Influence of cattle category and slaughter age on Charolais-breed carcase and meat traits

Abstract

The beef consumed worldwide comes from different categories of cattle slaughtered at different ages. The aim of this work was to study the effects of the cattle category (young bulls, heifers, cull cows) and slaughter age on carcase and meat traits, using data on 721 Charolais cattle. At 24h post-mortem in slaughterhouse, 14 carcase traits were measured on each carcase. Then, 2 ribs were collected and aged 14 days. Ten measurements were performed on raw meat (longissimus or rhomboideus muscles) and ten others on longissimus cooked meat. Our results showed that young bulls produced carcases with higher conformation scores, lower fat and meat that had less juiciness, and flavour intensity compared to heifers and cull cows. The carcase traits were more sensitive to variation in the slaughter age than in meat traits. Heifers and cull cows slaughtered at an older age produced heavier carcases. Cull cows slaughtered at above 6 years of age produced carcases with darker muscle and yellower fat. Slaughter age had no effect on the sensory descriptors of cooked meat from all three cattle categories. Heifers slaughtered at earlier than 32 months or later than 36 months produced carcases and meat with similar traits, except for the carcase weight. For cull cows over 6 years old, there was no effect of age at slaughter age on carcase and meat traits. Whatever the cattle category, the slaughter age impacted weakly the traits of raw and cooked meat. Meat from heifers was the most appreciated by trained panellists.

HIGHLIGHTS

• Cooked meat from heifers was better appreciated than cooked meat from young bulls or cull cows.

• In young bulls, slaughter age had no effect on any carcase and meat traits other than intermuscular fat assessed at the 6th rib.

• In cull cows, slaughter age affected mostly carcase traits and weakly meat traits.

Keywords:

• Beef quality
• carcase quality
• sensory descriptors
• slaughter age

Introduction

The Charolais breed is the largest suckler-cattle breed in the EU, accounting for 25% of total cow numbers (Herd Book Charolais 2022). It is appreciated for its breedability (e.g. easy calving, few health problems, great fertility) and meat qualities. The Charolais breed is present in around 70 countries worldwide and is used to improve the genetics of local breeds by crossing. France has the particularity of mainly breeding purebred cattle, with the Charolais breed ranking as the leading suckler-cattle breed, at 18% of all cows in 2021 (Institut de l’élevage and Confédération Nationale de l’Elevage, 2021). For the suckler-cattle breed, French cow-calf farms raise suckler calves until they are weaned. Charolais cattle are reared for meat. This breed represented 42% and 33% of heifers and young bulls slaughtered in France, respectively (Herd Book Charolais 2022). The literature counts a number of studies that have investigated the effect of cattle category on carcase and meat traits, but these studies were mainly focussed on young animals (heifers, steers, and young bulls) from Anglo-Saxon, dairy and crossbred breeds (Pogorzelska-Przybylek et al. 2018; Blanco et al. 2020; Lebedová et al. 2022).

Beef consumption is in decline in both the EU and France, prompting efforts from the French beef sector to increase the quality of meat produced via various production standards specifications, typically such as Label Rouge and Protected Designation of Origin (Ellies-Oury et al. 2019). The beef sector has thus had to adapt carcase and meat traits to meet new market demands (e.g. size of primal cuts, meat quality, local production, environmental footprint). To support the meat sector in meeting these quality expectations, the sector needs a precise characterisation of the quality obtained from the different cattle categories. However, in the last decade, to our knowledge, only Węglarz (2010a) compared the effect of the three major cattle categories (young bulls, heifers, and cull cows) on carcase and meat traits, with a focus on Holstein-Friesian breed. This author observed that heifers produced higher-conformation scores and lighter carcases compared to young bulls and cull cows. The meat (longissimus muscle at 48h post-mortem) from heifers had higher L* and lower a* values than meat from young bulls and cull cows. Few studies have compared carcase and meat traits between cull cows and other cattle categories (Pacheco et al. 2011; Lucero-Borja et al. 2014; Gagaoua et al. 2018), only, Pacheco et al. (2011) and Gagaoua et al. (2018) studied this on the Charolais breed. These studies found that cull cows produced heavier carcases than heifers (Pacheco et al. 2011) and young bulls (Gagaoua et al. 2018). However, Lucero-Borja et al. (2014) did not find any differences in carcase weight between cull cows, steers, and heavy heifers. Lucero-Borja et al. (2014) observed a lower meat tenderness for cull cows than heifers and steers. However, Pacheco et al. (2011) found no effect of animal category (heifers vs. cull cows vs. steers) on several sensory descriptors of beef including tenderness.

Moreover, within a given category, the animals may be slaughtered at different ages. Several recent studies have reported a slaughter age effect on carcase and meat traits (do Prado et al. 2015; Clinquart et al. 2022; Kwon et al. 2022), but related studies addressing the Charolais cattle breed are much older (Dumont et al. 1991; Muller et al. 1992). Clinquart et al. (2022) observed that slaughter age is a main factor of variation for carcase weight and fat score and meat colour, juiciness, flavour and tenderness. However, do Prado et al. (2015) found no effect of slaughter age on carcase weight and conformation in young bulls, but they observed an increase in marbling when the young bulls were slaughtered older. Kwon et al. (2022) observed that the oldest steers produced heavier carcases, but that slaughter age had no effect on marbling.

Previous studies have separately shown that cattle category and slaughter age have effects on carcase and meat traits. However, there is little published data for the Charolais breed. Here we set out to test the hypothesis that cattle category and slaughter age could have different effects on carcase and meat traits in the Charolais breed. Using updated data, we studied the effects of three cattle categories (young bulls, heifers, and cull cows) and slaughter age within each category on carcase and meat traits.

Material and methods

The method used in this study did not alter the conditions under which the animals were raised and slaughtered. The animals used in this study were reared on private farms following the production routes set up by the breeders in compliance with French cattle breeding standards in force at the time of the study.

