Animal Science

Growth promoting effect of a processed vegetable ingredient in pullets

0000-0003-4467-5563K. D. Coello¹  , 0000-0002-9295-0585L. A. Castellanos¹  , 0000-0002-9388-9579P. E. Paz²  , 0000-0002-8858-0307M. Valdivié³  , 0000-0003-2167-4904Y. Martínez^{1  *} 

¹Centro de Investigación y Enseñanza Avícola, Departamento de Ciencia y Producción Agropecuaria, Escuela Agrícola Panamericana, Zamorano, Honduras

²Departamento de Ciencia y Producción Agropecuaria, Escuela Agrícola Panamericana, Zamorano, Honduras

³Centro Nacional para la Producción de Animales de Laboratorio, Santiago de las Vegas, Rancho Boyeros, La Habana, Cuba

ABSTRACT

A total of 1,500 one-day-old Hy-Line W36 pullets were randomized in two treatments, 15 repetitions and 50 pullets per repetitions to evaluate the dietary use of a processed vegetable ingredient (PVI) as a functional feed on the growth performance of pullets. The dietary treatments consisted of the inclusion of 10, 8, 5, and 3 % of the processed vegetable ingredient in starter 1 (0-3 weeks), starter 2 (4-6 weeks), grower (7-12 weeks), developer and pre-lay (13-15; 16-17 weeks, respectively). From the third week on, the functional feed increased (P<0.05) the body weight of pullets compared to the control diet (193.98 vs 204.38 g), without notable changes for viability, uniformity, and feed conversion ratio for 17 experimental weeks (P>0.05). The dietary inclusion with the processed vegetable ingredient had a natural growth-promoting effect on pullets.

Key words: body weight; dietary inclusion; feed intake; functional feed; birds

Currently, the high prices of raw materials to feed birds, which represent up to 75 % of the cost of poultry production (^{Dal Bosco 2021}), have led to the generation of new ideas to counteract these current problems. Thus, one of the nutritional strategies is the development and use of functional ingredients to improve the feeding efficiency of birds (^{Fang et al. 2017} and ^{Fries-Craft et al. 2021}). It is known that functional foods provide one or more differentiated components to improve the physiological functions of the animal organism (^{Teklić et al. 2021}). Also, the poultry industry has a wide interest in the use of functional products, especially as one of the nutritional strategies to eliminate growth-promoting antibiotics in these animals and improve the quality of the final product with a direct impact on the modern consumer (^{Camacho et al. 2019}). Although most studies are conducted on fast-growing birds (broilers), the use of these feeds can also improve the growth performance of growing and developing pullets, mainly because it directly influences the development of the gastrointestinal tract and the immune response (^{Ayodele et al. 2021}).

While many functional feeds have been developed, few are derived from plant ingredients after a biotechnological process (^{Wang et al. 2021}). The processed vegetable ingredient (MrFeed^® Pro50 C) is derived from a biotechnological process without artificial preservatives, is highly digestible, and rich in metabolizable energy, proteins, essential amino acids, peptides, nucleotides, vitamins, and minerals (^{Martínez 2021}). To obtain the processed vegetable ingredient (MrFeed Pro50^® Poultry), three chemical processes are applied to an organic by-product, known as fermentation, hydrolysis, and oligomerization (^{Menon Renewable Products, Inc. 2020}).

Studies conducted with this processed vegetable ingredient as a functional feed in broilers, tilapia, and shrimp diets found better feed efficiency and gut health, mainly due to the concentration of bioactive peptides less than 500 Daltons and nucleic acids, however, the results are inconsistent in dairy cow calves and growing pigs (^{McLean et al. 2020}, ^{Ordoñez 2020} and ^{Herrera and Moreno 2020}, ^{Ponce 2021} and ^{Martínez 2021}). Thus, the processed vegetable ingredient, due to its chemical composition, could be used in slow-growing birds to promote the body weight of these birds before laying. Therefore, the aim of the present trial was to evaluate the dietary use of a processed vegetable ingredient as a functional feed on growth performance of pullets.

