This study examined the effects of cottonseed processing form and
the inclusion of calcium lignosulfonate in high-concentrate diets for
feedlot cull ewes on carcass traits and non-carcass components. Thirty Santa
Inês cull ewes with an average body weight of 44.2
A large portion of the sheep meat consumed in Brazil originates from adult animals, which are mostly culled. However, labels on these products on the market do not provide information on sex, category, age (young or adult), or whether the animal was culled (Pinheiro et al., 2007, 2009). The use of cull animals has been a commonly adopted practice on farms that undertake the entire production cycle, as the sale of these animals is compromised by the low acceptability of their meat (Pelegrini et al., 2008). Furthermore, they do not have the productive and reproductive potential expected of them (Atti et al., 2001).
To increase the profitability of the activity, producers must plan a proper destination for these animals. This is particularly important for females, whose productive and reproductive potential is no longer satisfactory at an earlier age. In this respect, production can be maximized with the adoption of feedlotting, a technique that allows rapid weight gains and, as a consequence, better carcasses.
In recent years, greater value has been placed on edible organs such as offal, skin, and waste used by industries. This, coupled with the association made between these components and carcass yield (that in feedlot sheep heavier weights translate into lower carcass yields), has driven research into non-carcass components (Kuss et al., 2007; Bhatt et al., 2012, 2013; Ben Abdelmalek et al., 2019).
Feed is known to be the costliest factor in an animal production system. In an attempt to lower these costs, by-products emerged as an alternative to replace the most commonly used diet ingredients (corn and soybean meal) without affecting animal productivity or meat quality (da Silva Magalhães et al., 2020; Nascimento et al., 2021; Silva et al., 2021). In this context, oilseeds are lipid sources used to increase the energy density of the diet and improve animal performance (Manso et al., 2006; Homem Júnior et al., 2010) as well as the quality of the carcass and meat (Jerónimo et al., 2009; Atti et al., 2013).
Among the available high-fat options, cottonseed (
Calcium lignosulfonate, a by-product of the cellulose industry (Khitrin et al., 2012), is a highly hygroscopic energetic binder that surrounds fatty acids and inhibits bacterial activity. In doing so, it prevents the deleterious effects of fat and protects grain nutrients from rumen degradation, thereby reducing the availability of lipids in the rumen (Neves et al., 2009) and maximizing intestinal absorption.
In view of the above-described facts, the present study was developed to investigate the effects of cottonseed in different processing forms and the inclusion of calcium lignosulfonate in high-concentrate diets for feedlot cull ewes on carcass traits and non-carcass components.
The experiment was conducted on Malhada das Cabaças Farm (14
Thirty Santa Inês cull ewes with an average initial live weight of
44.2
Five high-concentrate experimental diets were prepared. The diets were
formulated with 100 % concentrate, without roughage. The feed was supplied
twice daily (half at 07:00 and the other half at 15:00) and adjusted daily
to allow orts around 15 % of the total supplied, characterizing
Proportion of ingredients and physical and chemical composition of experimental diets.
The experiment lasted 54 d, of which the first 12 were used for the
animals to adapt to the collective stalls and dietary management. In the
diets, the concentrate was added replacing hay of
Prior to slaughter, the ewes were weighed to determine slaughter weight (SW) and calculate the average daily weight gain (ADG).
Then, in vivo measurements of subcutaneous fat thickness (SFT) and loin-eye area
(LEA) were performed using an ultrasound device
(ALOKA® SSD 500 v) with a 3.5 MHz linear
transducer, a 12 cm acoustic probe, and a silicone coupler. After images were
captured, the ewes were shorn and clipped in the region between the 12th and
13th thoracic vertebrae, on the left side. The best image of the loin-eye
area was captured by measuring it from the medial side of the
Next, the following in vivo biometric measurements were taken with the animals standing on a flat surface: rump height, withers height, body length, chest width, chest girth, rump width, shank circumference, leg length, and shank length. Length and circumferences measurements were taken using a tape measure, whereas the width and depth variables were measured with a measuring stick. Body compactness was determined as the ratio between slaughter weight and body length.