Animals, slaughtering, carcase traits, and meat sampling

Data on 721 Charolais cattle (371 cull cows, 179 young bulls, 171 heifers; Table 1) was collected from 46 French cattle producers, all localised in the French Charolais production area. The animals were slaughtered between April 2019 and December 2020 in five French industrial slaughterhouses (Puigrenier, Monluçon; SICABA, Bourbon-l’Archambault; SICAREV, Roanne; SOCOPA, Villefranche-d’Allier; Viandes de Bresse, Bourg-en-Bresse) in compliance with European regulation No. 1099/2009 on the protection of animals at the time of killing ((EC) European Commission 2009).

Table 1. Description of the slaughter age classes according to cattle category.

Cattle category	Slaughter age classes	n	Mean	SD	Min	Max
Young bulls	≤16 months	53	15.4	0.6	13.9	16.0
	]16 months; 18 months]	87	16.8	0.5	16.1	18.0
	>18 months	39	19.7	1.2	18.1	21.7
Heifers	<32 months	63	28.5	3.0	21.0	31.9
	[32 months; 36 months]	58	33.7	1.1	32.0	35.9
	>36 months	50	40.6	2.9	36.2	46.6
Cull cows	<6 years	156	4.4	0.8	2.5	5.9
	[6 years; 9 years]	122	6.0	0.9	6.0	8.9
	>9 years	93	10.9	1.5	9.0	15.8

n: number of animal; SD: standard deviation.

After slaughter, the carcases were hung vertically using the Achilles suspension method, then weighed and visually graded for the fatness and conformation scores according to the EUROP system ((EC) European Commission 2006). In the EUROP system, the fat score is graded into five ordered classes from 1: lean, to 5: very fat, and conformation score is graded into five classes from E: very high, to P: very poor development. The conformation classes are subdivided into 3 subclasses (low: ‘-’; average: ‘=‘, and high: ‘+’). Therefore, as described in Soulat et al. (2018a), we used a conformation scale from 1 (very poorly muscled, corresponding to P-) to 15 (extremely well-muscled, corresponding to E+).

At 24h post-mortem, the right-hand side of carcases was cut at the 6th rib level, and trained slaughterhouse operators assessed 11 carcase traits on the cut section as described by Soulat et al. (2022): longissimus muscle (LM) seepage, intermuscular fat, subcutaneous fat, nerves, overall meat grain, LM meat grain, rhomboideus (RH) meat grain, fat colour, colour homogeneity of muscles, LM colour, and marbling. Briefly, the same expert went to each slaughterhouse and trained an operator to evaluate these measures on 10 carcases for around 2–3 h. LM seepage, intermuscular fat, and nerves were visually evaluated. The overall meat grain, LM meat grain, and RH meat grain were evaluated both visually and by touch using a scale from 1 (smooth, soft, without harshness) to 5 (very rough/granular) in 0.5 (Ellies-Oury et al. 2013). The meat grain measure, which is generally performed by retailers or butchers, gives butchers an indication of the potential tenderness of the carcase. Fat colour, and LM colour and marbling were assessed using colour charts ((UNECE) United Nations Economic Commission for Europe, 2016).

A meat sample (5th and 4th ribs) localised in the chuck retail cuts section was collected on the right-hand side of each carcase. These boneless meat samples were then individually vacuum-packed and aged for 14 days at 4 °C, then kept in storage at −20 °C until analysis.

Meat measurements

Details of the measurements performed on the meat samples can be found in Soulat et al. (2022). Briefly, professional butchers (INRAE Unité expérimentale Herbipôle, Theix, France) dissected the rib to separate the LM and the serratus ventralis muscle (SV). The meat analyses were performed on the LM as it is the muscle most widely used in studies on meat qualities. Then, as the rib is composed of many muscles, we performed analyses on the SV (a specific rib muscle in the chuck retail section) to observe the effects of cattle category and slaughter age on another non-LM rib muscle to acquire new knowledge (different rib muscles have been under-researched). The LM was used for colour, texture (raw meat) and sensory (cooked meat) analyses. The colour measurement was performed using a spectrophotometer (Konica Minolta CR-400, Osaka, Japan) in the CIE L*a*b* system (Commission International de l’Eclairage 1986). The sensory analyses were performed by a panel trained to evaluate 10 sensory descriptors (intensity of red, initial tenderness, overall tenderness, overall juiciness, presence of nerves, residue, flavour intensity, fat aroma, atypical flavour, and flavour persistence). Each sensory descriptor was rated on a 10-point non-graduated scale from 0 (no perception) to 10 (very intense perception). For this study, 50 persons were trained during 6 one-hour sessions to evaluated the sensory descriptors, according to ISO 8586 8586 (2014). During this period, the panellists were trained to recognise different perceptions and use the sensory descriptor scales. During each sensory analysis session, 10-trained panellists evaluated the 10 sensory descriptors on 8 meat samples (internal temperature of 55 °C) using the Tastel software® (ABT Informatique, Rouvroy-sur-Marne, France). Panel composition sometimes differed between sensory analysis sessions. The texture profile analyses (TPA) were performed on cut cylinders of raw meat that underwent two cycles of 20% compression at 4 °C using a rheometer (Kinexus pro+, Malvern Instruments, Malvern, UK) and rSpace 1.61 software (Kinexus, Malvern, UK). Six parameters (springiness, hardness, cohesiveness, resilience, gumminess, and chewiness) were calculated from the force-deformation curve (Chinzorig and Hwang 2018; Texture technologies, 2022). de Huidobro et al. (2005) assert that TPA on raw meat can usefully predict the sensory properties of cooked meat. For each sample, raw portions of SV meat (1 cm wide and between 0.9 and 1.1 cm thick) underwent shear force analyses performed perpendicularly to fibres direction by the Warner–Braztler method (Instron 5944, Elancourt, France) using Bluehill 2 software (Instron, Elancourt, France). Mean shear force was computed from 20 shear force measurements per sample.

Statistical analyses

All statistical analysis was performed using R 4.0.5 software (R core Team 2021).

For each cattle category, we determined three ordered slaughter age classes based on slaughter age distribution to achieve similar-sized classes (Table 1).