Materials and Methods

Experimental location. The experiment in a non-tunneled shed was developed located in the Poultry Research and Teaching Center of the Pan-American Agricultural School, Zamorano, located in the Yegüare Valley, San Antonio de Oriente, Francisco Morazán department, km 30 on the road of Tegucigalpa to Danlí, Honduras. At coordinates 1400’9 “N and 86059’31” W, 760 meters above sea level, with an average temperature of 26 °C.

Processed vegetable ingredient. The processed vegetable ingredient (MrFeed^® Pro50 C) was supplied from the company Menon Renewable Products, Inc. (Escondido, California, USA). To obtain the processed vegetable ingredient, a by-product fermentation process was developed using a microbial inoculum to increase the concentration of nucleic acids. Followed by a specific enzymatic hydrolysis considering time, temperature, pH, and enzymes to carry out transformations of physicochemical properties, its main objective was the production of peptides. The third process consisted of an oligomerization, through catalysis to accelerate this process, then these are brought together to produce the different versions of the processed vegetable ingredient (MrFeed^® Pro50 C) (^{Menon Renewable Products, Inc. 2020}). According to Menon Renewable Products, this processed vegetable ingredient (MrFeed^® Pro50 C) has 51.9 % protein, 4.47 % lysine, 1.68 % methionine + cystine, 1.82 % threonine, 2.07 % valine and 19.49 MJ/kg of true metabolizable energy (^{Menon Renewable Products, Inc. 2020}).

Animals, experimental design, and treatments. A total of 1,500 one-day-old Hy-Line W36 pullets were randomized in two treatments, 15 repetitions and 50 pullets per repetition. The dietary treatments consisted of: Starter 1 (0-3 weeks): control (0 %) and 10 % the processed vegetable ingredient (PVI); Starter 2 (4-6 weeks): control (0 %) and 8 % PVI; Grower (7-12 weeks): control (0 %) and 5 % PVI; Development (13-15 weeks): control (0 %) and 3 % PVI; Pre-lay (16-17 weeks): control (0 %) and 3 % PVI according to the recommendations of ^{Menon Renewable Products, Inc. (2020)}. The experimental diets are presented in table 1.

Table 1 Ingredients and contributions of basal diets (control treatment) and diets with inclusion levels of a processed vegetable ingredient 

	Starter 1		Starter 2		Grower		Developer		Pre-lay
Ingredients (%)	Basal diet	PVI	Basal diet	PVI	Basal diet	PVI	Basal diet	PVI	Basal diet	PVI
Corn meal	59.382	61.891	62.566	64.681	61.639	63.818	63.706	64.696	59.252	60.05
Soybean meal	33.706	22.324	28.658	19.687	27.891	20.343	22.482	18.409	24.566	21.098
Wheat bran	00.00	00.00	02.11	01.966	05.168	05.752	08.115	8.335	5.782	05.774
PVI	00.00	10.00	00.00	08.00	00.00	05.00	00.00	3.00	0.00	03.00
Palm oil	02.23	01.69	02.00	01.54	00.00	00.00	00.00	0.00	1.96	01.80
CaCo3	01.69	01.247	01.709	01.355	01.741	01.517	01.772	1.638	5.775	05.643
Molasses	00.00	00.00	00.00	00.00	01.00	01.00	01.50	1.50	0.00	00.00
Biofos	01.658	01.679	01.591	01.608	01.436	01.446	01.306	1.312	01.522	01.529
Sodium chloride	00.268	00.299	00.228	00.277	00.239	00.24	00.237	0.238	00.291	00.292
Sodium bicarbonate	00.248	00.206	00.262	00.198	00.245	00.243	00.28	0.279	00.215	00.213
Premixes	00.23	00.23	00.23	00.23	00.23	00.23	00.23	0.23	00.23	00.23
DL-methionine	00.211	00.161	00.194	00.153	00.164	00.148	00.129	0.118	00.158	00.143
Mycofix plus 5.0	00.15	00.15	00.15	00.15	00.15	00.15	00.15	0.15	00.15	00.15
L- treonine	00.086	00.059	00.106	00.083	00.034	00.049	00.029	0.031	00.035	00.029
L-lysine	00.078	00.00	00.131	00.004	00.00	00.00	00.00	0.00	00.00	00.00
L-tryptophan	00.00	00.00	00.00	00.005	00.00	00.00	00.00	0.00	00.00	00.005
Coccidiostat	00.05	00.05	00.05	00.05	00.05	00.05	00.05	0.05	00.05	00.05
Phytase	00.01	00.01	00.01	00.01	00.01	00.01	00.01	0.01	00.01	00.01
Zn Bacitracin	00.004	00.004	00.004	00.004	00.004	00.004	00.004	0.004	00.004	00.004
Nutritional contributions (%)
ME (MJ/kg)	12.46	12.46	12.46	12.46	12.26	12.26	12.05	12.05	12.05	12.05
Crude protein	20.00	20.00	18.25	18.25	17.50	17.50	16.00	16.00	16.50	16.50
Ca	01.05	01.05	01.00	01.00	00.95	00.95	00.90	0.90	02.50	2.50
Available phosphorus	00.48	00.48	00.47	00.47	00.45	00.45	00.40	0.40	00.43	0.43
Lysine	01.05	01.05	00.98	00.98	00.88	00.88	00.76	0.76	00.78	0.78
Methionine+cystine	00.74	00.74	00.74	00.74	00.67	00.67	00.59	0.59	00.66	0.66
Treonine	00.69	00.69	00.66	00.66	00.60	00.60	00.52	0.52	00.55	0.55

