Effect of sugarcane silage on productive parameters of replacement Holstein-Friesian heifers

Objective. Measure the productive parameters of Holstein-Friesian females from weaning to 470 days old, comparing feeding through sugarcane silage (SCS) and corn silage (CS) in a concentrated fodder ratio of 70:30. Materials and methods. Twenty-eight post-weaning calves were used, with an average age of 80±16 days old and an initial weight of 79.5±12.9 kg. The T-Student test was used for the comparison of means, where calves were divided into two groups of 14, one for each treatment. The body weight BW (kg), wither height WH (cm), body condition BC (1 to 5 scale), daily weight gain DWG (kg) and feed conversion FC (kg) was measured every 30 days. Results. Differences were found between treatments, where heifers fed with SCS showed better BC (3.12), FC (7.4) as compared to the CS treatment. No significant differences were found in terms of DWG (0.666 and 0.743 kg/d). Conclusions. Feeding based on sugarcane silage allows for an improved body condition and feed conversion of animals having with this an acceptable and cost-effective production performance in the raising of dairy replacements.


INTRODUCTION
Breeding is a vital component of modern dairy farms, as it provides a consistent and costeffective supply of high-quality replacements, this goal is achieved through the implementation of efficient breeding systems both in nutrition as in health to ensure this purpose, adapting the same to the particular region and exploitation (1).In this sense, Schingoethe and Garcia (2) point out that one of the main factors limiting the development of dairy farming is the raising of replacement heifers, so it is essential to seek alternative solutions and design production systems according to the socio-economic reality, which in the case of the milk industry result in efficient, attractive and economically affordable production for the producer, as well as being accessible for the entire population and allow the cost-effective breeding of replacements for the preservation of these systems.
In bovine production fodder plays a critical role, since it is the most economical source of nutrients, among these silages are renowned by their low variation in nutritional quality (3,4).Therefore, the silage of fodder crops could be an option that contributes significantly to optimize the operation of animal production systems (dairy replacements) in tropical and subtropical areas.Although appropriate supplements are required to improve production, preferably slow consumption with appropriate inputs of nitrogen, lipids and minerals to correct constraints (5,6).
Sugarcane is possibly the herbaceous crop with the highest performance in terms of biomass per area and time unit.It outperforms other highyield plants such as corn and wheat.Its ability to maintain high digestibility with growing maturity provides an important advantage as food for ruminants, especially during the dry season when most other fodders are unavailable and of low quality (6,7).
The lack of information concerning the development of Holstein-Friesian heifers that will be the future replacement of animals in production and their development with local
La falta de información referente al desarrollo de vaquillas Holstein-Friesian futuros reemplazo de animales en producción y su desarrollo con recursos forrajeros y alimentos locales, inducen a desarrollar éste tipo de trabajos por lo que el objetivo de este estudio fue evaluar el sistema de alimentación basados en ensilado de caña de azúcar en el desarrollo de becerras Holstein-Friesian.
Las becerras fueron manejadas en dos lotes distribuidas al azar; en donde se propuso una relación de forraje:suplemento (70:30), base seca y se ofertó un consumo a razón del 3% de su peso corporal en materia seca.El tratamiento testigo fue el sistema de alimentación tradicional del Rancho con base en ensilado de maíz (Zea mays), rastrojo de maíz, heno de pasto Rhodes (Chloris gayana), concentrado comercial al 16.5% de proteína mediante una ración integral y el experimental con ensilado de caña de azúcar (Saccharum officinarumm) y un suplemento activador del rumen (SAR; Tabla 1) de forma separada del forraje.A los alimentos utilizados se les analizó su composición fodder and food leads to the development of this type of work, hence the objective of this study was to evaluate the feeding system based on sugarcane silage in the development of Holstein-Friesian heifers.

MATERIALS AND METHODS
Study site.This study was carried out in the Agricultural Farm "DOS PIVOTES" engaged in the production of milk and breeding stock (replacement heifers and stallions), and the production of sugarcane for the industry.The ranch is located to the southwest of the Municipality of Zapotlan El Grande, in the State of Jalisco, Mexico; with geographic coordinates 19°27'13" north latitude and meridians 103°27'57" west longitude, with an altitude of 1.520 m.The climate is warm, with average annual rainfall of 732 mm distributed in the months of June to September, and occasional winter or summer rainfall.Its average temperature is 20.2°C (8).
Procedures.Twenty-eight Holstein-Friesian calves were used with an initial average age of 80±16 days old and an average live weight of 79.5±12.9kg.The body weight was measured every 30 days, the weighing of the heifers was carried out through the measurement of the thoracic perimeter with a tape in centimeters and the use of a live weight conversion table, the wither height was measured with a metallic vertical ruler of 1.5 m and a sliding set-square of the same material, body condition (BC) with a 1 to 5 scale according to Edmonson et al (9), daily weight gain DWG (kg), consumption (g MS/kg PV 0.75 ) and feed conversion (FC), during a period of 470 days.Animals were treated with ivermectin.At three months of age the bacterin Brucel R RB51-PLUS for brucella was applied and the vaccination was strengthened one month later.Between four and five months old, a vaccine for bovine respiratory disease complex was administered (Express TM 10 HS), Pasterella (One-Shot TM ) and Clostridium (Barvac TM ) (10).
Heifers were handled in two lots distributed randomly; where a fodder:supplement ratio of (70:30) was proposed, dry base and a consumption rate of 3% of their body weight in dry base was suggested.The control treatment was the traditional feeding system of the Ranch based on corn silage (Zea mays), corn stover, Rhodes grass hay (Chloris gayana), commercial concentrate with 16.5% protein through a full portion and the experimental system with sugarcane silage (Saccharum officinarumm) and a supplement for the activation of rumen (SAR; Table 1) separately from the fodder.The foods used were analyzed for their chemical química de acuerdo a la AOAC (Tabla 2) (10).Para el cálculo de la energía metabolizable se utilizó la fórmula: 1.81+0.064×%ProteínaBruta=Mcal EM kg -1 MS (11).
Statistical analysis.The obtained data were analyzed using the T Student test (12).

