Increasing intake of essential fatty acids from milk replacer benefits performance, immune responses, and health of preweaned Holstein calves

Long Chain Fatty Acids Mediate Hepatic Metabolic Flux in Preruminating Dairy Calves Fed Flaxseed Oil, High Oleic Soybean Oil, or Milk Fat

Nutrition and physiological state affect hepatic metabolism. Our objective was to determine if feeding flaxseed oil (∼50% C18:3n-3 cis), high oleic soybean oil (∼70% C18:1 cis-9), or milk fat (∼50% C16:0) alters hepatic expression of PC, PCK1, and PCK2 and the flow of carbons from propionate and pyruvate into the TCA cycle in preruminating calves. Male Holstein calves (n = 40) were assigned to a diet of skim milk with either: 3% milk fat (MF; n = 8), 3% flaxseed oil (Flax; n = 8), 3% high oleic soybean oil (HOSO; n = 8), 1.5% MF + 1.5% high oleic soybean oil (MF-HOSO; n = 8), or 1.5% MF + 1.5% flaxseed oil (MF-Flax; n = 8) from d 14 to d 21 postnatal. At d 21 postnatal, a liver biopsy was taken for gene expression and metabolic flux analysis. Liver explants were incubated in [U-13C] propionate and [U-13C] pyruvate to trace carbon flux through TCA cycle intermediates or with [U-14C] lactate, [1-14C] palmitic acid, or [2-14C] propionate to quantify substrate oxidation to CO2 and acid soluble products. Compared with other treatments, plasma C18:3n-3 cis was 10 times higher and C18:1 cis-9 was 3 times lower in both flax (Flax and MF-Flax) treatments. PC, PCK1, and PCK2 expression and flux of [U-13C] pyruvate as well as [U-13C] propionate were not different between treatments. PC expression was negatively correlated with the enrichment of citrate M+5 and malate M+3, and PCK2 was negatively correlated with citrate M+5, suggesting that when expression of these enzymes is increased, carbon from pyruvate enters the TCA cycle via PC mediated carboxylation, and then OAA is converted to phosphoenolpyruvate via PCK2. Acid soluble product formation and PC expression were reduced in HOSO (MF-HOSO and HOSO) treatments compared with flax (MF-Flax and Flax), indicating that fatty acids regulate PC expression and carbon flux, but that fatty acid flux control points are not connected to PC, PCK1, or PCK2. In conclusion, fatty acids regulate hepatic expression of PC, PCK1, and PCK2, and carbon flux, but the point of control is distinct.

Fat composition of milk replacer influences postprandial and oxidative metabolisms in dairy calves fed twice daily

Milk replacers (MR) for calves contain alternative fat sources as substitute for milk fat. This substitution leads to differences in fat properties, such as the fatty acid profile and the triglyceride structure. This study evaluated how fat composition in MR affects gastrointestinal health, blood redox parameters, and postprandial metabolism in calves fed twice daily. Forty-five individually housed male Holstein-Friesian calves (2.3 ± 0.85 d of age) were assigned to 1 of 15 blocks based on the age and the day of arrival. Within each block, calves were randomly assigned to 1 of 3 experimental diets and received their respective diet from arrival until 35 d after arrival. The 3 experimental diets (n = 15 per treatment group) consisted of an MR with a blend of vegetable fats containing rapeseed and coconut (VG), an MR with only animal fats from lard and dairy cream (AN), and an MR containing a mixture of animal and vegetable fats including lard and coconut (MX). The fatty acid profile of each MR was formulated to resemble that of bovine milk fat while using only 2 fat sources. All MR were isoenergetic, with 30% fat (% DM), 24% crude protein, and 36% lactose. Chopped straw and water were available ad libitum from arrival onward but no starter feed was provided. Daily milk allowances were 6.0 L from d 1 to 5, 7.0 L from d 6 to 9, and 8.0 L from d 10 to 35, divided into 2 equal meals and prepared at 135 g/L (13.5% solids). Fecal appearance was scored daily; calves were weighed and blood was drawn on arrival and weekly thereafter. Urine and feces were collected over a 24-h period at wk 3 and 5 to determine apparent total-tract digestibility and assess gastrointestinal permeability using indigestible markers. Postprandial metabolism was evaluated at wk 4 by sequential blood sampling over 7.5 h, and the abomasal emptying rate was determined by acetaminophen appearance in blood. Fat composition in MR did not affect growth, MR intake, gastrointestinal permeability, nor nutrient digestibility. The percentage of calves with abnormal fecal scores was lower at wk 2 after arrival in calves fed VG than MX, whereas AN did not differ from the other treatments. Calves fed AN and MX had higher thiobarbituric acid reactive substances measured in serum than VG, whereas plasma ferric-reducing ability was greater in calves fed MX than VG. Postprandial acetaminophen concentrations did not differ across treatment groups, but the area under the curve was smaller in calves fed VG than in the other 2 treatments, which is indicative of a slower abomasal emptying. Postprandial serum triglyceride concentration was greater in calves fed AN than VG, whereas MX did not differ from the other treatments. Based on these outcomes, all 3 fat blends can be considered suitable for inclusion in MR for calves.