At the time of slaughter, the animals were transferred to the slaughterhouse located in Guanambi – BA, Brazil, where they were slaughtered under veterinary inspection following the current norms established by the Regulation for Industrial and Sanitary Inspection of Products (Brazil, 2000).
After bleeding and skinning, the carcasses were eviscerated and the
non-carcass components were separated into rumen–reticulum, omasum–abomasum,
small and large intestines, heart, liver, kidneys, lungs–trachea–esophagus,
tongue, blood, and external body components (head, feet, and skin). The
gastrointestinal tract (GIT) was initially weighed full. Then it was
emptied, washed and weighed again to determine the GIT content and calculate
empty body weight (EBW
Subsequently, the hot carcass weight (HCW) was determined and the hot
carcass yield (HCY) was calculated by the following equation: HCY
After 24 h of refrigeration in a cold room at 4
Following the subjective assessment of pelvic–renal fat, the kidneys and
pelvic–renal fat were removed and their weights were recorded and
subtracted from the hot and cold carcass weights. Next, the cold carcass yield
(CCY) and chilling loss (CL) were calculated using the following formulas:
CCY
Whole carcass length, internal carcass length, shank circumference, shank length, chest depth, chest width, chest girth, chest circumference, rump circumference, and rump width were measured. Carcass capacity was determined as the ratio between cold carcass weight and internal carcass length.
After the morphological evaluation, the carcasses were sectioned lengthwise,
along the spine with an electric saw, which resulted in the separation of
the right and left half-carcass. The left half-carcass was used for direct
(on-carcass) measurements of LEA and SFT. Loin-eye area was determined by
making a cross section between the 12th and 13th thoracic vertebrae and
tracing the outline of the muscle on acetate sheet, in correspondence with
the cranial portion of the loin. The maximum distance and depth of the
muscle were measured with a ruler and calculated from the formula proposed
by Silva Sobrinho et al. (2003), as previously mentioned in the ultrasound
evaluation of LEA. The subcutaneous fat thickness in the carcass was
measured (in mm) using a digital caliper at a
The effects of dietary treatments on the measured parameters were analyzed
according to the following model:
Additionally, the following contrasts were used to compare the effects of
the different diets:
Contrast 1: cottonseed effect {CON vs. (WCS Contrast 2: lignosulfonate effect {(WCS Contrast 3: cottonseed physical form effect {(WCS
All statistical procedures were performed using the PROC GLM procedure of the SAS software (SAS, 2014), adopting 0.05 as the critical probability of type-I error.
Neither the cottonseed processing method nor the inclusion of calcium
lignosulfonate compromised the ADG or SW of the feedlot ewes. The control diet
in comparison to the others (CON vs. other diets), cottonseed processing
method (WCS
Weight gain, biometric measurements, subcutaneous fat thickness
(SFT), and loin-eye area (LEA) of the
There were no differences (
In comparison with the control diet without cottonseed, the inclusion of
calcium lignosulfonate (WCS
The morphometric measurements evaluated on the carcass did not differ (
In the analysis of non-carcass components, neither calcium lignosulfonate
inclusion nor the cottonseed processing method influenced (
The ADG and SW of the feedlot ewes evaluated in this study were considerably higher than the 0.034 and 45.21 kg, respectively, reported by Souza et al. (2010) in Barriga Preta feedlot ewes fed high-concentrate diets, demonstrating the higher potential of Santa Inês ewes for performance and meat production.
Rump and withers heights were similar (
The morphometric measurements of the cull ewes did not differ between the
treatments (
Performance and qualitative traits of the carcass of Santa Inês cull ewes fed high-concentrate diets with cottonseed associated with calcium lignosulfonate.
Morphometric measurements and quantitative traits of the carcass of Santa Inês cull ewes fed high-concentrate diets with cottonseed associated with calcium lignosulfonate.
