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Abstract Background The most used protein sources in ruminant nutrition are considered as having negative impacts in terms of environmental sustainability and competition with human nutrition. Therefore, the investigation of alternative and sustainable feedstuffs is becoming a priority in ruminant production systems. Results This trial was designed to evaluate eight full-fat insect meals ( Acheta domesticus – ACD; Alphitobius diaperinus – ALD; Blatta lateralis – BL; Gryllus bimaculatus – GB; Grylloides sygillatus – GS; Hermetia illucens – HI; Musca domestica – MD; and Tenebrio molitor – TM) as potential protein and lipid sources in ruminant nutrition. Fermentation parameters and fatty acids (FA) of rumen digesta after 24-h in vitro ruminal incubation of the tested insect meals were measured and compared with those of three plant-based meals (soybean meal, rapeseed meal and sunflower meal) and fishmeal (FM). Similarly to FM, the insect meals led to a significantly lower total gas production (on average, 1.75 vs. 4.64 mmol/g dry matter—DM), methane production (on average, 0.33 vs. 0.91 mmol/g DM), volatile FA production (on average, 4.12 vs. 7.53 mmol/g DM), and in vitro organic matter disappearance (on average, 0.32 vs. 0.59 g/g) than those observed for the plant meals. The insect meals also led to lower ammonia of rumen fluid, when expressed as a proportion of total N (on average, 0.74 vs. 0.52 for the plant and insect meals, respectively), which could be an advantage provided that intestinal digestibility is high. Differences in ruminal fermentation parameters between the insect meals could be partially explained by their chitin, crude protein and ether extract contents, as well as by their FA profile. In particular, high content of polyunsaturated FA, or C12:0 (in HI), seems to partially inhibit the ruminal fermentations. Conclusions The tested full-fat insect meals appear to be potentially an interesting protein and lipid source for ruminants, alternative to the less sustainable and commonly used ones of plant origin. The FA profile of the rumen digesta of ACD, ALD, GB, GS and TM, being rich in n-6 polyunsaturated FA, could be interesting to improve the quality of ruminant-derived food products.

This study explored the effects of hazelnut skin (HZN) supplementation in the diets of pregnant ewes on colostrum and milk composition, as well as on the serum levels of immune-related proteins in lambs and their growth performance. HZN, an agro-industrial by-product rich in bioactive compounds such as polyphenols and unsaturated fatty acids (FA), was evaluated for its potential as a sustainable feed ingredient. During the peripartum period, ewes were divided into two groups of eight, fed the same hay-based diet but differing for the concentrate composition: a cereal mix including rumen-protected palm oil or HZN. The intake of major nutrients or milk yield did not differ between groups. However, the HZN group exhibited an enhanced fatty acid profile in their colostrum and milk, including increased levels of unsaturated FA. The HZN lambs displayed higher levels of immune-related proteins (albumin and γ-globulins) in their blood. Nonetheless, no significant differences were observed in lamb growth performance. The study highlights the potential of HZN to enhance the nutritional and immunological quality of milk and colostrum without negatively impacting growth performance. This suggests that HZN could serve as a sustainable feed ingredient potentially improving neonatal immunity while contributing to waste valorisation in livestock production systems.