Exploring the Rumen Microbiota and Serum Metabolite Profile of Hainan Black Goats with Different Body Weights before Weaning

The critical role of the rumen microbiota in the growth performance of livestock is recognized, yet its significance in determining the body weight of goat kids before weaning remains less understood. To bridge this gap, our study delved into the rumen microbiota, serum metabolome, rumen fermentation, and rumen development in goat kids with contrasting body weights before weaning. We selected 10 goat kids from a cohort of 100, categorized into low body weight (LBW, 5.56 ± 0.98 kg) and high body weight (HBW, 9.51 ± 1.01 kg) groups. The study involved sampling rumen contents, tissues, and serum from these animals. Our findings showed that the HBW goat kids showed significant enrichment of VFA-producing bacteria, particularly microbiota taxa within the Prevotellaceae genera (UCG-001, UCG-003, and UCG-004) and the Prevotella genus. This enrichment correlated with elevated acetate and butyrate levels, positively influencing rumen papillae development. Additionally, it was associated with elevated serum levels of glucose, total cholesterol, and triglycerides. The serum metabonomic analysis revealed marked differences in fatty acid metabolism between the LBW and HBW groups, particularly in encompassing oleic acid and both long-chain saturated and polyunsaturated fatty acids. Further correlational analysis underscored a significant positive association between Prevotellaceae_UCG-001 and specific lipids, such as phosphatidylcholine (PC) (22:5/18:3) and PC (20:3/20:1) (r > 0.60, p < 0.05). In summary, this study underscores the pivotal role of the rumen microbiota in goat kids' weight and its correlation with specific serum metabolites. These insights could pave the way for innovative strategies aimed at improving animal body weight through targeted modulation of the rumen microbiota.

N-3 Polyunsaturated Fatty Acids as a Nutritional Support of the Reproductive and Immune System of Cattle-A Review

This paper focuses on the role of n-3 fatty acids as a nutrient crucial to the proper functioning of reproductive and immune systems in cattle. Emphasis was placed on the connection between maternal and offspring immunity. The summarized results confirm the importance and beneficial effect of n-3 family fatty acids on ruminant organisms. Meanwhile, dietary n-3 fatty acids supplementation, especially during the critical first week for dairy cows experiencing their peripartum period, in general, is expected to enhance reproductive performance, and the impact of its supplementation appears to be dependent on body condition scores of cows during the drying period, the severity of the negative energy balance, and the amount of fat in the basic feed ration. An unbalanced, insufficient, or excessive fatty acid supplementation of cows' diets in the early stages of pregnancy (during fetus development) may affect both the metabolic and nutritional programming of the offspring. The presence of the polyunsaturated fatty acids of the n-3 family in the calves' ration affects not only the performance of calves but also the immune response, antioxidant status, and overall metabolism of the future adult cow.

Effects of fat source in calf starter on growth performance, blood fatty acid profiles, and inflammatory markers during cold season

This study was conducted to investigate the effects of supplementation of different fat sources in calf starters on growth performance, health, blood fatty acid profiles, and inflammatory markers during the cold season in dairy calves. A total of 48 Holstein calves (24 males and 24 females) were randomly assigned to 1 of 4 starter diets throughout the experiment (d 3 to 65): (1) no supplemented fat (CON), (2) 3% calcium-salts of soybean oil (Ca-SBO), (3) 3% calcium-salts of fish oil (Ca-FO), and (4) 3% mixture of Ca-SBO and Ca-FO (1.5% each, DM basis; MIX). Calves were given free access to starter feed and water and were raised individually in pens from 3 to 65 d of age. Calves fed Ca-SBO consumed a greater proportion of n-6 FA, while calves fed Ca-FO consumed a greater level of n-3 FA compared to the other dietary treatments. Fat supplementation increased the intake of linoleic acid, the major n-6 FA, with the greater intake observed in the Ca-SBO group compared to the other dietary treatments. Calves fed the Ca-FO and MIX diets consumed more long-chain n-3 FA than the other diets. In addition, calves fed Ca-SBO and Ca-FO diets consumed more starter feed and total dry matter than calves fed MIX and CON throughout the experiment (d 3 to 65). Calves fed Ca-FO had higher average daily gain throughout the trial (d 3 to 65) than the other treatment groups. Of all treatment groups, calves fed Ca-FO achieved the highest final body weight and showed the greatest feed efficiency. Random forest analysis revealed that eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and arachidonic acid were the serum levels of FA most affected by the diets. The principal component analysis of blood FA profile, blood parameters, and inflammatory markers showed distinct differences between dietary treatments. Calves fed Ca-SBO had higher plasma concentrations of linoleic acid, while calves fed Ca-FO had higher plasma concentrations of long-chain n-3 polyunsaturated fatty acids (PUFA), such as EPA, docosapentaenoic acid (DPA), and DHA than the other treatment groups. Plasma inflammatory markers were lower in calves fed Ca-FO and higher in calves fed CON than in the other treatment groups. The Ca-FO group had lower levels of inflammatory markers, including serum amyloid A, tumor necrosis factor-alpha, Interferon-γ, haptoglobin, and interleukin-6 compared to the other experimental treatments. Also, the blood malondialdehyde levels, an indicator of oxidative stress, were lower in calves fed Ca-FO compared with calves fed the other treatment diets. In conclusion, the performance of preweaned dairy calves can be improved by adding fat to their starter feed under cold conditions. Overall, the type of fat in milk may affect growth and inflammation of dairy calves before weaning under cold conditions, with n-3 FA (Ca-FO) promoting growth and reducing inflammation more effectively than n-6 FA (Ca-SBO).

