ± 1.0 g/bird, from 1 to 126 d of age, which were randomly distributed into four treatments, with seven repetitions each and 30 animals/cage. Hens received food ad libitum in linear feeders and water at will through nipple drinkers, at a rate of three per cage. Beak trimming, lighting regimen and vaccination scheme were carried out according to regulations established in the Technological Manual, according to Godínez et al. (2013).
Diets were produced weekly and were formulated as isoproteic and isoenergetic, according to the recommendations cited in the Technological Manual (Godínez et al. 2013) for this poultry category. The experimental treatments were formed from the inclusion of 0 (control), 1, 2 and 3 % of DFRL in the diets, according to the growth phases: start (1 to 42 d of age) (table 1), growth (43-84 d of age) (table 2), development (85 to 112 d of age) (table 3) and pre-laying (113-126 d of age) (table 4).
Ingredients | DFRL inclusion levels, % | |||
---|---|---|---|---|
0 | 1 | 2 | 3 | |
Corn meal | 54.75 | 53.26 | 51.55 | 49.87 |
Soybean meal, 44 % CP | 38.41 | 38.45 | 38.54 | 38.63 |
DFRL | 0 | 1.00 | 2.00 | 3.00 |
Plant oil | 1.40 | 1.87 | 2.50 | 3.12 |
Monocalcium phosphate | 1.71 | 1.71 | 1.71 | 1.68 |
Calcium carbonate | 1.74 | 1.72 | 1.71 | 1.70 |
Salt | 0.38 | 0.38 | 0.38 | 0.38 |
DL- methionine | 0.23 | 0.23 | 0.23 | 0.23 |
L- lysine | 0.25 | 0.25 | 0.25 | 0.25 |
Choline chlorite | 0.13 | 0.13 | 0.13 | 0.13 |
Mineral and vitamin premix* | 1.00 | 1.00 | 1.00 | 1.00 |
CP | 21.00 | 21.00 | 21.00 | 21.00 |
ME, MJ/kg | 12.17 | 12.13 | 12.13 | 12.13 |
CF | 3.00 | 2.98 | 2.97 | 2.95 |
Calcium | 1.05 | 1.05 | 1.05 | 1.05 |
Phosphorus | 0.48 | 0.48 | 0.48 | 0.48 |
L-lysine | 1.20 | 1.20 | 1.20 | 1.20 |
DL-methionine | 0.80 | 0.79 | 0.80 | 0.80 |
DFRL: dry fermented rumen liquor*Vitamin supplement: vit. A 12,000 IU; vit. D3 2,500 IU; vit. E 40 mg; vit. K 2.1 mg; thiamine 2.5 mg, riboflavin 6.0 mg, pyridoxine 5.0 mg, vit. B12 0.020 mg, nicotinic acid 35 mg, pantothenic acid 12 mg, folic acid 1 mg, biotin 0.25 mgMineral supplement: selenium 0.2 mg, iron 60 mg, copper 8 mg, zinc 70 mg, manganese 80 mg, iodine 0.80 mg, cobalt 0.5 mg
Ingredients | DFRL inclusion levels, % | |||
---|---|---|---|---|
0 | 1 | 2 | 3 | |
Corn meal | 53.42 | 51.50 | 50.34 | 48.90 |
Soybean meal, 44 % CP | 29.50 | 29.72 | 29.75 | 29.78 |
Wheat bran | 10.00 | 10.00 | 10.00 | 10.00 |
DFRL | 0 | 1.00 | 2.00 | 3.00 |
Plant oil | 2.00 | 2.70 | 2.90 | 3.35 |
Monocalcium phosphate | 1.50 | 1.50 | 1.43 | 1.43 |
Calcium carbonate | 1.72 | 1.72 | 1.71 | 1.70 |
Salt | 0.35 | 0.38 | 0.38 | 0.38 |
DL- methionine | 0.18 | 0.23 | 0.23 | 0.23 |
L- lysine | 0.20 | 0.25 | 0.25 | 0.25 |
Choline chlorite | 0.13 | 0.13 | 0.13 | 0.13 |
Mineral and vitamin premix* | 1.00 | 1.00 | 1.00 | 1.00 |
CP | 18.50 | 18.50 | 18.50 | 18.50 |
ME, MJ/kg | 11.92 | 11.92 | 11.92 | 11.92 |
CF | 3.48 | 3.48 | 3.48 | 3.45 |
Calcium | 1.05 | 1.05 | 1.05 | 1.00 |
Phosphorus | 0.48 | 0.48 | 0.48 | 0.45 |
L-lysine | 1.20 | 1.20 | 1.20 | 1.20 |
DL-methionine | 0.80 | 0.79 | 0.80 | 0.80 |