ANOVA was used to test for the effects of cattle category and slaughter age on carcase and meat traits. As the animals came from different farms, the ANOVA tested the farm effect as a factor for all carcase and meat traits. We also used ANOVA models to test for slaughterhouse and operator effects on the carcase traits. If these effects were significant, a new ANOVA (mixed model) was performed using these effects as random effects. However, if these effects were not significant, a new ANOVA was performed but leaving out these factors. For the sensory data, ANOVA was performed using the individual data of each panellist. As the sensory data were repeated measures, the panellist effect was also considered as a random effect in the mixed models. A Tukey test was carried out when the cattle category effect was significant in ANOVA models.

The ‘agricolae’ package (de Mendiburu 2020) was used for ANOVA, and the ‘emmeans’ (Lenth 2021), ‘lmerTest’ (Kuznetsova et al. 2017), ‘multcompView’ (Graves et al. 2019), and ‘multcomp’ (Hothorn et al. 2008) packages were used for the mixed models followed by Tukey tests.

Results

Effect of cattle category on carcase traits

The confirmation of the young bull carcases was 11% and 13% higher compared to the heifer and the cull cow carcases, respectively (p < 0.001; Table 2). Young bulls had a significantly lower fat score, subcutaneous fat and intermuscular fat and significantly lower LM grain, RH grain, and overall meat grain compared to heifers and cull cows (p < 0.001). At the 6th rib level, carcases from young bulls also had a lower marbling score and whiter fat than carcases from the other categories. LM colour was 35% and 40% less red in young bulls compared to heifers and cull cows (p < 0.001), respectively. The nerve values evaluated at the 6th-rib level were significantly lower in young bull carcases, although the least-square mean values were similar between the three categories. Marbling score was 16% higher in heifers compared to cull cows (p < 0.001), whereas, the LM colour was significantly darker in cull cows compared to heifers. Cull cow carcases were 5% and 12% heavier than young bull and heifer carcases (p < 0.001), respectively.

Table 2. Effect of cattle category on carcase traits.

	Young bulls		Heifers		Cull cows		p Value
	LS mean	SE	LS mean	SE	LS mean	SE
Measurements performed on carcase
	n = 179		n = 171		n = 371
Cold weight (kg)	434^b	9.49	402^c	9.21	455^a	8.94	<0.001
Conformation score (scale from 1 to 15)	10.17^a	0.11	9.03^b	0.10	8.84^b	0.08	<0.001
Fatness score (scale from 1 to 5)	2.66^b	0.04	3.01^a	0.04	3.02^a	0.03	<0.001
	n = 174		n = 137		n = 300
Longissimus muscle seepage (scale from 1 to 5)	1.96	0.22	1.89	0.22	1.90	0.20	0.781
Subcutaneous fat (cm)	0.20^b	0.23	0.84^a	0.20	0.81^a	0.23	<0.001
Intermuscular fat (scale from 1 to 5)	0.98^b	0.19	2.11^a	0.19	2.09^a	0.18	<0.001
Nerves (scale from 1 to 5)	1.14^b	0.11	1.37^a	0.11	1.27^a	0.10	<0.001
Overall meat grain (scale from 1 to 5)	1.53^b	0.17	1.97^a	0.17	2.12^a	0.16	<0.001
Longissimus meat grain (scale from 1 to 5)	1.28^b	0.21	1.64^a	0.21	1.60^a	0.20	<0.001
Rhomboideus meat grain (scale from 1 to 5)	0.94^b	0.18	1.39^a	0.18	1.52^a	0.17	<0.001
Fat colour (scale from 0 to 9)	1.50^b	0.27	2.77^a	0.26	2.98^a	0.25	<0.001
Colour homogeneity of muscles at the 6th rib (scale from 1 to 4)	1.87	0.07	1.79	0.07	1.81	0.06	0.529
Longissimus colour (scale from 0 to 7)	2.82^c	0.29	4.31^b	0.28	4.74^a	0.27	<0.001
Longissimus marbling (scale from 0 to 6)	0.53^c	0.15	1.46^a	0.15	1.22^b	0.13	<0.001

LS mean: least-square mean; SE: standard error.

Effect of cattle category on the traits of the raw and cooked meat

There was only a cattle category effect on the parameters related to the colour and toughness of the raw meat (Table 3). After 14 days of ageing, the LM meat of young bulls was 6% and 10% lighter coloured compared to heifers and cull cows (p < 0.001), respectively. SV shear force was higher and the LM hardness was lower in meat from young bulls compared to heifers and cull cows. The LM meat of heifers had a 3% higher b* (yellowness) value compared to cull cows (p < 0.001). Heifers had 5% lighter-coloured raw LM meat and 8% higher SV meat shear force than cull cows. There was no cattle category effect on redness and the other texture parameters.

Table 3. Effect of cattle category on meat traits.