Gastrointestinal structure and function of preweaning dairy calves fed a whole milk powder or a milk replacer high in fat

The composition of milk replacer (MR) for calves greatly differs from that of bovine whole milk, which may affect gastrointestinal development of young calves. In this light, the objective of the current study was to compare gastrointestinal tract structure and function in response to feeding liquid diets having a same macronutrient profile (e.g., fat, lactose, protein) in calves in the first month of life. Eighteen male Holstein calves (46.6 ± 5.12 kg; 1.4 ± 0.50 d of age at arrival; mean ± standard deviation) were housed individually. Upon arrival, calves were blocked based on age and arrival day, and, within a block, calves were randomly assigned to either a whole milk powder (WP; 26% fat, DM basis, n = 9) or a MR high in fat (25% fat, n = 9) fed 3.0 L 3 times daily (9 L total per day) at 135 g/L through teat buckets. On d 21, gut permeability was assessed with indigestible permeability markers [chromium (Cr)-EDTA, lactulose, and d-mannitol]. On d 32 after arrival, calves were slaughtered. The weight of the total forestomach without contents was greater in WP-fed calves. Furthermore, duodenum and ileum weights were similar between treatment groups, but jejunum and total small intestine weights were greater in WP-fed calves. The surface area of the duodenum and ileum did not differ between treatment groups, but the surface area of the proximal jejunum was greater in calves fed WP. Urinary lactulose and Cr-EDTA recoveries were greater in calves fed WP in the first 6 h post marker administration. Tight junction protein gene expression in the proximal jejunum or ileum did not differ between treatments. The free fatty acid and phospholipid fatty acid profiles in the proximal jejunum and ileum differed between treatments and generally reflected the fatty acid profile of each liquid diet. Feeding WP or MR altered gut permeability and fatty acid composition of the gastrointestinal tract and further investigation are needed to understand the biological relevance of the observed differences.

Effects of Coconut Oil and Palm Oil on Growth, Rumen Microbiota, and Fatty Acid Profile of Suckling Calves

This study aimed to evaluate the effects of coconut oil and palm oil in milk replacer (MR) on the growth performance, blood lipids, rumen fermentation, rumen microbiota, and fatty acid profile of hepatic and muscle of suckling calves. Thirty-six Holstein male calves were randomly assigned to three treatments. Three milk replacers containing different fat sources were as follows: control group (CON, milk fat), coconut oil group (CCO, coconut oil powder as fat), and palm oil group (PLO, palm oil powder as fat). Calves were weighed and blood sampled at 14, 28, 42, and 56 days old, respectively, and the feed intake and fecal score were recorded daily. Fat sources in milk replacers had no effects on body weight, ADG, DMI, fecal score, or days of abnormal fecal in suckling calves among the three groups, while the PLO group tended to decrease starter intake compared with the other groups. Serum concentrations of TC, HDL-C, LDL-C, and VLDL-C in the CCO group increased compared with those of the CON group. Palm oil also decreased the serum GLU concentration of calves but had no effects on serum lipids compared with milk fat. Coconut oil or palm oil had no effects on rumen fermentation, rumen chyme enzyme activity, rumen bacterial community richness and diversity, and dominant phyla and genera when compared with milk fat. However, compared with the CON group, the CCO group increased the proportion of MCFAs and n-6 PUFAs, and decreased the proportion of UFAs and MUFAs in liver tissue, while the PLO group increased the proportion of PUFAs and decreased the proportion of n-3 PUFAs in liver tissue. In addition, compared with the CON group, the CCO group increased the proportion of MCFAs, and decreased the proportion of UFAs and n-3 PUFAs in longissimus dorsi, while the PLO group increased the proportion of PUFAs and decreased the proportion of n-3 PUFAs in longissimus dorsi. In conclusion, compared with milk fat, coconut oil or palm oil in MR had no effects on growth performance, rumen fermentation, and rumen microflora but significantly increased serum lipids concentration and changed some proportions of MCFAs and PUFAs in liver and longissimus dorsi in suckling calves. These results indicate that coconut oil or palm oil as the sole fat source for MRs has no adverse effect on calf rumen fermentation and rumen microbiota but has a detrimental effect on n-3 PUFAs deposition in the liver and longissimus dorsi muscle.

Effects of linseed oil supplementation in Holstein dairy calves received starters based on either corn or barley grain on growth performance and immune response

This study evaluated the effects of linseed oil (LO) and two-grain sources on growth performance, microbial protein yield (MPY), blood metabolites, and inflammatory markers in Holstein dairy calves. Forty-eight 3-day-old dairy calves (24 males and 24 females) with starting BW of 40.3 ± 1.6 kg were allocated in a completely randomised block design with a 2 × 2 factorial arrangement as follows; (1) Corn grain (CG) with no LO supplementation (CG-NLO), (2) CG with 2.5% LO supplementation (CG-LO), (3) Barley grain (BG) with no LO supplementation (BG-NLO), and (4) BG with 2.5% LO supplementation (BG-LO). The calves were weaned on d 59 but the study lasted for 14 days after weaning (Day 73 of experiment). The results showed that starter feed intake was influenced neither by grain source nor linseed oil. However, average daily gain, BW, hip height, and MPY were improved in calves received BG compared to CG diets. Linseed oil supplementation had no significant effects on growth performance and MPY. During preweaning period, calves fed BG-LO had the greatest feed efficiency and the highest wither height. However, the greatest tumour necrosis factor and serum amyloid A were observed in BG-NLO. Despite, LO supplementation did not influence growth performance of animals per se; however, it reduced circulating inflammatory markers in calves during preweaning period. Based on this study condition, BG is more favourable than CG in dairy calves from the daily gain and microbial protein synthesis perspectives, and supplementing the starters with n-3 FA can be strategy to improve immune performance of calves fed barley-based starter diets.

