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There are a number of differences in the meat and carcass quality traits between pasture-raised and concentrate-raised lambs that may further be used to trace back the diet, but the extent to which these differences are modulated by pasture-finishing duration is unknown. In this study, we investigated the changes in longissimus thoracis et lumborum muscle and fat spectrocolorimetric properties, and dorsal fat firmness, in lambs switched from a stall-fed concentrate-based diet to grazing on lucerne for various durations (0, 21, 42, 63 days) pre-slaughter. Stall-fed lambs from the different treatment groups were managed in a single group and lucerne pasture-finished lambs from the different treatment groups also co-grazed in a single group. The level of concentrate fed to stall-fed lambs was adjusted to maintain a similar mean pattern of growth between lucerne pasture-fed and stall-fed lambs. The trial used a total of 141 lambs over two successive years. Dorsal fat was firmer in lambs finished on lucerne pasture, even for the shortest finishing duration (21 days), the difference being of commercial importance. Dorsal fat colour and carotenoid content showed changes at 21 days on lucerne pasture but did not change further for longer lucerne pasture-finishing durations. In contrast, perirenal fat lightness, yellowness, chroma and carotenoid content showed changes at 21 days on lucerne pasture and increased consistently with lucerne pasture-finishing duration. Although these changes in fat spectrocolorimetric properties were not, or barely, visible to the naked eye, they could be of interest for authenticating the duration of lucerne pasture-finishing. Muscle redness increased consistently with the duration of lucerne pasture-finishing, the change becoming significant from 42 days on lucerne pasture and being visible to the naked eye. We observed a consistent decrease in muscle hue angle and perirenal fat redness and a consistent increase in perirenal fat hue angle with lucerne pasture-finishing duration, but these changes only became significant from 63 days on lucerne pasture. The pattern of change in the lamb carcass and meat quality traits measured according to lucerne pasture-finishing duration therefore varied between the tissues and quality traits.

ABSTRACT: Many studies over the last 30 years have shown the effects of farming practices on milk compounds. Combinations of practices may have antagonistic or synergistic effects on milk compounds, but these combination effects remain underinvestigated. Research needs to focus on overall intrinsic milk quality (including sensory, technological, health, and nutritional dimensions) and identify the combinations that can optimize it. The aim of this study was to identify which combinations of farming practices achieved the best scores for sensory, technological, health, and nutritional dimensions and for overall intrinsic milk quality. Ninety-nine private farms were visited once each to sample their bulk tank milk and survey their farming practices. The surveyed practices concerned herd characteristics, feeding management, housing conditions, and milking and milk storage conditions on the day of test. Analyses of bulk tank milk were designed to evaluate the overall intrinsic quality of the milk for 2 target products: raw milk cheese and semi-skimmed UHT milk. Regression trees were then used to identify the combinations of farming practices that achieved the best scores on each dimension and on overall intrinsic quality of the milk. Breed and diet (type of forage) were the most influential factors for sensory and health dimensions and for technological and nutritional dimension scores, respectively, in the cheese assessment. Overall cheese quality was highly positively correlated with these 4 dimension scores. Therefore, breed and diet emerged as the most influential practices in the regression tree for overall cheese quality. However, the combinations of practices that resulted in the best quality scores differed according to dimension studied and product targeted. This suggests that advice on farming practices to improve intrinsic milk quality needs to be adapted according to the end-purpose of the collected milk. This innovative approach combining on-farm data and regression trees provides farm managers with a valuable and practical tool to prioritize practices in terms of their role in shaping milk quality, and to identify the combinations of practices that promote good milk quality and practice thresholds or modalities needed to achieve it.

There are time-tested assessments for the environmental and economic aspects of sustainability. Its societal aspect has mainly been approached through the assessment of animal welfare. However, the intrinsic quality of milk is seldom taken into account. We developed a participatory construction method for the overall assessment of intrinsic milk quality in its different dimensions (sensory, technological, nutritional and health), according to the fate of the raw milk. Two assessment models were developed, for semi-skimmed standardized ultra-high temperature (UHT) milk and for pressed uncooked non-standardized raw milk cheese. They were constructed by a participatory approach involving experts in the dairy sector with the aim to obtain a diagnostic tool that could be used in the field to help farmers to manage the quality of their milk (by prioritizing improvements on major problems). They were shaped from prerequisite specifications (limited costs and time of application, desire to obtain a transparent tool with all the steps kept visible) and current technical and scientific knowledge. They were based on indicators obtained from raw bulk tank milk analyses (30 for UHT milk and 50 for cheese assessments), which were then aggregated into criteria, principles, dimensions and overall intrinsic quality at farm level. The assessment models had parts in common, for example, same four dimensions, common indicators for health and nutritional dimensions. They also had process-specific features: units chosen, criteria, indicators and weightings in relation to the final product specifications. For instance, sensory and technological dimensions are more complex and preponderant in the cheese assessment (three principles for cheese vs one for UHT milk in both dimensions). Another example is the lack of microbial pathogens (as potential health risk for consumer) in the UHT milk assessment because of pasteurization. The assessment models then underwent a sensitivity analysis and an application in 30 farms in indoor and grazing periods to finally obtain overall UHT milk and cheese quality scores at a 1-year level. The tool was found to be applicable at farm level. However, we observed low overall quality scores with a narrow dispersion, characteristic of a severe evaluation. Even so, the assessment models showed up seasonal differences of the UHT milk and cheese quality at both overall and dimensional levels. In the light of new scientific knowledge and future quality objectives, these are adaptable to other dairy products allowing for their specific features.