	Young bulls		Heifers		Cull cows		p Value
	LS mean	SE	LS mean	SE	LS mean	SE
Measurements performed on raw meat
Serratus ventralis muscle	n = 163		n = 162		n = 351
Shear force (N)	79.50^a	1.86	66.30^b	1.77	61.20^c	1.26	<0.001
Longissimus muscle
Colour descriptors	n = 166		n = 163		n = 354
L*	44.60^a	0.34	42.00^b	0.32	40.00^c	0.25	<0.001
a*	18.30	0.33	18.80	0.32	18.80	0.23	0.423
b*	12.00^ab	0.162	12.30^a	0.151	11.90^b	0.118	<0.001
Texture profile analyse	n = 126		n = 152		n = 305
Springiness	0.47	0.007	0.48	0.006	0.47	0.004	0.20
Hardness (N)	1.43^b	0.05	1.64^a	0.05	1.64^a	0.03	<0.001
Cohesiveness	2.34	0.15	2.28	0.13	2.34	0.10	0.907
Resilience	0.26	0.01	0.26	0.01	0.26	0.007	0.879
Gumminess	3.37	0.24	3.71	0.21	3.83	0.16	0.233
Chewiness	1.52	0.11	1.76	0.10	1.78	0.07	0.105
Measurements performed on cooked meat (longissimus muscle)
Sensory descriptors (scale from 0 to 10)	n = 166		n = 154		n = 345
Intensity of red	3.05^c	0.20	3.50^b	0.20	4.07^a	0.18	<0.001
Initial tenderness	6.13^b	0.15	6.46^a	0.15	5.99^b	0.14	<0.001
Overall tenderness	5.74^b	0.17	6.03^a	0.17	5.50^c	0.16	<0.001
Overall juiciness	4.34^c	0.18	4.59^b	0.180	4.78^a	0.17	<0.001
Presence of nerves	1.94^b	0.24	1.85^b	0.24	2.30^a	0.24	<0.001
Residue	2.95^b	0.20	3.17^a	0.20	3.18^a	0.19	0.003
Flavour intensity	5.70^b	0.14	5.88^a	0.14	5.93^a	0.13	<0.001
Fat taste	3.38^b	0.24	3.70^a	0.24	3.75^a	0.23	<0.001
Atypical flavour	1.01^a	0.17	0.80^b	0.17	0.95^a	0.17	0.011
Flavour persistence	4.68^b	0.19	4.89^a	0.19	4.97^a	0.18	<0.001

LS mean: least-square mean; SE: standard error.

L*: lightness; a*: redness; b*: yellowness.

The LM meat from young bulls had a significantly lower intensity of red, juiciness, flavour intensity, flavour persistence, and fat aroma than LM meat from the other categories (Table 3). Overall tenderness was 4% higher in meat from young bulls compared to cull cows. Heifer LM meat was more tender (initial and overall) than LM meat from the other categories and had the lowest atypical flavour. Cull cow LM meat had more nerves and was juicer and redder than that LM meat from the other categories.

Effect of slaughter age classes on young bulls

The young bulls slaughtered at over 18 months of age produced carcases with the highest 6^th-rib-level intermuscular fat. The slaughter age classes (≤16 months; >16 to 18 months; >18 months) had not effect on the other carcase and meat traits (Tables 4, 5).

Table 4. Effect of slaughter age classes on carcase in young bulls.

	Slaughter age classes (months)						p Value
	≤16		]16; 18]		>18
	LS mean	SE	LS mean	SE	LS mean	SE
Measurements performed on carcase
	n = 53		n = 87		n = 39
Cold weight (kg)	446	5.61	442	4.86	438	7.04	0.524
Conformation score (scale from 1 to 15)	10.30	0.20	10.10	0.18	10.20	0.23	0.330
Fatness score (scale from 1 to 5)	2.69	0.11	2.75	0.101	2.74	0.12	0.775
	n = 46		n = 86		n = 32
Longissimus muscle seepage (scale from 1 to 5)	2.05	0.36	2.23	0.36	1.84	0.42	0.267
Subcutaneous fat (cm)	0.53	0.28	0.60	0.27	0.83	0.34	0.560
Intermuscular fat (scale from 1 to 5)	1.25^b	0.13	1.28^b	0.13	1.60^a	0.17	0.021
Nerves (scale from 1 to 5)	1.52	0.18	1.52	0.18	1.60	0.20	0.813
Overall meat grain (scale from 1 to 5)	1.96	0.12	2.07	0.10	2.09	0.16	0.651
Longissimus meat grain (scale from 1 to 5)	1.91	0.24	1.64	0.24	1.55	0.28	0.076
Rhomboideus meat grain (scale from 1 to 5)	1.36	0.19	1.29	0.19	1.23	0.21	0.651
Fat colour (scale from 0 to 9)	1.44	0.18	1.29	0.17	1.17	0.20	0.242
Colour homogeneity of muscles at the 6th rib (scale from 1 to 4)	1.91	0.13	1.87	0.12	1.78	0.18	0.774
Longissimus colour (scale from 0 to 7)	2.13	0.32	2.05	0.32	2.59	0.37	0.058
Longissimus marbling (scale from 0 to 6)	0.77	0.18	0.55	0.17	0.64	0.20	0.177

LS mean: least-square mean; SE: standard error.

Table 5. Effect of slaughter age classes on meat traits in young bulls.

	Slaughter age classes (months)						p Value
	≤16		]16; 18]		>18
	LS mean	SE	LS mean	SE	LS mean	SE
Measurements performed on raw meat
Serratus ventralis muscle	n = 47		n = 83		n = 34
Shear force (N)	80.50	4.19	81.50	3.54	80.40	5.41	0.964
Longissimus muscle
Colour descriptors	n = 47		n = 84		n = 35
L*	45.30	0.64	45.20	0.56	43.70	0.79	0.107
a*	17.90	0.70	17.70	0.62	19.20	0.85	0.147
b*	12.20	0.30	12.00	0.28	11.9	0.35	0.470
Texture profile analyse	n = 30		n = 70		n = 19
Springiness	0.48	0.01	0.47	0.01	0.45	0.02	0.373
Hardness (N)	1.57	0.08	1.43	0.05	1.44	0.09	0.298
Cohesiveness	2.23	0.22	2.37	0.17	2.05	0.26	0.647
Resilience	0.25	0.01	0.26	0.01	0.23	0.02	0.649
Gumminess	3.55	0.38	3.35	0.28	2.97	0.45	0.678
Chewiness	1.65	0.17	1.51	0.11	1.32	0.20	0.494
Measurements performed on cooked meat (longissimus muscle)
Sensory descriptors (scale from 0 to 10)	n = 47		n = 84		n = 35
Intensity of red	3.02	0.23	2.95	0.20	3.31	0.26	0.366
Initial tenderness	6.27	0.17	6.06	0.15	6.10	0.17	0.240
Overall tenderness	5.86	0.18	5.64	0.16	5.72	0.19	0.228
Overall juiciness	4.27	0.21	4.34	0.19	4.53	0.22	0.292
Presence of nerves	1.88	0.24	2.06	0.23	2.06	0.25	0.244
Residue	2.85	0.20	3.00	0.19	2.83	0.21	0.282
Flavour intensity	5.60	0.15	5.74	0.14	5.83	0.16	0.145
Fat taste	3.47	0.25	3.50	0.25	3.51	0.26	0.965
Atypical flavour	1.17	0.22	1.26	0.21	0.94	0.24	0.071
Flavour persistence	4.62	0.21	4.74	0.20	4.71	0.21	0.529

LS mean: least-square mean; SE: standard error.