Supplementation of n-3 fatty acid and ruminal undegradable to degradable protein ratio in young lambs raised under heat condition: effects on growth performance and urinary purine derivatives

The present study evaluated the effect of supplementation alpha-linolenic fatty acid source (ALA) with different rumen undegradable to degradable protein ratios [low ratio (LR) = 26:74; high ratio (HR) = 36:64 based on CP%] on growth performance, nutrient digestibility, fecal score, animal feeding behavior, and urinary purine derivatives (PD) in young lambs during hot season. Forty 10-day-old lambs (averaging body weight of 7.9 ± 0.8 kg) were used in a completely randomized block design with a 2 × 2 factorial arrangement as following treatments (10 lambs/treatment): (1) no n-3 FA supplementation with LR diet (NALA-LR), (2) no ALA supplementation with HR diet (NALA-HR), (3) supplementation of ALA with LR diet (ALA-LR), and (4) supplementation of ALA with HR diet (ALA-HR). Results showed that ALA supplementation slightly increased feed efficiency (FE; tendency, P = 0.076), improved fecal score (P = 0.045), and reduced rectal temperature (tendency, P = 0.064) during pre-weaning period. The HR diets improved average daily gain (ADG; P < 0.01), wither height (post-weaning; P = 0.015), and final BW (P = 0.048) compared with LR diets. The greatest ADG (pre-weaning; P = 0.012), structural growth, and the lowest urinary nitrogen exertion (P = 0.043) were found in the ALA-HR treatment. No change was found for ruminal fermentation, nutrient digestibility, and animal behavior in lambs fed different experimental treatments. In summary, results indicated that concurrent feeding of ALA and high dietary RUP:RDP ratio can be recommendable that is likely due to more efficient nitrogen utilization when young lambs are raised during hot season. HIGHLIGHTS: • The interaction of n-3 FA and nitrogen was evaluated in pre-weaning lambs raised under heat condition. • Supplementation of n-3 FA increased FE and improved fecal score in heat-exposed lambs during pre-weaning period. • The high RUP:RDP ratio improved skeletal growth during post-weaning period. • Concurrent feeding of n-3 FA and high dietary RUP:RDP ratio is recommendable in young lambs raised during hot season.

Fatty acid profile characterization in colostrum, transition milk, and mature milk of primi- and multiparous cows during the first week of lactation

The specific fatty acid (FA) profile of colostrum may indicate a biological requirement for neonatal calves. The objective of this study was to characterize the FA profile and yields in colostrum, transition milk, and mature milk in primiparous (PP) and multiparous (MP) cows. Colostrum was milked from 10 PP and 10 MP Holstein cows fed the same pre- and postpartum rations. Milkings (M) 2 to 5 and 12 were respectively termed transition and mature milk. Overall, short-chain FA (C4:0 and C6:0) were 61 and 50% lower in colostrum than mature milk, respectively. A parity by milking interaction was also present, with higher C4:0 for PP cows at M2 and for MP cows at M12. Additionally, higher concentrations of C6:0 were present for PP cows at M2 through M4 and for MP cows at M12. Palmitic (C16:0) and myristic (C14:0) acids were 38% and 19% higher in colostrum than mature milk, respectively. However, total saturated FA remained relatively stable. Branched-chain FA were 13% lower in colostrum than mature milk and higher in PP than MP cows throughout the milking period. The proportion of trans-monounsaturated FA (MUFA) was 72% higher in PP cows throughout the milking period, as well as 13% lower in colostrum than mature milk. In contrast, cis-MUFA and total MUFA were not affected by milking nor parity. Linoleic acid (LA) was 25% higher in colostrum than transition and mature milks, but α-linolenic acid (ALA) did not differ. Consequently, the ratio of LA to ALA was 29% higher in colostrum than mature milk and 33% higher in MP cows. Linoleic acid was also 15% higher in MP cows, whereas ALA was 15% higher in PP cows. Conjugated linoleic acid (CLA, cis-9,trans-11) was 2.7-fold higher in PP cows, and no differences between colostrum and mature milk were detected. Overall, polyunsaturated FA (PUFA) from the n-6 and n-3 series were over 40% higher in colostrum compared with transition and mature milk. Milking by parity interactions were present for arachidonic acid (ARA), eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), docosahexaenoic acid (DHA), and total n-3 PUFA, translating to higher proportions in PP cows in M1 to M3, whereas proportions remained relatively stable throughout the milking period in MP cows. Despite increasing milk yields throughout the subsequent milkings, higher yields of EPA, ARA, DPA, and DHA were present in colostrum than in mature milk. Greater proportions and yields of n-3 and n-6 FA in colostrum may translate to specific requirements for newborn calves. Differences were also observed between PP and MP cows and may reflect different nutrient requirements and partitioning.

Defining Fatty Acid Changes Linked to Rumen Development, Weaning and Growth in Holstein-Friesian Heifers

After birth, as effectively monogastric animals, calves undergo substantial physiological changes to become ruminants by 3 months of age and reach sexual maturity at approximately 15 months of age. Herein, we assess longitudinal metabolomic changes in Holstein-Friesian (HF) heifers from birth until sexual maturity during this developmental process. Sera from 20 healthy, HF heifers were sampled biweekly from 2 weeks of age until 13 months of age and then monthly until 19 months of age. Sera were assessed using flow infusion electrospray high-resolution mass spectrometry (FIE-HRMS) on a Q Exactive hybrid quadrupole-Orbitrap mass spectrometer for high-throughput, sensitive, non-targeted metabolite fingerprinting. Partial least squares discriminant analysis (PLS-DA) and unsupervised hierarchical clustering analysis (HCA) of the derived metabolomes indicated changes detectable in heifers’ sera over time. Time series analyses identified 30 metabolites that could be related to rumen development and weaning at ~3 months of age. Further time series analysis identified 40 metabolites that could be correlated with growth. These findings highlight the role of acetic acid and 3-phenylpropionate (3-PP) in rumen development and growth, suggest that weaning induces elevated levels of fatty acyls in response to a post-weaning stress-induced innate immune response and demonstrate the utilization of fatty acyls in growth. The identified metabolites offer serum metabolites which could inform the nutrition and healthy development of heifers.