¹Each kg contains: vitamin A 11,550 IU, vitamin D₃ 4,300 IU, vitamin E 27.5 IU, vitamin K₃ 3.85 mg, vitamin B₁ 2.75 mg, vitamin B₂ 9.9 mg, vitamin B₆ 3.85 mg, vitamin B₁₂ 22.0 Mcg, niacin 49.5 mg, pantothenic acid 15.4 mg, folic acid 1.38 mg, biotin 166 Mcg; selenium 0.09 mg, iodine 0.18 mg, copper 3.00 mg, iron 36.0 mg, manganese 54.0 mg, zinc 48.0 mg, cobalt 0.12 mg.

Experimental conditions. The pullets were housed in a 400 m2 commercial shed and in 1.6 × 3.7 m cages with ceiling fans and an artificial lighting system. Each 5.92 m2 cage (1.6 m front × 3.7 m deep), housed 50 pullets/pen and 8.78 pullets/m2. Water and feed were offered ad libitum in troughs and bell feeders. sixteen hours of light were provided each day and the wood chips were used as poultry litter, also, the temperature and relative humidity within the shed were controlled. Pre-experimental adaptation to the new diets was intentionally not used.

Growth performance. The indicators of the performance of the pullets were determined weekly. Viability was determined by live animals among those existing at the beginning of the experiment. Body weight was performed individually, on a Mettler Toledo^® IND226 industrial scale with precision ± 1.00 g. Feed intake was calculated weekly using the offer and reject method. For the feed conversion ratio per week, the accumulated feed intake and the weight gain were considered. Uniformity was carried out in the period (0-17 weeks) according to the method ±10.

Experimental design and statistical analysis. The data were analyzed using the Student’s t test, according to a completely randomized design. Previously, the normality of the data was verified by the Kolmogorov-Smirnov test and the uniformity of the variance by the Bartlett test. The viability was determined by comparison of proportions. IBM^® SPSS^® Statistics version 23.0.1.2014 was used.

Results and Discussion

Table 2 shows the effect of PVI as part of the diet on growth performance of Hy-Line W36 replacement layer pullets over 17 weeks. In the first two weeks old, no significant differences were found between treatments (P>0.05). However, from the third week, body weight increased (P<0.05) due to PVI diets, although with no notable changes in feed intake and viability (P>0.05).