L*: lightness; a*: redness; b*: yellowness.

Effect of the slaughter age classes in heifers

In heifers, the slaughter age classes (<32 months; from 32 to 36 months; >36 months) mainly had an effect on carcase traits (Tables 6, 7). Heifers slaughtered after 32 months of age produced heavier carcases. Heifers slaughtered between 32 and 36 months produced carcases with 60% higher subcutaneous fat thickness compared to heifers slaughtered before 32 months (p < 0.009), and carcases with 23% more nerves, and 22% less dark LM (24h post-mortem) compared to heifers slaughtered after 36 months of age (p < 0.001). Heifers slaughtered between 32 and 36 months produced raw LM meat with 8.5% higher yellowness compared to heifers slaughtered after 36 months of age, and LM meat with 8% lower springiness compared to heifers slaughtered before 32 months of age (Table 7). Cooked LM meat of heifers slaughtered after 36 months had 15% higher nerve content than heifers slaughtered between 32 and 36 months.

Table 6. Effect of slaughter age classes on carcase traits in heifers.

	Slaughter age classes (months)						p Value
	<32		[32; 36]		>36
	LS mean	SE	LS mean	SE	LS mean	SE
Measurements performed on carcase
	n = 63		n = 58		n = 50
Cold weight (kg)	372^b	8.00	408^a	8.16	420^a	9.10	<0.001
Conformation score (scale from 1 to 15)	8.94	0.14	9.12	0.14	8.82	0.17	0.252
Fatness score (scale from 1 to 5)	2.98	0.05	2.98	0.05	2.92	0.06	0.582
	n = 45		n = 42		n = 42
Longissimus muscle seepage (scale from 1 to 5)	1.96	0.26	1.81	0.27	2.21	0.29	0.229
Subcutaneous fat (cm)	0.51^b	0.27	1.28^a	0.29	0.79^ab	0.29	0.009
Intermuscular fat (scale from 1 to 5)	2.14	0.28	1.99	0.28	2.06	0.30	0.814
Nerves (scale from 1 to 5)	1.41^ab	0.19	1.65^a	0.19	1.27^b	0.20	0.001
Overall meat grain (scale from 1 to 5)	2.11	0.22	2.18	0.22	2.09	0.24	0.850
Longissimus meat grain (scale from 1 to 5)	1.79	0.30	1.85	0.30	1.54	0.31	0.246
Rhomboideus meat grain (scale from 1 to 5)	1.44	0.26	1.50	0.26	1.48	0.27	0.937
Fat colour (scale from 0 to 9)	2.51	0.45	2.61	0.45	3.07	0.46	0.080
Colour homogeneity of muscles at the 6th rib (scale from 1 to 4)	1.80	0.09	1.81	0.09	1.83	0.09	0.966
Longissimus colour (scale from 0 to 7)	4.29^ab	0.42	3.63^b	0.43	4.65^a	0.43	0.001
Longissimus marbling (scale from 0 to 6)	1.35	0.25	1.62	0.26	1.42	0.27	0.428

LS mean: least-square mean; SE: standard error.

Table 7. Effect of slaughter age classes on meat traits in heifers.

	Slaughter age classes (months)						p Value
	<32		[32; 36]		>36
	LS mean	SE	LS mean	SE	LS mean	SE
Measurements performed on raw meat
Serratus ventralis muscle	n = 63		n = 54		n = 45
Shear force (N)	66.31	2.55	70.33	2.19	62.71	2.61	0.118
Longissimus muscle
Colour descriptors	n = 63		n = 54		n = 46
L*	41.90	0.56	41.60	0.56	41.90	0.69	0.855
a*	19.20	0.59	18.00	0.60	19.80	0.74	0.068
b*	12.40^ab	0.26	12.90^a	0.26	11.80^b	0.32	0.004
Texture profile analyse	n = 63		n = 50		n = 39
Springiness	0.50^a	0.01	0.46^b	0.01	0.48^ab	0.01	0.030
Hardness (N)	1.69	0.07	1.63	0.06	1.63	0.12	0.812
Cohesiveness	2.09	0.12	2.08	0.18	2.58	0.26	0.115
Resilience	0.24	0.01	0.24	0.01	0.27	0.02	0.150
Gumminess	3.58	0.26	3.38	0.29	4.10	0.43	0.313
Chewiness	1.76	0.13	1.55	0.14	1.93	0.20	0.256
Measurements performed on cooked meat (longissimus muscle)	n = 63		n = 46		n = 46
Sensory descriptors (scale from 0 to 10)
Intensity of red	3.43	0.22	3.53	0.24	3.71	0.24	0.464
Initial tenderness	6.37	0.17	6.53	0.18	6.16	0.19	0.104
Overall tenderness	5.92	0.20	6.11	0.21	5.68	0.22	0.082
Overall juiciness	4.59	0.20	4.70	0.21	4.62	0.20	0.766
Presence of nerves	1.88^ab	0.24	1.76^b	0.24	2.08^a	0.24	0.005
Residue	3.27	0.22	3.11	0.22	3.31	0.23	0.365
Flavour intensity	5.81	0.15	6.00	0.15	5.82	0.15	0.089
Fat taste	3.67	0.25	3.77	0.25	3.54	0.25	0.197
Atypical flavour	0.80	0.18	0.75	0.18	0.77	0.19	0.829
Flavour persistence	4.88	0.20	4.96	0.20	4.84	0.20	0.403

LS mean: least-square mean; SE: standard error.

L*: lightness; a*: redness; b*: yellowness.