Integrated 16S rDNA Gene Sequencing and Untargeted Metabolomics Analyses to Investigate the Gut Microbial Composition and Plasma Metabolic Phenotype in Calves With Dampness-Heat Diarrhea

Dampness-heat diarrhea (DHD), a common syndrome in Chinese dairy farms, is mainly resulted from digestive system disorders, and accompanied with metabolic disorders in some cases. However, the underlying mechanisms in the intestinal microbiome and plasma metabolome in calves with DHD remain unclear. In order to investigate the pathogenesis of DHD in calves, multi-omics techniques including the 16S rDNA gene sequencing and metabolomics were used to analyze gut microbial compositions and plasma metabolic changes in calves. The results indicated that DHD had a significant effect on the intestinal microbial compositions in calves, which was confirmed by changes in microbial population and distribution. A total of 14 genera were changed, including Escherichia-Shigella, Bacteroides, and Fournierella, in calves with DHD (P < 0.05). Functional analysis based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) annotations indicated that 11 metabolic functions (level 2) were significantly enriched in DHD cases. The untargeted metabolomics analysis showed that 440 metabolites including bilineurin, phosphatidylcholine, and glutamate were significantly different between two groups (VIP > 1 and P < 0.05), and they were related to 67 signal pathways. Eight signal pathways including alpha-linolenic acid, linoleic acid, and glycerophospholipid metabolism were significantly enriched (P < 0.05), which may be potential biomarkers of plasma in calves with DHD. Further, 107 pairs of intestinal microbiota-plasma metabolite correlations were determined, e.g., Escherichia-Shigella was significantly associated with changes of sulfamethazine, butyrylcarnitine, and 14 other metabolites, which reflected that metabolic activity was influenced by the microbiome. These microbiota-metabolite pairs might have a relationship with DHD in calves. In conclusion, the findings revealed that DHD had effect on intestinal microbial compositions and plasma metabolome in calves, and the altered metabolic pathways and microorganisms might serve as diagnostic markers and potential therapeutic targets for DHD in calves.

Fatty acid profile characterization in colostrum, transition milk, and mature milk of primi- and multiparous cows during the first week of lactation

The specific fatty acid (FA) profile of colostrum may indicate a biological requirement for neonatal calves. The objective of this study was to characterize the FA profile and yields in colostrum, transition milk, and mature milk in primiparous (PP) and multiparous (MP) cows. Colostrum was milked from 10 PP and 10 MP Holstein cows fed the same pre- and postpartum rations. Milkings (M) 2 to 5 and 12 were respectively termed transition and mature milk. Overall, short-chain FA (C4:0 and C6:0) were 61 and 50% lower in colostrum than mature milk, respectively. A parity by milking interaction was also present, with higher C4:0 for PP cows at M2 and for MP cows at M12. Additionally, higher concentrations of C6:0 were present for PP cows at M2 through M4 and for MP cows at M12. Palmitic (C16:0) and myristic (C14:0) acids were 16% and 27% higher in colostrum than mature milk, respectively. However, total saturated FA remained relatively stable. Branched-chain FA were 13% lower in colostrum than mature milk and higher in PP than MP cows throughout the milking period. The proportion of trans-monounsaturated FA (MUFA) was 42% higher in PP cows throughout the milking period, as well as 15% lower in colostrum than mature milk. In contrast, cis-MUFA and total MUFA were not affected by milking nor parity. Linoleic acid (LA) was 13% higher in colostrum than transition and mature milks, but α-linolenic acid (ALA) did not differ. Consequently, the ratio of LA to ALA was 23% higher in colostrum than mature milk and 25% higher in MP cows. Linoleic acid was also 13% higher in MP cows, whereas ALA was 15% higher in PP cows. Conjugated linoleic acid (CLA, cis-9,trans-11) was 63% higher in PP cows, and no differences between colostrum and mature milk were detected. Overall, polyunsaturated FA (PUFA) from the n-6 and n-3 series were over 25% higher in colostrum compared with transition and mature milk. Milking by parity interactions were present for arachidonic acid (ARA), eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), docosahexaenoic acid (DHA), and total n-3 PUFA, translating to higher proportions in PP cows in M1 to M3, whereas proportions remained relatively stable throughout the milking period in MP cows. Despite increasing milk yields throughout the subsequent milkings, higher yields of EPA, ARA, DPA, and DHA were present in colostrum than in mature milk. Greater proportions and yields of n-3 and n-6 FA in colostrum may translate to specific requirements for newborn calves. Differences were also observed between PP and MP cows and may reflect different nutrient requirements and partitioning.

Effects of transport age and calf and maternal characteristics on health and performance of veal calves

The objective of this study was to investigate effects of calf transport age (14 vs. 28 d) and calf (e.g., sex and breed) and dam characteristics (e.g., parity and ease of birth) on health and performance of veal calves until slaughter age. Calves (n = 683) originated from 13 dairy farms in the Netherlands and were transported at either 14 or 28 d of age from the dairy farm to 8 Dutch veal farms. A health assessment of calves was performed on a weekly basis at the dairy farm and in wk 2, 10, 18, and 24 at the veal farm. Body weight of calves was measured on a weekly basis at the dairy farm and upon arrival at the veal farm. At the veal farm, use of antibiotics and other medicines during the rearing period (both at herd and individual level) was recorded and carcass weights were obtained from the slaughterhouse. Body weight upon arrival (Δ = 11.8 kg) and carcass weight at slaughter (Δ = 14.8 kg) were greater, and mortality risk (Δ = -3.1%) and prevalence of animals treated with medicines other than antibiotics (e.g., antiinflammatories, multivitamins, and anticoccidial drugs; Δ = -5.4%) were lower in calves transported at 28 d compared with calves transported at 14 d. Crossbreds other than Belgian Blue × Holstein Friesian received a higher number of individual treatments with antibiotics and other medicines (Δ = 14.8% and Δ = 15.1%, respectively) at the veal farm compared with Belgian Blue × Holstein Friesian calves. These findings suggest that calves transported at 28 d were more robust compared with calves transported at 14 d.

