Effect of different sources of lipids in diet on the qualitative characteristics of Longissimus thoracis muscle of cattle finished in feedlots

1 Programa de Mestrado em Saúde Ambiental, FMU, São Paulo, SP, Brazil. 2 Agricultural Sciences Center at UFSCar, Araras/SP, Brazil 3 UNESP/FCA, Botucatu/SP, Brazil. 4 Faculdade de Ensino Superior e Formação Integral – FAEF, Garça/SP, Brazil. 5 Instituto Federal Goiano, Posse Campus /GO, Brazil. 6 Instituto Federal do Mato Grosso, Campo Novo do Parecis Campus/MT, Brazil. 7 University of Southern Bahia, Teixeira de Freitas/ BA, Brazil.


INTRODUCTION
The livestock beef cattle production is important activities of the agribusiness in Brazil, being one of the largest exporters of beef in the world.The farms seek to produce efficiently and with this new demand for quality meat.The *Corresponding author.E-mail: ericozoo1@yahoo.com.br,Tel: +55 19 982153505.Author(s) agree that this article remain permanently open access under the terms of the Creative Commons Attribution License 4.0 International License consumers search products competitiveness and require the availability of low cost and better quality (Ruviaro et al., 2014).
To Brazil, maintaining this condition each year has expanded the studies on nutrition of ruminants on the performance and carcass characteristics and meat.One of the main problems encountered in the feeding of cattle confined is related to metabolic disorders caused by the excess of high carbohydrates such as starch fermentation in rumen.The increase in the supply of lipid can be an alternative to reduce the inclusion of starch, maintaining the same energy level of the diet.Thus, the cottonseed has long been used in the feeding of ruminants with this purpose.
However, excess dietary lipid can cause negative effect on fiber digestion in the rumen and influence on quality of meat (Rogério et al., 2003).One way to avoid this negative effect of lipid on the microorganism that digests fiber in the rumen is the supply of protected lipid in the rumen biohydrogenation (Aferri et al., 2005).However, in the literature there are few results the use of protected lipid on the characteristics of quality of meat.
The objective of evaluation the influence of whole cottonseed and of protected lipid on pH, color of meat and fat, the tenderness and cooking the Longissimus thoracis muscle of cattle finished in feedlots.

Study location
The study was carried out in the Chapéu de Couro Farm, located in the city of Aguaí/SP, Brazil, at 22°04′00″ South, 47°09′03″ West, average altitude of 615 m above sea level.The region is characterized by a hot and humid seasons from October to March, followed by a cold and dry season from May to September.The climate of the region is Cwa in the Köppen classification (mesothermal, with hot and humid summers and dry winters).

Animal management and treatment
A group of 39 uncastrated, Nellore animals raised in Brachiaria humidicola pastures was used in the study.Mean age of the animals was 36 months and initial mean live weight was 494.1 ± 10.1.Animals were identified and dewormed with Ivermectin 1% before the beginning of the trial.Then, animals were randomly assigned to one of three treatments, based on dry matter: feed with 2.50% CS (control diet), feed with 11.50% CS, and feed with 3.13%% CS added of 1.77% protected lipid (PL).Animals were confined for 63 days (experimental period) in collective pens of 247 m 2 (19 m 2 per animal).The confinement facility was made up of three pens with sand floors, with 13 animals per pen.Feeders and drinkers in these pens were provided with roofs and animals had free access to them.Feeders were made of concrete, and the length available per animal was 0.70 m.A 10-day period was used for the adaptation to the diet and management prior experimental period, in which concentrate was gradually added to the feed, until a 50:50 forage:concentrate ratio was reached.The experimental diets were formulated in the CNCPS software 4.0 (CNCPS, 2000) for uncastrated finishing cattle to provide weight gains of 1.4 kg/animal/day.Forage:concentrate ratio was 50:50 on a dry matter basis.All the concentrate ingredients and forage were weighted in order to prepare the experimental diets, using electronic weighing scale kg.Sugar cane chopped was used as forage, and concentrate was made up of urea, cracked corn kernels, citrus pulp, cotton meal, CS and/or PL.The PL used in this study was made from soybean vegetable oil and had fatty acid calcium salts in its composition.Animals were fed twice a day at 8 am and 4 pm, in a total mix diet, with about 5% leftovers that were weighted in the morning for diet adjustment.Nutritional composition of the diets is shown in Table 1.