Background Insect meals have been identified as innovative and sustainable feedstuffs that could be used in ruminant nutrition. However, current research on the effects that their processing may have on rumen digestibility and fatty acid (FA) biohydrogenation is scant. This trial aims to investigate the effects (i) of drying temperature of full-fat Hermetia illucens (HI) and Tenebrio molitor (TM) meals, and (ii) of residual ether extract (EE) content of defatted HI and TM meals, on their fermentation characteristics and FA of rumen digesta after 24-h in vitro rumen incubation. Methods The tested full-fat meals included four HI and four TM meals obtained applying drying temperatures ranging from 30 °C to 70 °C, while the tested defatted meals consisted of five HI and two TM meals containing a residual EE content ranging from 4.7 to 19.7 g EE/100 g dry matter (DM). The applied statistical models (GLM ANOVA) tested the effects of insect species, drying temperature (full-fat meals) or EE content (defatted meals), and their interaction. Results Drying temperature had minor effects on in vitro ruminal digestibility and FA profile of rumen digesta. Irrespective of insect species, increasing the drying temperature led to a reduction of in vitro degradation of proteins from insect meals, as outlined by the significant decrease in ammonia production (−0.009 mmol/g DM and −0.126 g/100 g total N for each additional 1 °C). Irrespective of insect species, defatting increased total gas, volatile fatty acids (VFA) and CH 4 productions, and the proportions of total saturated and branched-chain FA in rumen digesta (+0.038 mmol/g DM, +0.063 mmol/g DM, +12.9 µmol/g DM, +0.18 g/100 g FA, and +0.19 g/100 g FA for each reduced 1 g EE/100 g DM, respectively), and reduced the proportion of total PUFA (−0.12 g/100 g FA). Conclusions The applied drying temperatures of full-fat insect meals are too low to exert impactful effects on rumen digestibility and FA biohydrogenation. Fat lowered fermentation activity, probably because of an inhibitory effect on rumen microbiota. The increased ruminal digestibility of defatted insect meals suggests that they can be more suitable to be used in ruminant nutrition than full-fat ones.

The dairy industry could make use of sustainable alternatives to conventional palm fat in ruminant nutrition. Insect-derived lipids, particularly the oil extracted from Hermetia illucens larvae ( H. illucens oil, HIO), show promise as an environmentally sustainable substitute. However, its effects on metabolic pathways and potential to replace fractionated palm oil (FPO) in lactating dairy cow diets remain insufficiently characterized. This study investigated the effects of HIO on the rumen and serum metabolome of lactating dairy cows. Twenty-six Valdostana Red Pied cows (parity = 3 ± 1.9; days in milk = 68 ± 27.5 d; BW = 556 ± 49.5 kg) were randomly assigned to receive either HIO or FPO (3% of the concentrate on as fed basis) for 50 days. Rumen fluid and serum samples were collected at the beginning (d 0, the day before starting the experimental diets administration) and end of the trial (d 50) for subsequent metabolomic analysis using liquid chromatography-mass spectrometry. A total of 7,590 rumen fluid and 8,061 serum features were detected, with 687 and 689 metabolites annotated, respectively. Principal component analysis (PCA) revealed stronger temporal than treatment effects. Serum metabolome showed slightly more pronounced responses to dietary HIO inclusion than rumen fluid, with 61 and 64 differential metabolites identified between HIO and FPO groups in rumen and serum, respectively. The pathway enrichment analysis based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) database revealed that HIO inclusion modulated metabolic pathways mainly related to amino acid and lipid metabolism. Specifically, metabolites such as N-acetyl-L-glutamate, imidazolepropionic acid, sulfate, and polyunsaturated fatty acids (e.g., stearidonic acid and dihomo-γ-linolenic acid) were significantly altered following HIO inclusion. In contrast, pathways related to glycolysis and starch metabolism remained largely unaffected. No adverse metabolic effects associated with the tested HIO inclusion level were detected. HIO may be a metabolically safe and more sustainable alternative to FPO in dairy cow diets at the given inclusion rate, without evidence of disrupting metabolic homeostasis.