There are a number of differences in the meat and carcass quality traits between pasture-raised and concentrate-raised lambs that may further be used to trace back the diet, but the extent to which these differences are modulated by pasture-finishing duration is unknown. In this study, we investigated the changes in longissimus thoracis et lumborum muscle and fat spectrocolorimetric properties, and dorsal fat firmness, in lambs switched from a stall-fed concentrate-based diet to grazing on lucerne for various durations (0, 21, 42, 63 days) pre-slaughter. Stall-fed lambs from the different treatment groups were managed in a single group and lucerne pasture-finished lambs from the different treatment groups also co-grazed in a single group. The level of concentrate fed to stall-fed lambs was adjusted to maintain a similar mean pattern of growth between lucerne pasture-fed and stall-fed lambs. The trial used a total of 141 lambs over two successive years. Dorsal fat was firmer in lambs finished on lucerne pasture, even for the shortest finishing duration (21 days), the difference being of commercial importance. Dorsal fat colour and carotenoid content showed changes at 21 days on lucerne pasture but did not change further for longer lucerne pasture-finishing durations. In contrast, perirenal fat lightness, yellowness, chroma and carotenoid content showed changes at 21 days on lucerne pasture and increased consistently with lucerne pasture-finishing duration. Although these changes in fat spectrocolorimetric properties were not, or barely, visible to the naked eye, they could be of interest for authenticating the duration of lucerne pasture-finishing. Muscle redness increased consistently with the duration of lucerne pasture-finishing, the change becoming significant from 42 days on lucerne pasture and being visible to the naked eye. We observed a consistent decrease in muscle hue angle and perirenal fat redness and a consistent increase in perirenal fat hue angle with lucerne pasture-finishing duration, but these changes only became significant from 63 days on lucerne pasture. The pattern of change in the lamb carcass and meat quality traits measured according to lucerne pasture-finishing duration therefore varied between the tissues and quality traits., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Spectral analysis of meat combined with chemometric analysis has been identified as a promising tool for authenticating livestock-animal diets. The objectives of this study were (i) to determine whether the visible-NIR spectrum of perirenal adipose tissue (PAT) and caudal adipose tissue (CAT) can reliably discriminate lambs pasture-finished for different durations before slaughter, and (ii) to analyze the kinetics of appearance and stabilization of the visible-NIR spectrum-based pasture signature in PAT and CAT. Four groups of 50-55 lambs were used over three years: lambs finished on lucerne pasture for 0 (L0, concentrate-fed in stall), 21 (L21), 42 (L42) and 63 (L63) days before slaughter. Partial least squares discriminant analysis was applied on PAT or CAT visible-NIR spectra to discriminate the groups. No one adipose tissue reliably discriminated the four groups, with less than 62 % lambs correctly classified. However, visible-NIR spectroscopy was able to discriminate stall-fed (L0) from pasture-finished (L21 + L42 + L63) lambs, with an accuracy of 93.8 % and 87.5 % lambs correctly classified based on PAT and CAT spectra, respectively. The lucerne pasture fingerprint (or signature) on visible-NIR spectrum appeared between 0 and 42 days in more than 95 % of lambs. It stabilized between 42 and 63 days in CAT, but had not stabilized within the range of grazing durations pre-slaughter explored in PAT. Further research into shorter and longer pasture-finishing durations could help determine more precisely the time required for the pasture signature to appear and stabilize in animal tissues., Competing Interests: Declaration of competing interest None to declare., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Pasture-based livestock systems are considered environmentally-sustainable and welfare-friendly farming systems that can meet consumer demand for good-quality produce. However, trust in products labelled as 'grass-fed' depends on the ability to reliably authenticate pasture origin. The two objectives of this study were (i) to test the ability of visible spectroscopy combined with discriminant analysis on lamb perirenal fat (PF), dorsal fat (DF) and longissimus thoracis et lumborum muscle to discriminate different durations of pasture-finishing; and (ii) to determine the timing of appearance of the pasture signature and its stabilization in these tissues. Four groups of 35 lambs were used over two years, i.e. lambs fed concentrate in-stall (L0) and lambs grazing alfalfa for 21d (L21), 42d (L42) and 63d (L63) before slaughter. No one tissue satisfactorily discriminated the four treatment groups, with ≤75% of lambs correctly classified. However, visible