DFRL: dry fermented rumen liquor*Vitamin supplement: vit. A 8,500 IU; vit. D3 2,000 IU; vit. E 10 mg; vit. K 2.1 mg; thiamine 1.5 mg, riboflavin 4.0 mg, pyridoxine 3.0 mg, vit. B12 0.010 mg, nicotinic acid 30 mg, pantothenic acid 10 mg, folic acid 0.6 mg, biotin 0.10 mgMineral supplement: selenium 0.2 mg, iron 60 mg, copper 8 mg, zinc 70 mg, manganese 80 mg, iodine 0.80 mg, cobalt 0.5 mg
Ingredients | DFRL inclusion levels, % | |||
---|---|---|---|---|
0 | 1 | 2 | 3 | |
Corn meal | 57.86 | 58.00 | 56.98 | 56.26 |
Soybean meal, 44 % CP | 17.00 | 17.37 | 17.10 | 17.27 |
Wheat bran | 18.50 | 17.00 | 17.00 | 16.30 |
DFRL | 0 | 1.00 | 2.00 | 3.00 |
Plant oil | 1.50 | 1.50 | 1.85 | 2,10 |
Monocalcium phosphate | 1.45 | 1.45 | 1.45 | 1.45 |
Calcium carbonate | 1.92 | 1.92 | 1.85 | 1.85 |
Salt | 0.35 | 0.35 | 0.35 | 0.35 |
DL- methionine | 0.17 | 0.17 | 0.17 | 0.17 |
L- lysine | 0.12 | 0.11 | 0.12 | 0.12 |
Choline chlorite | 0.13 | 0.13 | 0.13 | 0.13 |
Mineral and vitamin premix* | 1.00 | 1.00 | 1.00 | 1.00 |
| ||||
CP | 14.56 | 14.59 | 14.50 | 14.50 |
ME, MJ/kg | 11.51 | 11.51 | 11.51 | 11.51 |
CF | 3.75 | 3.63 | 3.60 | 3.53 |
Calcium | 1.05 | 1.05 | 1.05 | 1.05 |
Phosphorus | 0.45 | 0.45 | 0.45 | 0.45 |
L-lysine | 0.67 | 0.67 | 0.67 | 0.67 |
DL-methionine | 0.57 | 0.57 | 0.57 | 0.57 |
DFRL: dry fermented rumen liquor *Vitamin supplement: vit. A 8,500 IU; vit. D3 2,000 IU; vit. E 10 mg; vit. K 2.1 mg; thiamine 1.5 mg, riboflavin 4.0 mg, pyridoxine 3.0 mg, vit. B12 0.010 mg, nicotinic acid 30 mg, pantothenic acid 10 mg, folic acid 0.6 mg, biotin 0.10 mg Mineral supplement: selenium 0.2 mg, iron 60 mg, copper 8 mg, zinc 70 mg, manganese 80 mg, iodine 0.80 mg, cobalt 0.5 mg |
Ingredients | DFRL inclusion levels, % | |||
---|---|---|---|---|
0 | 1 | 2 | 3 | |
Corn meal | 61.86 | 60.90 | 56.98 | 56.26 |
Soybean meal, 44 % CP | 25.90 | 26.25 | 17.10 | 17.27 |
Wheat bran | 5.00 | 4.00 | 5.00 | 5.00 |
DFRL | 0 | 1.00 | 2.00 | 3.00 |
Plant oil | 0 | 0.50 | ||
Monocalcium phosphate | 1.54 | 1.54 | 1.45 | 1.45 |
Calcium carbonate | 4.35 | 4.33 | 1.85 | 1.85 |
Salt | 0.25 | 0.25 | 0.35 | 0.35 |
DL- methionine | 0.10 | 0.10 | 0.17 | 0.17 |
Choline chlorite | 0.13 | 0.13 | 0.13 | 0.13 |
Mineral and vitamin premix* | 1.00 | 1.00 | 1.00 | 1.00 |
CP | 16.96 | 17.05 | 16.81 | 16.88 |
ME, MJ/kg | 11.63 | 11.64 | 11.63 | 11.63 |
CF | 2.87 | 2.80 | 2.75 | 2.65 |
Calcium | 2.00 | 2.00 | 2.00 | 2.00 |
Phosphorus | 0.45 | 0.44 | 0.44 | 0.44 |
L-lysine | 0.86 | 0.86 | 0.84 | 0.85 |
DL-methionine | 0.61 | 0.61 | 0.60 | 0.60 |
DFRL: dry fermented rumen liquor *Vitamin supplement: vit. A 8,500 IU; vit. D3 2,000 IU; vit. E 10 mg; vit. K 2.1 mg; thiamine 1.5 mg, riboflavin 4.0 mg, pyridoxine 3.0 mg, vit. B12 0.010 mg, nicotinic acid 30 mg, pantothenic acid 10 mg, folic acid 0.6 mg, biotin 0.10 mg Mineral supplement: selenium 0.2 mg, iron 60 mg, copper 8 mg, zinc 70 mg, manganese 80 mg, iodine 0.80 mg, cobalt 0.5 mg |
A single batch of the product was produced in the Food Production Laboratory of the Institute of Animal Science, as described by Savón et al. (2020). For diet formulation, the bromatological composition of the DFRL was considered: 88.90 % of dry matter (DM), 9.25 % of crude protein (CP), 0.49 % of crude fiber (FB), 0.35 % of total phosphorus (tP) and 0.48 % of calcium (Ca).