Background Scant information is currently available on the use of insect oils in ruminant diets. Insect oils could be used as alternatives to certain conventional plant lipid sources that are considered no longer sustainable. This trial aims at evaluating the effects of the dietary inclusion of Hermetia illucens oil (HIO) vs. hydrogenated palm fat (HPF) on digestive parameters, oxidative stress, and milk production performance of dairy cows. Results Twenty-six Valdostana Red Pied cows were randomly divided into two groups and fed with hay ad libitum and a concentrate containing 3% (as fed) of either HPF or HIO. The trial lasted 50 d, including two weeks of diet adaptation. Individual feed intake and milk yield were monitored three and four times a week, respectively. Fecal samples were collected at the end (d 50) of the trial to determine total-tract nutrients apparent digestibility. Individual blood samples were collected to evaluate blood plasma metabolites (d 0 and d 50) and oxidative stress parameters (d 0, d 26 and d 50). Milk samples were collected at d 0, d 14, d 26, d 38 and d 50 for chemical composition analysis. Feed efficiency was estimated through feed conversion ratio and residual feed intake (RFI). Data were analyzed by SAS software using a mixed model. The diet had no effect on nutrients intake and apparent total-tract digestibility. However, the dietary inclusion of HIO led to higher milk production (+ 0.82 kg/cow/d; P  < 0.05) and slightly lower RFI (−0.008; P  < 0.001) when compared to the HPF diet. Milk composition and the nutritional metabolic status of the cows remained unaffected by diet. Serum antioxidant capacity was comparable between the two groups, while lower derivatives of reactive oxygen metabolite concentrations were observed in the HIO-fed cows when compared to the HPF-fed ones (−37.13 Carratelli Units; P  < 0.001). Conclusions The dietary inclusion of HIO instead of HPF did not negatively affect feed palatability and total-tract apparent digestibility of nutrients in dairy cows. Furthermore, it increased feed efficiency by supporting a higher milk production together with an improved antioxidant status. The results suggest that HIO could be an eligible option as an innovative energy source for dairy cows.

This study aimed to study the relationship between milk quality for cheese manufacturing and farm’s environmental impacts in grass-based mountain systems. Beforehand, the multi-criteria evaluation methodology proposed by Botreau et al. and Rey-Cadilhac et al. was adapted to a routine use. Milk quality scores were constructed by weighing traits possibly predicted by spectroscopic analyses currently available in milk labs into 4 dimensions: health, nutritional, technological and sensory. Environmental impact scores were constructed by combining 6 indicators of the CAP'2ER® software in 5 dimensions: greenhouse gas emissions, eutrophication, air acidification, consumption of space and non-renewable energies and ecosystem biodiversity. The study sample included 15 dairy farms located in the French Massif Central mountains. An analysis of variance was carried out to study the effect of system’s types on milk quality and environmental impact scores. A principal component analysis was used to study the relationship between milk quality and environmental impact dimensions scores. No correlation has been established between overall milk quality and overall environmental impact scores. High scores for the nutritional and biodiversity dimensions and low scores for the resource consumption dimension, were associated with farming practices such as a high proportion of grasslands in the usable agricultural area, low stocking rate and low productivity per cow. This demonstrates the importance of defining specific priority objectives, on a farm-by-farm basis, in order to drive changes in agricultural practices. The multi-criteria evaluation model tested here appeared sensitive, but it needs to be tested on a larger scale and in different contexts.

This work aimed to investigate the effect of energy nature (lipids vs. carbohydrates) on enteric methane emission (eCH4) and performance in dairy cows fed grass silage-based diets. Eight multiparous Holstein cows were used in a 4 × 4 Latin square design, with 4 experimental periods of 28 days each. Cows were fed with 4 iso-energetic diets based on grass silage and supplemented with different levels of rapeseed oil (RO) (0, 1.5, 3.0, 4.5% of dietary dry matter (DM), Control, RO-low, RO-medium, RO-high diets, respectively) in substitution of starch from concentrate. Dairy performance, total-tract digestibility, and rumen parameters were measured when animals were in individual respiration chambers for quantifying eCH4. Intake of DM decreased with RO-high compared to other diets. Methane emissions were lowered similarly with all diets containing RO compared to Control (on average, -19% in g/d, −13% in g/kg DMI, −21% in g/kg milk). Ruminal propionate proportion was higher, whereas that of butyrate was lower with RO-high compared to the other diets. Milk yield was higher with RO-low and RO-medium, and was lower for RO-high compared to Control. Milk C16:0 concentration was lower, and C18:1c9, C18:1t11, and other rumen biohydrogenation intermediate concentrations were higher with diets containing RO compared to Control. The shift from the C18:1t11 to C18:1t10 biohydrogenation pathway is in agreement with the milk fat depression observed with RO-medium and RO-high. The inclusion of RO at 1.5% was the best compromise between eCH4, feed efficiency, and milk nutritional quality in cows fed grass silage-based diets.