Relationship of cow and calf circulating lipidomes with colostrum lipid composition and metabolic status of the cow

Newborn calves rely on lipids in colostrum for energy and immune function. The lipid concentration in colostrum, however, is highly variable, and little is known about its composition and maternal factors that influence its composition. The first objective was to measure plasma lipid composition of multiparous cows at 35 d before calving (BC; 35 ± 3 d; ± standard deviation) and 7 d BC (7 ± 2 d), their colostrum, and serum lipid composition of calves (24 h after birth) using multiple reaction monitoring profiling, which is an exploratory and highly sensitive lipidomic analysis method that screens lipids based on chemical functionality. Second, data were analyzed to determine if there were relationships between circulating lipids in the cow, colostrum lipids, and calf serum lipids. Third, relationships between markers of metabolic status of the cows and circulating and colostrum lipids were analyzed with correlation analysis. Blood was sampled and plasma prepared from multiparous cows (n = 16) at 35 and 7 d BC. Within 3 h of parturition, colostrum was collected from cows and fed to her calf. Calves received another feeding of colostrum within 12 h after birth and a serum sample was collected from each calf 24 h after the first feeding of colostrum. The metabolic status of cows was evaluated using insulin, glucose, and nonesterified fatty acid area under the curve in response to an intravenous glucose tolerance test performed at 3 wk BC. Lipids were extracted from plasma, colostrum, and calf serum and were analyzed using multiple reaction monitoring profiling. Concentration of lipids were calculated using spiked in standards and expressed as percent of lipids identified. Data were uploaded into MetaboAnalyst 5.0 for multivariate and univariate analysis. Principal component analysis indicated that circulating lipids in the cow and calf were distinct from lipids in colostrum. Phosphatidylglycerol (PG) concentration was greater in colostrum and calf serum than in cow plasma, with 23 of the 24 PG found in colostrum also found in calf serum. In response to intravenous glucose tolerance test in late gestation, nonesterified fatty acid area under the curve was positively related to total triacylglycerols lipids in 7 d BC plasma (r = 0.63) but negatively related to total membrane lipids in colostrum (r = -0.55). Thus, the metabolic status of the dam influences circulating lipids and colostrum lipid content. Moreover, the circulating lipidome of the cow and calf are similar to one another and distinct from the colostrum lipidome, except for PG, where it appears that colostrum serves as the source for PG in the calf's circulation.

Effects of colostrum management on transfer of passive immunity and the potential role of colostral bioactive components on neonatal calf development and metabolism

Neonatal dairy and beef calves are required to ingest adequate volumes of high-quality colostrum during their first hours of life to acquire transfer of passive immunity (TPI). As such, immunoglobulin G (IgG) has largely been the focus of colostrum research over recent decades. Yet, little is known about the additional bioactive compounds in colostrum that potentially influence newborn calf development and metabolism. The purpose of this narrative review is to synthesize research regarding the effects of colostrum management practices on TPI, as well as to address the potential role of additional colostral bioactive molecules, including oligosaccharides, fatty acids, insulin, and insulin-like growth factor-I, in promoting calf development and metabolism. Due to the importance of IgG in ensuring calf immunity and health, we review past research describing the process of colostrogenesis and dam factors influencing the concentrations of IgG in an effort to maximize TPI. We also address the transfer of additional bioactive compounds in colostrum and prepartum management and dam factors that influence their concentrations. Finally, we highlight key areas of future research for the scientific community to pursue to ultimately improve the health and welfare of neonatal dairy calves.

Effect of supplementation with different fatty acid profile to the dam in early gestation and to the offspring on the finishing diet on offspring growth and hypothalamus mRNA expression in sheep

Supplementation with omega-3 and omega-9 fatty acids (FA) during late gestation regulates offspring development; however, their effect in the first third of gestation is unknown in sheep. The objective of this experiment was to evaluate the effects of the maternal supplementation with an enriched source of monounsaturated FA (MUFA) or an enriched source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) during the first third of gestation on productive performance on ewes and offspring, and hypothalamic neuropeptides on offspring. Seventy-nine post-weaning lambs, born of sheep supplemented in the first third of gestation with 1.61% Ca salts rich with MUFA or EPA+DHA (dam supplementation, DS), were distributed in a 2×2 factorial arrangement of treatments to finishing diets containing 1.48% of Ca salts of MUFA or EPA+DHA (lamb supplementation, LS). The finishing period of the offspring lasted for 56 d. During the finishing period dry matter intake (DMI, daily) and body weight (BW) were recorded. Plasma was collected for metabolites analysis. Twenty-four lambs were slaughtered, and hypothalamus was collected for mRNA expression of hormone receptors, neuropeptides, and lipid transport genes. The data were analyzed with a mixed model in SAS (9.4) using repeated measurements, when needed. There was a DS×LS interaction for BW (P = 0.10) where LS with EPA+DHA born from DS with MUFA were heavier than the other 3 treatments. Lambs born from DS with MUFA have a greater DMI (P < 0.01) than the offspring born from DS with EPA+DHA. Lambs born from MUFA supplemented dams had a greater (P ≤ 0.05) hypothalamus mRNA expression for cocaine and amphetamine regulated transcript, growth hormone receptor, metastasis suppressor 1, leptin receptor, pro-opiomelanocortin, and Neuropeptide Y. These results indicate that growth depends not on the type of FA during the finishing phase but the interaction of different sources of FA ad different stages. Also, supplementation with FA during early pregnancy changes productive performance and neuropeptides' mRNA expression of lambs independently of the finishing diet.