Productive indicators. Productive performance was determined according to growth stages (42, 84 and 126 d of age): feed intake by the offer and rejection method, liveweight on a technical scale (SARTORIUS, Germany), with ± 0.10 g precision and feed conversion (kg/kg liveweight gain). Deaths were daily controlled, which allowed to find the viability in each stage. For uniformity, the individual liveweight of 21 birds/treatment was used for each rearing stage. At the end, 10 hens per treatment were sacrificed to evaluate ovary and oviduct development. Oviduct length and weight data, as well as ovary weight, were taken, which allowed calculating these indicators relative to liveweight.
Statistical methods. The theoretical assumptions of the analysis of variance and normality of errors were verified based on Shapiro and Wilk (1965) test and by homogeneity of variance, according to Levene (1960) test for the viability variable. As the theoretical assumptions of ANAVA were not met, the arcsine √ % transformation was used. However, the latter did not improve compliance with these assumptions, so a non-parametric Kruskal Wallis analysis of variance was performed. Conover (1999) test was applied for the comparison of mean ranges.
For the productive indicators feed intake, liveweight, feed conversion, oviduct relative length, relative weights of oviduct and ovary, analysis of variance was performed, according to a completely randomized design. Mean values were compared using Duncan (1955) test in the necessary cases. For batch uniformity, descriptive statistics (mean, standard deviation, coefficient of variation, and confidence intervals) was applied. For data analysis, the statistical package Infostat (Di Rienzo et al. 2012) was used.
Results and Discussion
Table 5 shows that viability of replacement layers was greater than 96 %, demonstrating that DFRL had no negative effects on poultry health. The product did not influence on feed intake. However, at 84 d of age, feed conversion improved (P=0.0003) compared to the group in which it was not included. Meanwhile, in general rearing (1-126 d of age), no differences were found for this indicator among the groups with DFRL. The group with 2 % differed (P=0.0245) from those that did not receive the product (4.51 vs. 4.76, respectively).
Productive indicators | DFRL inclusion levels, % | SE (±) | P | |||
---|---|---|---|---|---|---|
0 | 1 | 2 | 3 | |||
General viability, % | 9.64 (96.66) SD =2.72 |
17.79 (99.51) SD =1.26 |
16.86 (98.56) SD =3.78 |
13.71 (98.09) SD =2.62 |
0.1220 | |
Feed intake, kg/hen 1-42 d of age 43-84 d of age 85-126 d of age 1-126 d of age |
||||||
Feed conversion, kg/kg 1-42 d of age 43-84 d of age 85-126 d of age 1-126 d of age |
2.42 1.98a 2.29 4.76a |
2.48 1.88b 2.24 4.63ab |
2.42 1.88b 2.18 4.51b |
2.45 1.86b 2.23 4.60ab |
0.04 0.02 0.03 0.05 |
0.5168 0.0003 0.0511 0.0245 |
Liveweight, g/hen 42 d of age 84 d of age 126 d of age |
458 1162a 1349a |
445 1215b 1385ab |
450 1215b 1419b |
452 1219b 1395ab |
5.63 9.69 15.85 |
0.4534 0.0008 0.0360 |
a,b Different letters in the same line differ at P < 0.05 DFRL: dry fermented ruminal liquor SD: standard deviation () means from original data |
Results correspond to those of Savón et al. (2020), who found greater elongation of villi of the mucus of the small intestine and hyperplasia of cecal tonsils in broilers that consumed DFRL, which could indicate better absorption of nutrients and possible immunostimulatory effect. Similarly, DFRL, due to its richness in Lactobacillus, yeasts, organic acids with short carbonated chains and low pH, could stabilize the flora of the gastrointestinal tract and increase digestibility of dry matter and cell wall (Castro et al. 2018).