Table 2 Effect of the inclusion in the diet of a processed vegetable ingredient on the growth of pullets in the starter 1 phase (1-3 weeks) 

Items	Experimental treatments		SEM±	P-value
	Control	Processed vegetable ingredient
Week 1
Initial body weight (g)	35.02	34.95	0.197	0.813
Final body weight (g)	74.13	75.89	0.754	0.113
Feed intake (g)	95.32	95.70	1.910	0.888
Viability (%)	99.33	99.42	0.335	0.862
Feed conversion ratio	2.44	2.34	0.048	0.059
Week 2
Body weight (g)	115.51	115.08	0.570	0.596
Feed intake (g)	96.08	99.27	1.750	0.211
Viability (%)	98.92	98.50	0.584	0.619
Feed conversion ratio	2.32	2.53	0.079	0.052
Week 3
Body weight (g)	193.98	204.38	2.293	0.004
Feed intake (g)	226.46	216.92	6.060	0.278
Viability (%)	99.67	99.42	0.272	0.523
Feed conversion ratio	2.89	2.42	0.091	0.038

It is known that the first week old of laying pullets is the most critical stage, since physiologically they cannot regulate their body temperature and have an immature digestive and immune system, thus the viability (99.33 to 99.42 %) in this experiment it was excellent. Furthermore, these results agree with ^{Jung and Batal (2012)} who found no significant changes in feed intake when they used nucleotide diets in the first 10 days old. PVI does not appear to cause any harm when used up to 10 % inclusion in diets. Other studies with the processed vegetable product in broilers, pigs, tilapia, shrimp, and dairy cows reported similar results in viability (^{McLean et al. 2020}, ^{Herrera and Moreno 2020}, ^{Ponce 2021} and ^{Martínez 2021}).

From week 3 this functional product (PVI) promoted the body weight of the pullets (table 2), which could justify its use in poultry feed at all production scales. This processed vegetable product has 4800 mg/kg of nucleotides, the most quantified being cyclic adenosine monophosphate (AMPs), cyclic guanosine monophosphate (GMP) and uridine diphosphate (UDP) (^{Menon Renewable Products, Inc. 2020}). The positive effects observed with PVI could be because the nucleotides participate in the rapid cell proliferation and in the antioxidant activity of the organism, especially in young pullets due to the stress factors that affect the animals (^{Świątkiewicz et al. 2014}). In this sense, ^{Esteve-García et al. (2007)} found a better productive response in the third week (21 days) of life in broilers when they used a diet based on nucleotides as additives (500 mg/kg). However, these authors did not find a productive efficacy when they used up to 1 g/kg, which shows that an excess of nucleotides can have a negative effect.

Likewise, ^{Nazeer et al. (2021)} have reported with peptides to have antimicrobial and immunomodulatory activities in the gastrointestinal (GI) tract of avian species. According to ^{Menon Renewable Products, Inc. (2020)} this processed vegetable ingredient shows that of the total quantified peptides, 48 % have a low molecular weight between 25 to 30 kDA more than soymeal and fishmeal. Although there are contradictions if the molecular weight of peptides has a direct influence on gut health, it seems that this should also be associated with the type of peptides in poultry diets. Therefore, feed products rich in beta defensin as a low molecular weight microbial peptide in poultry diets have been shown to enhance the immune system, being expressed in leukocytes and epithelial cells (^{Jacob and Pescatore 2014}). Also, more studies are needed to understand the exact concentrations of nucleotides and peptides in the diet, but it seems that PVI promotes the greatest contributions of these in the diets. These results could be the starting point to understanding the role of nucleotides in feeds and their contributions to diets.

Table 3 shows the effect of PVI on performance of laying pullets in the start phase 2. Body weight improved (P<0.05) with the use of functional feed (PVI), also this product decreased feed conversion ratio in weeks 4 and 5, without changes in feed intake and viability (P>0.05).

Table 3 Effect of dietary inclusion with a processed vegetable ingredient on growth performance of pullets in the starter 2 phase (4-6 weeks) 

Items	Experimental treatments		SEM±	P-value
	Control	Processed vegetable ingredient
Week 4
Body weight (g)	252.34	279.37	2.956	<0.001
Feed intake (g)	226.63	219.62	8.277	0.556
Viability (%)	99.17	97.92	0.775	0.266
Feed conversion ratio	3.88	2.93	0.128	0.008
Week 5
Body weight (g)	324.23	365.89	1.689	<0.001
Feed intake (g)	204.66	217.67	8.499	0.291
Viability (%)	99.50	99.42	0.325	0.858
Feed conversion ratio	2.85	2.52	0.112	0.052
Week 6
Body weight (g)	373.27	401.95	5.150	0.001
Feed intake (g)	298.71	298.75	11.302	0.708
Viability (%)	99.42	98.08	0.818	0.359
Feed conversion ratio	6.09	8.28	0.524	0.050