Procedures for data collection
After thawing, composite samples of a 21-day period were obtained.Samples of feed and forage were weighted and pre-dried at 60°C for 72 h.Then, they were weighted again in a mill with 1mm sieves, and stored in plastic bags.Samples of the experimental diets were sugar cane and concentrate which were collected every seven days, placed in plastic bags and stored in at -4°C for subsequent measurements.
The samples were analyzed for Proximate Analysis according to AOAC (1990) and NDFom and ADFom (excluding ash) according to procedures of Van Soest et al., 1991), and lignin by the sulphuric acid method Lignin (sa), after a sequential neutral-acid detergent extraction (Van Soest et al., 1991).In the NDF analyses, thermostable α-amylase was used without sodium sulfite (Mertens, 2002).Non-fiber carbohydrates (NFC) in the ingredients of the diets were determined by the following equation, according to Sniffen et al. (1992), NFC = 100 -(%NDFcp + %CP + %EE + %MM).Due to the presence of urea in the diets, NFC in them were calculated as indicated by Hall (2000) 2 and 3.

Slaughter procedures and sample preparations
After 63 days of the study, animals were weighted for the last time after a 14-h solid food fasting.Mean final live weight was 577.01 kg ± 11.34.Soon after being weighted, animals were taken to a slaughterhouse (FRIGONOBRE, in the city of Torrinha, state of São Paulo), 166 km from the study site, in solid food fasting until the moment they were slaughtered.Animals were slaughtered according to the regular flow of the industry.
After slaughter, carcasses were identified and divided into two halves that were kept in a cold chamber for 24 h at 2°C.Using pH meter was determined post-mortem pH in Longissimus thoracis muscle between the 12 th and 13 th rib of the left half carcass.After, part of each animal was removed, and divided in three samples (steaks).Steaks were 2.5 cm thick and were identified and stored individually in plastic bags under vacuum.Samples were frozen in a freezer at -18°C at Universidade Estadual Paulista, Faculdade de Ciências Agronômicas, Botucatu campus, at the Animal Products Technology Laboratory.

Chemical analysis of the meat and fat color
Samples of Longissimus thoracis muscle of each animal were thawed in refrigerator, then removed from the packaging and exposed to the air for 30 min to allow oxygenation surface.The color of the meat was determined by the Minolta colorimeter CR-410 and the color of the subcutaneous fat, using the optional Milnolta CR-400 second Honikel (1998).The parameters evaluated were L*, a* and b* the CIELab system, where L* is brightness, a* represents intensity of red and b* intensity of yellow.

Cooking yield and shear force (aged beef)
The samples were weighed in the balance semi-analytical and submitted to cooking on a grid until they reach the automatic internal temperature of 71°C, as measured by a digital thermometer in the geometric centre of the sample.The evaluation of proceeds in cooking was made by the difference between the weights of the samples before and after cooking according to the methodology of Honikel (1998).The same samples cooked were refrigerated by 12 h the 4°C, and then cut into cylinders 1.10 Øcm with the support of a drill press avoiding fats and nerves.Shear force was calculated in these samples cut into cylinders through the Brookfield texture CT3 Texture Analyzer 25 k equipped with a set of blade Warner-Bratzler according to the methodology of Savell et al. (2015).

Statistical procedures and model evaluation
A completely random design with 3 treatments and 13 repetitions was used, according to the Υij = μ + Ti + eij model, where: Yij is the value observed in the j th experimental unit (animal) that received the i th treatment; μ is the overall mean; Ti is the fixed effect of the i th treatment ; eij is the experimental error related to the experimental unit.Data were analyzed by means of the Generalized Linear Models Procedures (GLM).The averages were adjusted by the method of least squares (Least Squares Means).Statistical analyses were performed using the SAS program ( 2002), and means were compared using Tukey test at a 5% significance level.

RESULTS
The characteristics the meat and subcutaneous fat the Nellore cattle was shown in Table 4.No differences in pH 24 h after slaughter were observed in the meat of Nellore cattle fed different sources of fat (Table 4), and mean value for this variable was 5.59.Difference was not observed (P > 0.05) to cooking yield of muscle Longissimus thoracis the Nellore cattle fed lipid sources.However, for the shear force differences (P < 0.05) were founded.For diet control the lowest value found 5.10 (kg) while for the treatment with 11.50% CS the great value found was 6.30 (kg).It may be observed in Table 4, for Brightness L*, intensity the red a*, intensity of yellow b* that there were no differences (P>0.05) between the treatments for characteristics the meat or fat.