Effect of slaughter age classes in cull cows

In cull cows, there were very relatively few effects of slaughter age classes (<6 years; from 6 to 9 years]; >9 years) on carcase and meat traits (Tables 8, 9). Cull cows slaughtered between 6 and 9 years produced the heaviest carcases, and carcases with 3% higher fat scores and 13% yellower fat than cull cows slaughtered at earlier than 6 years. Cull cows slaughtered at above 6 years gave the darkest LM meat and highest RH meat grain at 24h post-mortem. Cull cows slaughtered at earlier than 6 years of age produced the lightest-coloured raw LM meat after 14 days of ageing.

Table 8. Effect of slaughter age classes on carcase traits in cull cows.

	Slaughter age classes (years)						p Value
	<6		[6; 9]		>9
	LS mean	SE	LS mean	SE	LS mean	SE
Measurements performed on carcase
	n = 156		n = 122		n = 93
Cold weight (kg)	446^b	5.96	469^a	6.19	461^a	6.33	<0.001
Conformation score (scale from 1 to 15)	8.96	0.14	8.89	0.15	8.73	0.15	0.101
Fatness score (scale from 1 to 5)	2.97^b	0.03	3.06^a	0.04	2.98^ab	0.04	0.050
	n = 134		n = 103		n = 63
Longissimus muscle seepage (scale from 1 to 5)	1.92	0.23	2.12	0.23	1.85	0.24	0.061
Subcutaneous fat (cm)	0.77	0.23	0.96	0.23	0.70	0.25	0.474
Intermuscular fat (scale from 1 to 5)	2.10	0.23	2.10	0.23	2.05	0.24	0.894
Nerves (scale from 1 to 5)	1.19	0.10	1.15	0.10	1.23	0.10	0.086
Overall meat grain (scale from 1 to 5)	2.04	0.20	2.23	0.20	2.16	0.20	0.069
Longissimus meat grain (scale from 1 to 5)	1.65	0.25	1.65	0.25	1.56	0.26	0.497
Rhomboideus meat grain (scale from 1 to 5)	1.37^b	0.23	1.65^a	0.23	1.61^a	0.23	<0.001
Fat colour (scale from 0 to 9)	2.73^b	0.32	3.15^a	0.32	3.10^ab	0.33	0.005
Colour homogeneity of muscles at the 6th rib (scale from 1 to 4)	1.82	0.07	1.80	0.08	1.73	0.09	0.583
Longissimus colour (scale from 0 to 7)	4.15^b	0.25	4.76^a	0.25	5.05^a	0.27	<0.001
Longissimus marbling (scale from 0 to 6)	1.12	0.16	1.28	0.16	1.21	0.17	0.297

LS mean: least-square mean; SE: standard error.

Table 9. Effect of slaughter age classes on meat traits in cull cows.

	Slaughter age classes (years)						p Value
	<6		[6; 9]		>9
	LS mean	SE	LS mean	SE	LS mean	SE
Measurements performed on raw meat
Serratus ventralis muscle	n = 149		n = 113		n = 89
Shear force (N)	62.40	1.65	61.00	1.80	58.30	2.00	0.216
Longissimus muscle
Colour descriptors	n = 150		n = 114		n = 90
L*	40.50^a	0.29	39.50^b	0.31	39.40^b	0.34	0.002
a*	18.90	0.32	18.80	0.35	18.90	0.39	0.924
b*	12.00	0.15	11.80	0.16	11.70	0.17	0.228
Texture profile analyse	n = 128		n = 99		n = 78
Springiness	0.47	0.01	0.47	0.01	0.48	0.01	0.580
Hardness (N)	1.65	0.04	1.61	0.04	1.61	0.05	0.765
Cohesiveness	2.23	0.14	2.45	0.15	2.27	0.17	0.465
Resilience	0.25	0.01	0.27	0.01	0.26	0.01	0.357
Gumminess	3.81	0.23	3.99	0.23	3.71	0.26	0.723
Chewiness	1.75	0.12	1.88	0.10	1.72	0.12	0.580
Measurements performed on cooked meat (longissimus muscle)	n = 147		n = 111		n = 87
Sensory descriptors (scale from 0 to 10)
Intensity of red	4.03	0.22	4.04	0.23	4.25	0.24	0.492
Initial tenderness	6.04	0.15	6.00	0.16	6.00	0.16	0.904
Overall tenderness	5.58	0.18	5.53	0.18	5.49	0.19	0.708
Overall juiciness	4.76	0.18	4.78	0.18	4.79	0.18	0.930
Presence of nerves	2.26	0.25	2.32	0.25	2.27	0.25	0.768
Residue	3.14	0.20	3.23	0.20	3.08	0.21	0.269
Flavour intensity	5.93	0.14	5.95	0.14	5.95	0.14	0.904
Fat taste	3.74	0.24	3.75	0.24	3.83	0.24	0.502
Atypical flavour	0.93	0.17	0.87	0.17	0.87	0.17	0.624
Flavour persistence	4.96	0.19	5.03	0.19	4.95	0.19	0.424

LS mean: least-square mean; SE: standard error.

L*: lightness; a*: redness; b*: yellowness.

Discussion

In France, suckler-cattle breeds have been bred exclusively for meat. The young bulls must be slaughtered at before 24 months of age and the heifers are mainly slaughtered between 26 and 33 months. For meat produced to quality-label standards, the heifers can be slaughtered at around 36 months. In this system, after the period of calf production (up to around 8 years), the cows are fattened and slaughtered for meat. Market demand differs according to cattle category. The meat from young bulls is sold to the export market, mainly in northern Europe or North Africa whereas suckler-breed heifers and cull cows are mainly sold in traditional butcher’s shops or mass-retail supermarkets.

According to our results, young bull carcases had a different set of traits to heifer and cull cow carcases. Young bull carcases were characterised by an intermediate weight, higher conformation, leaner content (fatness, marbling, subcutaneous and intermuscular fat) and smoother meat grain (overall, LM, and RH), and had lighter-yellow fat and lighter-red LM.