Pullet body weight increased by 27 and 28 g at weeks 4-5 on the PVI diets, respectively. It should be noted that the pullets have a weight similar to that reported by the genetic line, except in week 6 that the pullets of the control group had 93.02 % of the standard weight. Other authors such as ^{Karimzadeh et al. (2016)} found an increase in body weight in broilers when they used diets with peptides for the period of 29-42 days. Furthermore, ^{Jung and Batal (2012)} reported that nucleotide-based diets promoted weight gain compared to the control diet. ^{Wu et al. (2018)} found that dietary inclusion with nucleotides increased the villi height of the gastrointestinal tract, which improved intestinal health. According to ^{Wang et al. (2022)} a rapid development of the intestinal mucosa increases the villi height, which improves the use of nutrients from an early age and in turn the development and growth.

In a study in broilers, this PVI markedly changed villus height (VH) and crypt depth (CD), relative to the basal diet. Also, in the duodenum and ileum, this alternative treatment (PVI) increased the VH:CD ratio (^{Martínez 2021}). The ratio among villi and crypts is useful to estimate the digestion of nutrients and the absorptive capacity of the small intestine, a higher villus/crypt ratio translates into greater efficiency in the digestive process (^{Singh and Kim 2021}). In this sense, ^{Ebeid et al. (2021)} reported that crypt and villus morphology is associated with intestinal health and growth in animals. Authors such as ^{Dixon et al. (2022)} informed a direct relationship between the villi height and the absorption of nutrients, which promotes growth, this effect seems to have occurred in this experiment, however further research is needed to justify this hypothesis.

The dietary inclusion with PVI promoted (P<0.05) the body weight of laying pullets in the productive phase of grower (7-12 weeks), however, at week 12, this functional product (PVI) increased feed conversion ratio (P<0.05). The other indicators did not change due to the effect of the experimental diets (table 4).

Table 4 Effect of dietary inclusion with a processed vegetable ingredient on growth performance of pullets in the grower phase (7-12 weeks) 

Items	Experimental treatments		SEM±	P-value
	Control	Processed vegetable ingredient
Week 7
Body weight (g)	470.96	503.19	5.699	0.001
Feed intake (g)	309.93	319.02	20.858	0.761
Viability (%)	100.00	100.00
Feed conversion ratio	3.17	3.15	0.018	0.083
Week 8
Body weight (g)	571.68	602.98	6.725	0.003
Feed intake (g)	518.80	502.04	10.105	0.253
Viability (%)	99.17	98.83	0.582	0.689
Feed conversion ratio	5.15	5.03	0.048	0.058
Week 9
Body weight (g)	646.94	681.54	6.721	0.001
Feed intake (g)	560.14	558.40	19.033	0.949
Viability (%)	98.17	98.75	0.769	0.597
Feed conversion ratio	7.44	7.11	0.134	0.062
Week 10
Body weight (g)	711.98	746.47	5.600	0.001
Feed intake (g)	498.35	502.72	10.930	0.780
Viability (%)	99.50	99.50	0.261	0.999
Feed conversion ratio	7.66	7.74	0.038	0.071
Week 11
Body weight (g)	805.72	844.72	7.098	0.001
Feed intake (g)	567.73	613.20	18.083	0.089
Viability (%)	99.50	98.92	0.337	0.233
Feed conversion ratio	6.06	6.24	0.079	0.086
Week 12
Body weight (g)	870.27	905.75	9.176	0.012
Feed intake (g)	559.47	580.52	15.691	0.353
Viability (%)	99.42	99.75	0.283	0.414
Feed conversion ratio	8.67	9.51	0.249	0.048

As well, at week 7 it is observed that body weight increased with dietary inclusion with PVI in 7.02 %, and these pullets have a body weight similar as recommended the genetic line. At week 8, the use of PVI marked a difference in body weight in relation to the control in 31.3 g. ^{García et al. (2019)} informed that pullets have a high growth rate that is related to rapid early development of the gastrointestinal tract, thus the use of nucleotides and peptides could increase the intestinal health and absorption of nutrients in pullets (^{Abdollahi et al. 2017}). Also, ^{Martínez (2021)} found that the inclusion with 5 % of PVI (0 to 10 days old) for broilers promoted a greater development of the bursa of Fabricius and the spleen, which could show a stimulation of immunity (^{He et al. 2019}).