DISCUSSION
After 24 h analysis of pH post-mortem of the Nellore cattle the mean value for this variable was 5.59.In the same way as, findings similar to those of the present study were reported by Aferri et al. (2005), who studied the use of additional fat in the diets of confined crossbred beef steers.These authors did not find any differences between the diets containing or not the lipid source, either.They reported a mean pH value of 5.56 after 24 h of slaughter.
As uncastrated animals are more easily stressed, according to Luchiari Filho (2000), inadequate management during management, transportation, and slaughter may lead to dark, firm and dry carcasses.This condition is always observed when pH is greater than 6.0.In Brazil, slaughterhouse export only meat with pH is lowers than 5.8, determined directly on the Longissimus thoracis muscle 24 hours after slaughter (Fernandes et al., 2008).Mean pH 24 h after slaughter in the present study (Table 4) suggests that stress was not too high before slaughter, as muscle acidification was inside the expected range.
For shear force different the results observed in this study, Costa et al. (2013) found no differences in shear force on Longissimus thoracis thoracis muscle of cattle fed growing Nellore whole cottonseed levels in the diet, as well as Aferri et al. (2005) and Andrade et al. (2014) also did not observe differences by including whole cottonseed or rumen protected lipid in diet.Second, Labrune et al. (2008) as worked with a lipid-rich diet and not observed change in shear force on tenderness or succulence of meat from steers.High shear force values mean greater texture of meat that indicates less tenderness.The texture of the meat can be influenced by age, weight to the slaughter of animals.For cattle breed Nellore Bos taurus indicus more high value of shear force (Shackelford et al., 1994).
For cooking yield of cattle fed lipid sources showed no differences.Similar results were founded for Aferri et al. (2005), Costa et al. (2013) and Andrade et al. (2014) did not observe differences to the loss by cooking to feed cattle with whole cottonseed or protected lipid.When cooking meat compounds losses include free amino acids, peptides, reducing sugars, vitamins and lipids (Watanabe et al., 2015).
In studies with brightness the meat second Suman et al. (2014) to improve beef color and attempted to logically explain the fundamental mechanisms involved.However, the surface color and its stability are critical traits leading the marketability of fresh beef when sold, while internal cooked color is utilized as an indicator for doneness at the point of consumption.For brightness L*, intensity the red a*, intensity of yellow b* the muscle initial red color intensity increased whereas both mitochondrial oxygen consumption and color stability decreased.The decrease in mitochondrial oxygen consumption associated with longer aging times will increase initial color intensity (Mancini and Ramanathan, 2014).Similar result founded in study case Costa et al. (2013) no differences in this characteristics is this feature evaluated for cattle fed with increasing levels of whole cottonseed in the diet.Same results were observed for Oliveira et al. (2012) with meat color composition evaluated from Nellore cattle fed fat protected lipids and did not view an alteration in these parameters, due to the consistency in the breed, age and meat pH of the animals.

Conclusion
The supply of protected lipid in the diet of cattle does not influence the quality of the meat.The whole cottonseed does not contribute to the improvement of texture and tenderness of the meat.
: NFC = 100 -[(%CP -%CP from urea + %urea) + %NDFcp + %EE + %Ash].Estimated metabolizable energy (ME) in Mcal/kg of DM was determined according to the NRC (1996) recommendations, considering that 1 kg of total digestible nutrients (TDN) contains 4.409 Mcal of digestible energy (DE), using 0.82 as the conversion factor to transform DE in ME.Analyses of the feed samples were carried out in the Food Analysis Laboratory at the Animal Nutrition and Improvement Department of Faculdade de Medicina Veterinária e Zootecnia at Universidade Estadual Paulista, Botucatu campus.Results of these analyses are shown in Tables

Table 1 .
Chemical composition of the experimental diets on a dry matter basis.

Table 2 .
Mean chemical composition of ingredients used in the experimental diets as percentage dry matter.

Table 3 .
Mean chemical composition of experimental diets used in different levels of cotton seed.

Table 4 .
Characteristics aging times of meat and subcutaneous fat color the Nellore cattle fed with different diets.
1 According to Tukey test (P< 0.05); a, b Different letters in line indicate significant difference.CS = cottonseed; PL= protected lipid; SE = standard error.