The effect of supplemental bioactive fatty acids on growth performance and immune function of milk-fed Holstein dairy calves during heat stress

The present study aimed to evaluate the effects of different supplemental fat sources (soyabean oil (SBO) as a source of n-6 fatty acid (FA) and fish oil (FO) as a source of n-3 FA) in the starter feed of milk-fed dairy calves during the hot season. Forty Holstein calves (3 d of age; 39·67 kg of body weight; ten calves per group) were randomly assigned to the experimental treatments as follows: (1) starter feed supplemented with no fat source (CON), (2) starter feed supplemented with 3 % SBO (DM basis), (3) starter feed supplemented with 3 % FO (DM basis) and (4) starter feed supplemented with an equal mixture of SBO and FO (1·5 % each, DM basis). The milk feeding schedule was constant for treatments and all calves were weaned on day 65 of age. Results show that calves had greater starter intake, average daily gain and body length when fed SBO compared with the other treatments. However, feed efficiency was increased and inflammatory indicators (TNF-α, serum amyloid A and haptoglobin) concentrations were reduced in the calves fed FO compared with the other treatments. In summary, it was revealed that SBO rich in n-6 FA improved starter intake and growth performance, while FO rich in n-3 FA could improve the immune function of calves. Due to the current experimental condition, an equal mixture of SBO and FO (1·5 % each, DM basis) can be recommended to have an optimum growth performance and immune function while the calves are reared under the heat conditions.

Effects of milk feeding strategies on short- and long-term productivity of Holstein heifers

Research investigating the effects of feeding raw or pasteurized nonsaleable milk (NSM) on heifers' performance beyond the period of supplementation is limited. This study aimed to examine the effects of type of milk [NSM or milk replacer (MR)] and pasteurization of NSM on preweaning and first-lactation performance of heifers born with low (<36.3 kg) or normal birth weight (≥36.3 kg). Holstein heifers (n = 154) were sequentially assigned to 1 of 3 treatments: MR, pasteurized NSM, or raw NSM. Heifers assigned to raw NSM were fed raw colostrum, whereas heifers assigned to MR and pasteurized NSM were fed pasteurized colostrum. The low birth weight heifers were fed 1.4 L at each feeding until they reached 36.3 kg body weight, whereas normal birth weight heifers were fed 1.9 L at each feeding. A grain mix starter was offered throughout the study. Heifers were weaned ≥42 d old if consuming at least 0.9 kg/d of starter for 3 consecutive days. Data were analyzed with the MIXED procedure of SAS (SAS Institute Inc., Cary, NC), and the basic model included milk treatments, birth weight group, and treatment × birth weight group. The low birth weight heifers fed raw colostrum and NSM versus pasteurized colostrum and NSM had lower serum protein concentrations. Heifers fed MR versus NSM had or tended to have greater concentrations of hematocrit, red blood cells, and eosinophils but lesser concentrations of platelets, although some of those responses were temporary. Pasteurization tended to increase blood lymphocyte concentrations. Heifers with normal birth weight had greater concentrations of blood neutrophils, lymphocytes, and monocytes, compared with low birth weight heifers. For the first 42 d of life, low birth weight heifers fed pasteurized versus raw NSM had greater weight gain, grain intake, and feed efficiency and were weaned earlier (hazard ratio for weaning by 56 d: 2.90). These pasteurization effects for low birth weight heifers tended to be sustained through 24 wk of age, indicated by greater weight gain and hip height growth. In their first lactation, low birth weight heifers produced less mature-equivalent (MEq) protein and tended to produce less MEq milk and fat than normal birth weight heifers. However, the negative effects of low birth weight on MEq milk and fat yield was only evident in heifers fed raw NSM, whereas the performance of low birth weight heifers was similar to that of normal birth weight when fed MR or pasteurized NSM. These findings confirm that calf management practices influence future performance; in this case, failing to pasteurize milk and colostrum for low birth weight heifers had effects that remained apparent for more than 2 years.

The influence of dietary supplementation with the leucine metabolite β-hydroxy-β-methylbutyrate (HMB) on the chemotaxis, phagocytosis and respiratory burst of peripheral blood granulocytes and monocytes in calves

Background

A healthy immune system plays a particularly important role in newborns, including in calves that are far more susceptible to infections (viral, bacterial and other) than adult individuals. Therefore, the present study aimed to evaluate the influence of HMB on the chemotactic activity (MIGRATEST® kit), phagocytic activity (PHAGOTEST® kit) and oxidative burst (BURSTTEST® kit) of monocytes and granulocytes in the peripheral blood of calves by flow cytometry.

Results

An analysis of granulocyte and monocyte chemotactic activity and phagocytic activity revealed significantly higher levels of phagocytic activity in calves administered HMB than in the control group, expressed in terms of the percentage of phagocytising cells and mean fluorescence intensity (MFI). HMB also had a positive effect on the oxidative metabolism of monocytes and granulocytes stimulated with PMA (4-phorbol-12-β-myristate-13-acetate) and Escherichia coli bacteria, expressed as MFI values and the percentage of oxidative metabolism.