In weeks 9 and 10, it was found that the PVI modified live weight by 4.84 % in relation to the basal diet (table 4). Although no differences were observed between treatments for feed intake and viability (table 4). At week 11, it was found that the dietary use of PVI increased the body weight of the pullets by 39 g, with 97.01 % of body weight corresponding to the standard weight. These results confirm that peptide-based diets promote proper weight gain and nutrient digestibility and absorption. Studies by ^{Karimzadeh et al. (2016)} and ^{Osho et al. (2019)} found that the use of 200 and 250 mg/kg of bioactive peptides in poultry diets decreased the count of gram-negative bacteria in the ileum and caecum compared to the control group, as well as improved feed nutrients digestibility. Also, ^{Feng et al. (2007)} and ^{Landy et al. (2021)} found that the increase in growth in pullets may be due to higher enzymatic activity in the intestine due to the peptides supplemented in the ration.

At week 12, 35.48 g was observed as the difference found between treatments for these pullets when PVI were used as function feed, the pullets had 95.26 % of the ideal weight of the line. Apparently, the increase in feed conversion ratio with PVI was due to the non-significant increase in feed intake with this natural product (PVI), even though PVI increased body weight (35.48 g). In this sense, ^{Osho et al. (2019)} found an increase in gain:feed when they used peptide diets in broiler diets.

Like the other results, table 5 indicates that the PVI modifies the body weight of the pullets (P<0.05), also, at weeks 14 and 15 it increased feed intake (P<0.05), and the feed conversion ratio varied between treatments (P<0.05).

Table 5 Effect of dietary inclusion with a processed vegetable ingredient on growth performance of pullets in the development phase (13-15 weeks) 

Items	Experimental treatments		SEM±	P-value
	Control	Processed vegetable ingredient
Week 13
Body weight (g)	967.05	1019.48	8.230	<0.001
Feed intake (g)	565.97	583.48	15.919	0.445
Viability (%)	99.08	99.25	0.332	0.726
Feed conversion ratio	5.85	5.13	0.159	0.038
Week 14
Body weight (g)	1034.00	1066.38	8.535	0.015
Feed intake (g)	566.56	587.49	2.584	<0.001
Viability (%)	98.00	99.17	0.589	0.175
Feed conversion ratio	8.46	12.53	1.038	0.008
Week 15
Body weight (g)	1109.09	1148.67	9.945	0.010
Feed intake (g)	565.98	582.66	2.401	<0.001
Viability (%)	99.25	98.92	0.541	0.667
Feed conversion ratio	7.54	7.08	0.131	0.048

At week 13, PVI increased body weight by 52.43 g in correspondence with the control. As well, the pullets have a body weight like the genetic line for week 13. At week 14, body weight and feed intake were the majority for the group with PVI at 32 g and 20.93 g, respectively. The pullets had 97.80 % of the ideal line weight for week 14. It is known that PVI has a peptide profile of less than 500 Dalton (^{Martínez 2021}). According to ^{Hou et al. (2017)} a smaller size of peptides causes positive results in growth and intestinal health due to better absorption compared to other free amino acids. Furthermore, ^{Xue et al. (2021)} indicated that smaller peptides increase the number and size of villi in the small intestine compared to other complete proteins.

This is consistent with this study where PVI peptide molecules are small, confirming that PVI peptides may be involved in intestinal health and nutrient absorption. At week 15, 39.58 g and 16.68 g were the difference found for body weight and feed intake, respectively, in the group of pullets that consumed PVI. The pullets had 99.83 % of the ideal weight of the line for week 15. The feed conversion ratio varied depending on the stimulation of intake and the weight gain in each productive week. The PVI provoked the highest feed conversion ratio in week 14, this was due to the fact that the weight gain in relation to the control was lower than in the previous week (32.38 vs 52.43 g) and the feed consumption maintained the same trend.