The average body compactness indices found in the ewes of the present study
were higher than the 0.61 described by Pinheiro and Jorge (2010). This may
have been due to the better nutritional composition of the diet supplied in
this study (17.38 vs. 11.81 % CP), which resulted in higher weight gain
(SW
Non-carcass components (% of the empty body weight) of Santa Inês cull ewes fed high-concentrate diets with cottonseed associated with calcium lignosulfonate.
The LEA and SFT results obtained by ultrasound may be attributed to the fact that the animals were slaughtered at similar body weights. This finding corroborates the following inference drawn by Osório (2002): when carcasses have similar weights and amounts of fat, almost all body regions have similar proportions, irrespective of the breed. Loin-eye area and SFT are traits used as indicators of muscularity and fatness, respectively (Souza Júnior et al., 2013; Al-Jammas et al., 2016).
In the current study, HCY and CCY were higher than the 45.0 % and 44.7 % reported by Pinheiro et al. (2009) and 45.2 % and 43.7 % described by Pelegrini et al. (2008) in Santa Inês and ideal feedlot cull ewes, respectively. These results confirm the presuppositions that when fed diets of better nutritional quality and specialized in and having potential for meat production, feedlot ewes exhibit higher performance and, consequently, higher carcass yields.
The morphometric traits of a carcass vary according to breed, sex, and diet (Murta et al., 2009). Therefore, the similarity found between the treatment groups in this study can be explained by the similar composition of the diets, since the animals shared the same sex, breed, age, and live weight. In addition, growth in adult animals is limited, which results in similar body measurements (Garcia et al., 2003).
According to Pinheiro et al. (2009), in sheep, changes in skin and udder weight are directly related to the animal's age and physiological stage. The liver and renal fat, on the other hand, are more affected by compensatory gain. Thus, part of the weight changes is the result of the recovery of the liver's metabolic activity and, consequently, the increased weight of these organs. This may explain the heavier weight of the udder and liver in the animals that received diets with inclusion of calcium lignosulfonate, which exhibited a higher absolute weight at slaughter (Table 4).
Calcium lignosulfonate improves nitrogen metabolism by increasing recycling (Cirne et al., 2020). This effect probably contributes to increasing liver activity and, as a consequence, animal size. Additionally, this enhancement can increase the number of cells in the udder or its activity by increasing its size.
The cottonseed-containing diets, whose neutral detergent fiber (NDF) content was higher due to the ingredient, were expected to result in a larger GIT content and, consequently, a higher volume of its components, given the longer residence time of this feed in the rumen. Alves et al. (2013) and Medeiros et al. (2008) observed this phenomenon in their experiment, where they describe higher GIT contents in Santa Inês and Morada Nova sheep, respectively, which were fed a high-fiber diet. Nonetheless, the increase in GIT content is thought to be greater when diets rich in roughage-derived fiber are used. Moreover, because the animals received diets with a similar physicochemical composition and were subjected to the same pre-slaughter fasting time, this response may be considered biologically normal.
Neither the cottonseed processing method nor the inclusion of calcium lignosulfonate in high-concentrate diets affects the performance, biometric or morphometric measurements, non-carcass components, or qualitative traits of the carcass of cull ewes. In addition, the inclusion of calcium lignosulfonate increases the proportions of liver and udder relative to empty body weight.
Further research is warranted to elucidate the effect of cottonseed processing method and the inclusion of calcium lignosulfonate in high-concentrate diets for sheep.
The original data used in this study are available from the corresponding author upon request.
Conceptualization, design of experiments, data acquisition, data analysis and writing and editing: PTV. Conceptualization, design of experiments, data analysis and writing and editing: GGPdC. Data acquisition: MCPV, DYCdAN. Data analysis and writing and editing: MPdF, LGAC, JSF, LSS, HAdSJ. All authors contributed to refining the text and approved the version to be submitted.
The authors declare that they have no conflict of interest.
Publisher’s note: Copernicus Publications remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
This paper was edited by Manfred Mielenz and reviewed by two anonymous referees.