spectroscopy discriminated L0 from L21 + L42 + L63 lambs with an accuracy of 92.8%, 92.0%, and 85.3% lambs correctly classified on PF, DF and muscle, respectively, and discriminated L0 + L21 from L42 + L63 lambs with an accuracy of 90.1%, 76.5% and 92.3% on PF, DF and muscle, respectively. The pasture fingerprint or signature on the spectrum appeared in most lambs between 0 and 21d in PF and DF and between 0 and 42d in muscle. Pasture signature gradually stabilized with increasing time on pasture but was not entirely stabilized in any tissue within the range of grazing durations explored. These promising results need to be confirmed on larger datasets with different breeds and grazing conditions., Competing Interests: Declaration of Competing Interest None to declare., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Meat from lambs fattened on alfalfa is at risk of excessive pastoral flavours due to high levels of in-fat volatile indolic compounds (especially, skatole). Skatole has also been identified as a potential marker of interest for authenticating pasture-fed lamb meat. Here, we investigated the change in skatole and indole concentrations in kidney fat from lambs switched from an indoor-fed concentrate based diet to outdoor alfalfa grazing for various durations (0, 21, 42, 63 days) before slaughter. The study used a total of 219 lambs over 3 consecutive years. Kidney-fat skatole and indole concentrations increased from as early as 21 days on alfalfa, and then reached a plateau. Similarly, the proportion of lambs that had a kidney fat-skatole concentration above 0.15 μg/g liquid fat, a value that has been established as a sensory rejection threshold for pork, increased significantly from as early as 21 days on alfalfa and then reached a plateau. This value was reached or exceeded in a significant proportion of lambs fattened on alfalfa pastures (45.1%). However, skatole was not detected in kidney fat from 20 out of 164 alfalfa-fattened lambs (i.e., 12.2%) but was detected in 15 out of 55 concentrate-fed lambs (i.e., 27.3%). We thus conclude that while skatole content in kidney fat can inform on dietary changes made shortly before slaughter, it does not have the discrimination power needed to reliably authenticate pasture-fed lamb meat, let alone duration of finishing on pasture., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

There are time-tested assessments for the environmental and economic aspects of sustainability. Its societal aspect has mainly been approached through the assessment of animal welfare. However, the intrinsic quality of milk is seldom taken into account. We developed a participatory construction method for the overall assessment of intrinsic milk quality in its different dimensions (sensory, technological, nutritional and health), according to the fate of the raw milk. Two assessment models were developed, for semi-skimmed standardized ultra-high temperature (UHT) milk and for pressed uncooked non-standardized raw milk cheese. They were constructed by a participatory approach involving experts in the dairy sector with the aim to obtain a diagnostic tool that could be used in the field to help farmers to manage the quality of their milk (by prioritizing improvements on major problems). They were shaped from prerequisite specifications (limited costs and time of application, desire to obtain a transparent tool with all the steps kept visible) and current technical and scientific knowledge. They were based on indicators obtained from raw bulk tank milk analyses (30 for UHT milk and 50 for cheese assessments), which were then aggregated into criteria, principles, dimensions and overall intrinsic quality at farm level. The assessment models had parts in common, for example, same four dimensions, common indicators for health and nutritional dimensions. They also had process-specific features: units chosen, criteria, indicators and weightings in relation to the final product specifications. For instance, sensory and technological dimensions are more complex and preponderant in the cheese assessment (three principles for cheese vs one for UHT milk in both dimensions). Another example is the lack of microbial pathogens (as potential health risk for consumer) in the UHT milk assessment because of pasteurization. The assessment models then underwent a sensitivity analysis and an application in 30 farms in indoor and grazing periods to finally obtain overall UHT milk and cheese quality scores at a 1-year level. The tool was found to be applicable at farm level. However, we observed low overall quality scores with a narrow dispersion, characteristic of a severe evaluation. Even so, the assessment models showed up seasonal differences of the UHT milk and cheese quality at both overall and dimensional levels. In the light of new scientific knowledge and future quality objectives, these are adaptable to other dairy products allowing for their specific features., (Copyright © 2021 The Author(s). Published by Elsevier B.V. All rights reserved.)