In the pre-lay phase, the use of PVI improved (P<0.05) the body weight of the pullets at weeks 16 and 17. Also, at week 16, the group with PVI decreased feed conversion ratio (P<0.05) and the other indicators did not change due to the effect of the diets (P>0.05). In the period of 1-17 weeks, PVI promoted feed intake (P<0.05), although without changes (P>0.05) in feed conversion and viability (table 6).

Table 6 Effect of dietary inclusion with a processed vegetable ingredient on growth performance of pullets in the pre-lay phase (13-15 weeks) 

Items	Experimental treatments		SEM±	P-value
	Control	Processed vegetable ingredient
Week 16
Body weight (g)	1125.05	1165.16	5.427	0.021
Feed intake (g)	532.53	513.75	16.245	0.422
Viability (%)	99.83	99.83
Feed conversion ratio	33.67	31.16	5.965	0.002
Week 17
Body weight (g)	1162.65	1214.44	7.132	<0.001
Feed intake (g)	485.78	497.10	19.428	0.684
Viability (%)	100.00	100.00
Feed conversion ratio	12.92	10.09	0.276	0.089
Week 1-17
Feed intake (g)	6879.10	7639.75	21.528	0.050
Viability (%)	99.30	99.14	0.084	0.860
Feed conversion ratio	6.10	6.48	0.136	0.058
Uniformity (%)^*	89.90	90.42	0.357	0.089

^*According to method±10

At week 16, it is observed that the PVI improved the body weight of the pullets by 40 g. The pullets are 97.90 % of the ideal line weight for week 16. At week 17, it is observed that the PVI improved the body weight of the pullets by 51.79 g. The pullets had 98.70 % of the ideal weight of the line for this week and the feed conversion ratio does not statistically increase. Consequently, it is known that pullets can be subjected to different stressors, especially when the holding conditions are not optimal, which directly affects the productive response and viability. ^{Kamel et al. (2021)} assure that stressful conditions can improve the effect of nucleotides on intestinal morphology.

In this sense, ^{Leung et al. (2019)} informed better results with the use of nucleotides in pullets subjected to Eimeria spp. It should be noted that even though the production conditions were optimal, this new feed product provoked a functional effect due to growth promotion. Globally (1-17 weeks), it is observed that despite the fact that the use of PVI caused a stimulation of the consumption of the birds, the feed efficiency was similar in both groups, because the live weight increased by 4.08 % compared to the control. Although there are few studies that evaluate feeds rich in peptides in pullets, other studies in fast-growing birds indicate similar results (^{Feng et al. 2007}, ^{Karimzadeh et al. 2016} and ^{Osho et al. 2019}). Thus, PVI could be considered as an alternative to subtherapeutic antibiotics, although further studies are needed to confirm this hypothesis.

On the other hand, ^{Zuidhof et al. (2017)} mentioned that a heterogeneous flock can cause delayed start of lay, low egg production and variability in egg weight. In this sense, the use of PVI did not depress the uniform development of the poultry mass, which may favor the synchronization of the arrival at sexual maturity with egg production. It is important to noted that ^{Gous (2018)} refers that a good uniformity is greater than 80 %, according to table 2, the results showed higher percentages according to the ±10 method (89.90 vs 90.42 %).

Conclusions

The dietary inclusion with a processed vegetable ingredient (MrFeed^® Pro50 C) naturally promoted the growth of the pullets from the third week old, without changes in viability, uniformity, feed intake and feed conversion ratio in the period from 0 to 17 weeks.

References

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Received: September 02, 2022; Accepted: January 05, 2023

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Conflict of interests: The authors declare that there is no conflict of interest between them.

Authors contribution: K.D. Coello: Data curation, Investigation, Formal analysis, Writing - original draft. L.A. Castellanos: Data curation, Investigation, Formal analysis, Writing - original draft. P. Paz: Investigation, Formal analysis. M. Valdivié: Formal analysis, Writing - original draft. Y. Martínez: Conceptualization, Data curation, Investigation, Formal analysis, Writing - original draft.