Rearing dairy calves with their mothers could teach them how to graze, optimizing grass use, and improving their welfare and performance. We tested the short-term effects of dam-calf contact experience on grazing and social behavior of weaned calves, monitored over seven days for their first post-weaning grazing experience. “Dam” (D) calves were reared and grazed with their mothers until weaning. “Mixed” calves (M) were separated from their mothers after 4 ± 0.5 weeks, they experienced dam-calf contact, but not grazing. “Standard” (S) calves had never experienced either dam-calf contact (separated at birth) or grazing. Each group grazed an equivalent pasture plot offering heterogeneous herbage. Scan sampling of calves' activities was performed every 5 min, 6 h per day, on Days 0, 1, 2, 3, and 7. Daily, the time when calves started grazing after introduction to pasture, and the number and duration of their grazing cycles were measured. Daily activities were differentiated into ingestion, rumination, and idling. The proportion of time that calves spent grouped with other individuals or isolated, and standing or lying were recorded. When grazing, their bites were characterized by botanical family group, height of the selected bite and vegetation status. Individual average daily gains from the 2-week periods before and after grazing were calculated, and were equivalent between groups (313 ± 71 g/d). On Day 0, D-calves started grazing immediately (1 ± 4.1 min), unlike M- and S-calves (39 ± 4.1 and 23 ± 4.1 min), and D-calves grazed patches of dry grass 21.7 times less than M-calves and 16.9 times less than S-calves. Dry herbage patch preference and grazing start time differences disappeared on Day 1. Calves spent the same time ingesting and idling, but M-calves spent on average 1.6 times less ruminating than D- or S-calves. The D-calves showed grazing behavior similar to that of adult cows, selecting grasses throughout pasture utilization, although legumes and forbs were present in the grazed layer. On the contrary, M- and S-calves did not express any specific preference. The S-calves spent more time isolated but had more positive reciprocal interactions than the calves in the other groups.

In the mountains, autochthonous and robust breeds are often used to valorize biodiverse grasslands. Along with their lower nutrient requirements, compared to specialized dairy breeds, they are expected to be better adapted to complex environments and valorize grasslands into dairy products of high quality. Therefore, the aim of the present study was to investigate the grazing selection of three contrasting dairy breeds on a biodiverse mountain pasture, and its consequences on milk fatty acid (FA) profile and prevalence of individual terpenes. A dual-purpose breed from the Italian Alps, the Valdostana Red Pied (Va), was compared to Montbéliardes (Mo), more specialized in milk production, and the highly specialized Holsteins (Ho). Diet selection was measured by scan-sampling, calculating selectivity indexes, and collecting simulated bites during two consecutive days in June (end of first grazing cycle) and July (second grazing cycle). Milk samples were collected at each milking during these experimental periods. Yield of milk and its fat and protein contents were measured. Milk FA and terpenes were analyzed by gas chromatographic methods. We tested the effects of breed, period and their interaction in a repeated mixed model, and calculated Pearson's correlations between behavioral data and milk FA as well as terpenes. The Va grazed less mature vegetation than Ho, but this difference was not sufficient to lead to a major breed effect on milk FA profile and prevalence of terpenes. However, the proportion of α-linolenic acid (C18:3 n-3) was always higher in the milk fat of Va than Ho (Mo were intermediary), but this without any correlation to grazing selection. This could be a consequence from a different metabolism concerning ruminal biohydrogenation, but must be further investigated. Finally, we confirmed previous studies that highlighted a link between milk quality and cows' grazing behavior, but here without differences among breeds. All cows adapted their behavior to the herbage evolution during the season, leading to higher proportions of unsaturated FA in July than June milks. Our study suggests that under mountain grazing conditions (biodiverse pasture and cows in late lactation), milk quality depends more on herbage composition than on cow breed.