RESULTS
The results obtained are shown in table 3. Higher consumption was observed with the corn silage strategy; however, the ratio in the consumption of fodder-concentrate for the system based on sugarcane silage remained homogenous until the end of the experiment.
Young animals had a lower consumption of fodder, which increased as the animal grew.The feed conversion was better for the sugarcane silage strategy; the evolution of consumption expressed in dry base was observed as a similar initial consumption for the two systems, but after 200 days of age better consumption was recorded in total dry base for the corn silage system, although this was not reflected in a significantly higher DWG, thus the SCS having better feed conversion; thereby demonstrating that its use may be more advantageous than CS.Reproductive results show a variation in terms of productive behavior in relation to the productive strategy employed according to the development stage of cattle.
In the first stage that ends at 350 days of age, both the weight (p<0.035) and body condition (p<0.001) had significant differences in these variables, the corn silage system resulted in higher values.For the second stage ending at 470 days of age, a favorable difference in the body condition (p<0.01) was observed al sistema basado con ensilado de maíz, y en las demás variables no existió diferencia significativa.
in comparison to the corn silage system, and the other variables showed no significant difference.
The results of consumption of g MS/kg of metabolic weight, feed conversion and consumption rate in the two stages, are shown in table 3, with no difference (p<0.05) in the first stage for the three variables.In the second stage there was a difference in the three variables under study (p<0.01),with higher values for consumption both in MS/kg PV 0.75 and consumption rate; however, the best feed conversion was obtained with the sugarcane silage system.
With regard to the economic variables, feeding cost/d and feeding cost/kg, these were different (p<0.001),noting that the sugarcane silage system showed the lowest feeding costs in the two stages evaluated, having as result that the use of SCS may have the same parameters as the use of CS, but it is more profitable economically.

DISCUSSION
The use of sugarcane silage plus a strategic supplement makes it possible to obtain an economically competitive scheme in the development of heifers as future replacements in dairy farming, when compared to the traditional feeding with corn silage.Even considering that at the end of the observation period (470 days), the corn silage system was superior in WH and BC, these results can be attributed to the quality of the base ration, since the energy value calculated for sugarcane silage was lower when compared with corn silage and with a higher content of the acid detergent fiber fraction, which would make the fiber consumed less available, in addition to increased consumption, as it was higher by 1.6 kg MS/d.On the other hand, given the durability and performance of the biomass of sugarcane crops it is possible to increase the number of heifers to be developed with sugarcane silage.
In the productive aspect, both silage strategies are within the recommendations of different authors of not exceeding weight gains from 0.700 to 0.800 kg/d in the prepubertal stage (1,13).This rules out the negative effect on prepubertal animals with high nutritional levels of the development of the mammary gland (greasing) and consequently on the milk production (14,15).However, the improvement in the body condition with corn silage could be possibly attributed to a higher greasing, which resulted 27% higher than the sugarcane silage system and the corn silage treatment was superior to the recommendations of a BC of 2.4 at seven months of age, of 2.8 at 11 months and 3.0 at 16 months, compared to 2.9, 3.3 and 3.6 for the CS system, and 2.6, 2.6 and 3.1 for SCS respectively.In this context, it can be explained that the energy supplied in excess of the requirements mainly impacted the body condition (16,17).
Osnaya (18), reports that when working on the development of replacements for Holstein cattle with three feeding strategies: grazing, grazing plus supplementation and intensive system, DWG were 0.508, 0.694 and 0.560 kg, respectively.In this sense, when comparing the results of the sugarcane silage system with tropical pastures, these resulted in higher returns than those indicated by In this context, the possibility of implementing sugarcane silage feeding in growing animals is attractive, since it would have a greater impact on the drought period.Likewise, the consumption of MS was similar to that reported for Holstein heifers with different body weights (22).Therefore, one possibility of increasing consumption with this type of strategy is through the improvement of the fodder characteristics of sugarcane or the increase of the contribution of the supplement.
The SCS system proved to be more economical in 13%, as compared with the CS system, which means savings in feeding and therefore in the production of replacement heifers, reducing costs in 16.8% in the first stage (prior to weaning) and up to 18% in the second phase of this study, this is the result of the use of fodder crops adapted to local conditions and with high productivity as it is the case of sugarcane silage.
In conclusion the corn silage system produces a higher body condition, related to greasing, thereby affecting reproductive efficiency.An alternative for the development of Holstein-Friesian heifers was generated using a system based on sugarcane silage and slowconsumption supplement for replacement females from weaning until gestation for the dairy industry.

Table 1 .
Percentage composition of the supplement for the activation of rumen.

Table 2 .
Chemical composition of the ingredients used in diets for the development of replacement Holstein-Friesian heifers.Sugarcane silage; b Corn silage; c Supplement for the activation of rumen; d Commercial concentrate; e Corn stover; f Metabolizing energy Mcal/kg a

Table 3 .
Average productive performance of different variables in Holstein-Friesian heifers in two feeding systems until puberty.
a Sugarcane silage; b Corn silage; c Standard error of means; d Probability.* Expressed in US dollars.