Our results are in agreement with Gagaoua et al. (2018) who showed lighter carcases for young bulls than cull cows in the Charolais breed. Like here, many other studies have found that young bulls give heavier carcases than heifers in other breeds (pure dairy and/or crossed breeds; Steen and Kilpatrick 1995; Bures and Barton 2012; Blanco et al. 2020; Lebedová et al. 2022). This study also confirmed the results of many other studies that have found that young bulls produce carcases with higher conformation scores than heifers (Steen and Kilpatrick 1995; Węglarz 2010a; Blanco et al. 2020) and cull cows (Fiems et al. 2003; Gagaoua et al. 2018). The hormonal secretion caused by anabolic hormones produced by the testicles is an element explaining the capacity of young bulls to deposit muscle quickly compared to female (Lee et al. 1990). This study reinforced results from previous reports that the young bull carcases are leaner (e.g. fatness, marbling, intermuscular) than heifer carcases (Węglarz 2010b; Bures and Barton 2012; Blanco et al. 2020; Lebedová et al. 2022). Sex hormones had effects on hyperplasia and hypertrophy of adipocytes explaining for example, the marbling differences between heifers and young bulls (Nguyen et al. 2021). However, Fiems et al. (2003) reported higher carcase fatness in young bulls than in cull cows whereas Węglarz (2010a) found no category effect of the category (young bulls vs. cull cows) on carcase fat. It was possible that the precocity of breeds and the fattening management also explain the different results obtained in these studies.

In accordance with our results, some studies have observed that the LM was less red in young bulls than in heifers (Węglarz 2010a) and cull cows (Fiems et al. 2003; Gagaoua et al. 2018). According to Clinquart et al. (2022), the pigment content increases more quickly with age in females than in males. Here, young bulls were slaughtered at a younger age than heifers and cull cows, which is in line with Clinquart et al. (2022). However, other studies failed to find any differences in LM redness between young bulls and heifers (Bures and Barton 2012; Lebedová et al. 2022). These divergent results may be explained by different breeds and slaughter ages between studies, as both these factors have an effect on meat colour (Clinquart et al. 2022).

The meat grain variation between the three cattle categories studied here could be explained by the type and cross-section area of the muscle fibres, which differ according to the sex and age of the animal (Picard and Gagaoua 2020).

This study found that meat from young bulls had the lowest scores on sensory descriptors compared to meat from heifers or cull cows, except for overall tenderness and atypical flavour. Moreover, meat from young bulls scored higher on atypical flavour compared to meat from heifers. Many other studies on other breeds and with 7 day-ageing have shown that compared to heifers, young bulls produced LM meat that is tougher, less juicy, and has less flavour intensity (Bures and Barton 2012; Lebedová et al. 2022). However, other authors did not find significant differences between young bulls and heifers in LM tenderness (Węglarz 2010a; Blanco et al. 2020), juiciness and beef flavour intensity (Bures and Barton 2012; Blanco et al. 2020). Blanco et al. (2020) reported a higher rancid odour for LM meat of young bulls than heifers, which could explain the differences in atypical flavour score observed between these categories. In accordance with Blanco et al. (2020) and Lebedová et al. (2022), cattle category (young bulls vs. heifers) had no effect on residue of chewing and the presence of nerves.

Our results converge with many other studies showing that heifers produced lighter carcases and a less-red LM at 24h post-mortem compared to cull cows (Cabaraux et al. 2004; Węglarz 2010b; Pacheco et al. 2011). Contrary to our results, Pacheco et al. (2011) observed that the marbling score in the Charolais breed was lower in heifers than cull cows. Note that Pacheco et al. (2011) studied heifers that were younger than here and were bred in another country which, could explain the differences. Shackelford et al. (1995) did not observe any category effect on marbling scores in many breeds and cross-breeds.

Few published works have investigated the cattle category effect (heifers vs. cull cows) on the sensory properties of cooked LM meat. Our results converge with Shackelford et al. (1995) and Lucero-Borja et al. (2014) who observed that heifers produced a more tender LM meat than cull cows. However, other authors have found no cattle category effect (heifers vs. cull cows) on LM meat tenderness (Fiems et al. 2003; Cabaraux et al. 2004; Pacheco et al. 2011). Moreover, and contrary to our results, other authors have found no category effect on the juiciness and flavour of LM meat (Shackelford et al. 1995; Pacheco et al. 2011; Lucero-Borja et al. 2014).

For all three cattle categories, the carcase traits were more sensitive to variation in slaughter age than the meat traits. Slaughter age had different patterns of effect on carcase and meat traits according to cattle category.

When young bulls were slaughtered at an older age, only intermuscular fat was higher and there was no age effect on meat traits. Other authors also observed an increase in fat (e.g. fatness, internal fat and/or marbling) with increasing slaughter age of young bulls (Bures and Barton 2012; do Prado et al. 2015). These differences in results showed that the carcase fatness cannot be explain only by the slaughter age. The interactions with other factors as the genetic of animal, rearing management can contribute to explain the fat (inter and intra) level in carcases. In agreement with our findings, Bures and Barton (2012) and Dransfield et al. (2003) showed no effect of slaughter age on LM meat redness and sensory descriptors (overall tenderness, residue, juiciness, and flavour), respectively.