Several studies point out the beneficial effect of fermentation and lactic acid bacteria on indicators of productive performance. Authors such as Chiang et al. (2010), Missotten et al. (2013) and Sugiharto and Ranjitkar (2019) suggested that fermented products can increase the length of the small intestine to maintain the normal microbial ecosystem and improve intestinal morphology. This makes it possible to increase digestion and absorption, which translates into a better productive performance. Wu et al. (2019) found, with the use of Lactobacillus, an increase of these microorganisms in the intestine, a higher serum concentration of immunoglobulins, as well as a decrease of Escherichia coli and pH in the ileum and cecum, which favors poultry health.
Liveweight of hens, at 84 d of age, was similar in the treatments with DFRL and superior to control group (P=0.0008). However, at 126 d of age, this indicator remained similar among experimental treatments, and only 2 % was higher (P=0.0360) than the group without the product (1419 vs. 1349 g/bird, respectively). The previous is related to the best feed conversion achieved in the treatments with the product, and allowed the good body development of the animals. This is important, since the growth stage is the one with the greatest weight gain during rearing. In this period, the birds develop 90 % of their bone structure (Grandía et al. 2016), which will allow having a bird that has body reserves for laying.
At 126 d of age, regardless of the treatment, animals reached a liveweight higher than that established for this line (1,300 g/bird). This aspect should be considered for future studies, since some authors refer that overweight hens can determine lower yields in layers than those that arrive with the appropriate weight. This, in turn, means lower egg shell thickness, inferior persistence in production and greater death risk due to prolapse of the oviduct (Callejo 2011 and Martínez et al. 2013). Although García et al. (2016), when studying the effect of body weight on bioproductive indicators in White Leghorn L33 hens, found differences between production, weight and size of eggs for the group with higher body weight, higher internal egg quality (white and yolk height) was confirmed.
Batch uniformity in poultry rearing describes the variability in a population, and the more homogeneous it is, then it is expressed into better production (Itzá et al. 2011). Table 6 demonstrates that all liveweights, regardless of treatment and age, were found between the minimum and superior limits, determined with a variation coefficient lower than 8. According to Anon (2020), a poultry batch having a coefficient of variation lower than 6, as it happens in the present research, corresponds to a uniformity superior to 90 %, which indicates that it was good. This will allow maintaining egg production in accordance with the potential of this genetic line (Gous 2018).
DFRL inclusion levels, % | Uniformity | n | Mean liveweight | SD | CV, % | IL, 5 % | SL, 95 % |
---|---|---|---|---|---|---|---|
0 | 42 d of age | 21 | 477 | 16.04 | 3.37 | 469 | 484 |
84 d of age | 21 | 1.179 | 64.21 | 5.45 | 1.150 | 1.208 | |
126 d of age | 21 | 1.389 | 88.58 | 6.38 | 1.348 | 1.429 | |
1 | 42 d of age | 21 | 464 | 21.69 | 4.68 | 454 | 473 |
84 d of age | 21 | 1.220 | 38.06 | 3.12 | 1.203 | 1.237 | |
126 d of age | 21 | 1.465 | 38.06 | 2.60 | 1.448 | 1.482 | |
2 | 42 d of age | 21 | 458 | 17.47 | 3.82 | 450 | 466 |
84 d of age | 21 | 1.219 | 49.84 | 4.09 | 1.197 | 1.242 | |
126 d of age | 21 | 1.464 | 49.84 | 3.40 | 1.442 | 1.487 | |
3 | 42 d of age | 21 | 468 | 16.30 | 3.49 | 460 | 475 |
84 d of age | 21 | 1.227 | 58.56 | 4.77 | 1.200 | 1.253 | |
126 d of age | 21 | 1.472 | 58.56 | 3.98 | 1.445 | 1.498 |
SD: standard deviation, CV: coefficient of variation, IL: inferior limit, SL: superior limit
DFRL: dry fermented ruminal liquor
Ovary and oviduct development of hens is closely related to their body development, so it is necessary to optimize the achievement of their development for future production.
Table 7 shows values related to ovary and oviduct of replacement layers, with the inclusion of DFRL in the diet. No treatment effect was found on these reproductive tract variables. Although a higher numerical trend was observed, with 3 % of the product in the relative length of the oviduct, and also in the relative weight of the ovary, compared to the group that did not consume the product. This indicates the need to deepen into these aspects and also consider a larger sample size.