Here, heifer slaughter age has an effect on four carcase and two meat traits. There is very little literature on the slaughter age effect in heifers on carcase and meat traits. Studies in younger heifers than those studied here (between 14 and 18 months or between 18 and 22 months) found that the late-slaughtered heifers produced heavier carcases without difference in conformation scores (Ahnstrom et al. 2012; Bures and Barton 2012). Our results were in accordance with the results of these studies. According to Soulat et al. (2018b), slaughtering heifers at a late age increased the chances of yielding heavier carcases with a higher conformation score and dressing percentage. However, similar carcase traits (e.g. weight, conformation score, and dressing percentage) could be obtained from different rearing managements including different slaughter ages (Soulat et al. 2020). Bures and Barton (2012) showed an increase in subcutaneous fat thickness when heifers were slaughtered older (14 vs. 18 months). This result could explain the increase in subcutaneous fat thickness observed here between heifers slaughtered at earlier than 32 months of age versus between 32 and 36 months. However, here, the highest-age-class heifers did not have the highest subcutaneous fat thickness. In our study, at 24h post-mortem, LM colour did not increase linearly with slaughter age. It is possible that other rearing factors or combinations of rearing factors could explain why some carcase traits did not increase linearly with slaughter age. In young heifers (< 22 months), Ahnstrom et al. (2012) observed an increase in LM redness with late slaughter, whereas Bures and Barton (2012) found no slaughter age effect on this colour parameter. Breed and the rearing management used in our study may explain that the slaughter age had a different effect on LM colour compared to the results of other studies. Concerning cooked meat, contrary to our results, Ahnstrom et al. (2012) and Bures and Barton (2012) found an increase in overall tenderness in meat from later-slaughtered heifers. However, both these studies used younger heifers and a different breed from here. Other studies consistently find breed effect on beef sensory properties (Schnell et al. 1997; Chambaz et al. 2003; Bures and Barton 2012). According to Soulat et al. (2018b), an increase in heifer slaughter age increased the chances of yielding more tender, juicer, and more flavour-intense LM meat. However, our results showed that the oldest-slaughtered heifers did not produce the most tender LM meat, which could be explained by different rearing managements (Soulat et al. 2020).

The cull cow carcase weight increased until 6 years then the slaughter age did not affect the carcase weight, in accordance with Muller et al. (1992) who observed no effect of the slaughter age on carcase weight in Charolais cull cows slaughtered after 8 years of age. In France, for a few years, the slaughterhouses expect lighter carcases. The cull cows produce heavier carcases compared to young animals (young bulls and heifers). The market demand could penalise the sale of the carcases from cull cows. That could be an element to explain that the carcase weight does not increase linearly with the slaughter age in cull cows. In this study, the fat score was significantly affected by slaughter age, but the differences were very low. Many studies have failed to show a slaughter age effect on different fat-related carcase traits (e.g. marbling, fatness, fat proportion; Muller et al. 1992; Jurie et al. 2006; Galli et al. 2008 ). Contrary to our results, Sawyer et al. (2004) observed a decrease in fatness in British breeds when cull cows were late-slaughtered. In France, the fat score target is 3 according to the EUROP system, whatever the cattle category and the slaughter age. This aim leads to limiting the slaughter age effect on the fat score level. Here, RH meat grain was more granular when the cull cows were slaughtered at a later age. This result could be explained by the impact of age on the muscle fibre size and type (Picard and Gagaoua 2020; Clinquart et al. 2022). Contrary to our results, Galli et al. (2008) reported no slaughter age effect on fat and lean colour at 24h post-mortem in Hereford cull cows. In heifers, Soulat et al. (2020) displayed a rearing management effect on LM colour (at 24h post-mortem) which could explain the observed differences. In agreement with Muller et al. (1992) and Dransfield et al. (2003), our results confirmed that the slaughter age of the Charolais cull cows had no effect on the sensory properties of LM meat.

Conclusion

The aim of this work was to study the effects of cattle category and slaughter age in Charolais breed. This study updates the knowledge of these effects. Heifers produced carcases and meat with higher quality than young bulls and cull cows. The slaughter age had very little effect on meat (raw and cooked) traits whatever the cattle category. Based on our results, young bulls can be slaughtered at different ages without negative impacts on carcase and meat traits. In rearing systems, the farmer grouped calving, this would allow slaughters and sales to be spread across the year, and enable cattle producers to manage slaughter periods according to market demand and inputs costs for example. For heifers, except for the carcase weight, the carcase and meat properties were not significantly different when the heifers were slaughtered earlier than 32 months or later than 36 months. Heifers slaughtered at after 32 months of age yielded heavier carcases. For cull cows, as slaughter age had little effects on meat quality, a slaughter at above 6 years yielded heavier carcases. However, if the target is to produce light carcases with a smoother meat grain, then a better strategy is to slaughter cull cows before 6 years of age. This strategy would involve increasing the herd turnover rate, which in turn would very likely have an impact on the economic efficiency of the production system. Therefore, we advise farmers to adopt a global farm-system-scale approach.

Authors’ Contributions

Julien Soulat: Methodology, Software, Validation, Formal analysis, Investigation, Resources, Data curation, Writing - original draft, Writing – review & Editing, Visualisation, Project administration

Brigitte Picard: Conceptualisation, Writing – review & Editing, Supervision, Project administration, Funding acquisition

Valérie Monteils: Conceptualisation, Writing – review & Editing, Supervision, Project administration, Funding acquisition

Acknowledgments

The authors would first like to thank the staff of the four breeding cooperatives (FEDER, SICABA, SICAGIEB and SICAREV) for helping us to select the cattle producers and the staff of the five slaughterhouses (Puigrenier, SICABA, SICAREV, SOCOPA, and Viandes de Bresse) for the achievement of the measure on carcasses and the meat sampling. The authors thank also the INRAE staff for the meat samples collection and transport, for the meat sample preparation and rheological analyses (shear force), and VetAgro Sup staff for colour, sensorial and rheological (texture) analyses. Finally, the authors would like thank the other partners implicated in the development of the ProBA (produce suckler cattle delivering the goods of the slaughterers in the region Auvergne-Rhône-Alpes) project: ARIA Auvergne-Rhône-Alpes, la Chambre Régionale d’Agriculture Auvergne-Rhône-Alpes, and La Cooperation Agricole Auvergne-Rhône-Alpes

Disclosure statement

All authors report no conflicts of interests.

Data availability statement

The data that support the findings of this study are available from the corresponding author, [VM], upon reasonable request.

Additional information

Funding

This study was financed by the French ministry of agriculture and food, the region Auvergne-Rhône-Alpes (convention Massif central) and the French government IDEX-ISITE initiative 16-IDEX-0001 (CAP 20-25).