Conclusion

HMB stimulates non-specific cell-mediated immunity, which is a very important consideration in newborn calves that are exposed to adverse environmental factors in the first weeks of their life. The supplementation of animal diets with HMB for both preventive and therapeutic purposes can also reduce the use of antibiotics in animal production.

Effects of linseed oil and rumen undegradable protein:rumen degradable protein ratio on performance of Holstein dairy calves

The present study evaluated the interaction effects of n-3 fatty acids (from linseed oil (LSO), 0 v. 2·5, % DM basis) with rumen undegradable:degradable protein (RUP:RDP) ratios (low ratio (LR) 27:73; high ratio (HR) 38:62 based on crude protein %) in dairy calves' starter diet. Forty-eight 3-d-old female Holstein dairy calves (41·5 kg of body weight (BW)) were allocated in a 2 × 2 factorial arrangements in the following treatments (n 12 calves/each): (1) no supplementation of LSO with LR (NLSO-LR); (2) no supplementation of LSO with HR (NLSO-HR); (3) supplementation of LSO with LR (LSO-LR) and (4) supplementation of LSO with HR (LSO-HR). The calves were weaned on day 53 of the experiment and remained in the study until day 73. Intake was not affected by LSO and RUP:RDP ratio. However, average daily gain (ADG) was improved with LSO supplementation. Feeding the HR diet increased ADG compared with the LR diet during the entire period. Final BW was greater in calves fed on the LSO than those fed the NLSO diet. Microbial protein production did not differ among treatments. Calves fed on LSO diets had greater feed efficiency than those which were not fed on LSO diets. The calves supplemented with LSO had greater wither and hip heights compared with the unsupplemented calves. The glucose, cholesterol, HDL and insulin concentrations increased in calves supplemented with LSO. In conclusion, the HR diet improved calves' performance post-weaning; however, LSO could enhance growth performance of dairy calves during the pre-weaning period.

Effects of n-3 fatty acids on growth, antioxidant status, and immunity of preweaned dairy calves

This study aimed to estimate the influences of flax oil and a mixture of ethyl esters of fatty acids from flax oil added to a milk replacer (MR) formulation on the biochemical, immunological, and antioxidant status of blood, production parameters, and health of calves. Twenty-seven Holstein-Frisian calves were assigned to 3 groups: the control group without fat added to the diet (CON, n = 9), a group receiving ethyl esters of flax oil (10 g/d) with lyophilized apples (25 g; MRE), or a group receiving flax oil (10 g/d) with lyophilized apples (25 g; MRL). The study was conducted from d 14 to d 42 of life. Intake of MR and feed were recorded daily, and fecal scores, rectal temperature, and body weight were recorded weekly. Laboratory blood tests were conducted every 7 d from d 14 to 42. Supplementation with the formulation containing ethyl esters of flax oil (MRE) positively affected health, average daily weight gain, growth rate, and feed efficiency. Intake of the starter feed was lower in the calves receiving the formulation with flax oil (MRL). The MRE formulations lowered the concentrations of triglycerides, total cholesterol, and LDL fraction in blood serum and decreased the total antioxidant capacity (TAS) and levels of glutathione peroxidase (GPx). The MRL formulation increased TAS and GPx levels in blood serum. The MRE treatment limited the circulating levels of tumor necrosis factor. The MRE and MRL preparations lowered the concentration of SFA (C16:0, C18:0, C18:1) in blood serum, and MRE significantly increased levels of α-linolenic acid. The MRE and MRL preparations beneficially affected production and physiological parameters. Our data support the idea that supplementation with n-3 fatty acids improves calf growth and metabolic and oxidative functions in young calves.

Effects of fatty acids and calf starter form on intake, growth, digestion, and selected blood metabolites in male calves from 0 to 4 months of age

The objective of this research was to determine if form of calf starter (CS) and addition of a fatty acid blend (FA) influenced intake, growth, digestion, and indices of immune status and stress in calves from 0 to 4 mo of age. Male Holstein calves [n = 48; 41.9 kg of body weight (BW), standard error = 0.7; 2 to 3 d of age] were assigned to receive reconstituted whole milk powder [0.66 kg of dry matter (DM)/d to 39 d, then 0.33 kg of DM/d to weaning at 42 d] without or with added FA. Calf starters were textured (pellet, whole oats, whole corn) or pelleted and were offered for ad libitum consumption from 0 to 56 d, then blended with 5% chopped grass hay and fed from d 57 to 112. Starters contained 20% crude protein (CP) and 38 to 40% starch in the DM. From d 0 to 56, calves were housed individually. From d 57 to 112, calves were grouped into pens by treatment (n = 4/pen). Form of CS during the initial 56 d had no effect on intake or growth, though days with fluid feces (fecal score ≥2.5) were greater when calves were fed textured CS. Feeding FA during the initial 56-d increased average daily BW gain, gain-to-feed ratio, and change in hip width, and reduced the number of days calves were treated with antibiotics. During d 57 to 112, CS form had no effects on any performance measure. Adding FA to CS increased average daily BW gain and hip width change, and tended to improve efficiency of BW gain. Total-tract digestibility was estimated at 4, 6, and 8 wk with 5 calves per treatment, and at 10, 13, and 16 wk of age using pen (n = 3 per treatment) as the experimental unit. Feeding FA increased or tended to increase total-tract digestion of DM, organic matter, starch, neutral detergent fiber (NDF), acid detergent fiber (ADF), CP, and fat at one or more measurement periods. Calves fed a textured CS increased or tended to increase digestion of DM, organic matter, starch, sugar, NDF, ADF, and CP during wk 6 and 8. However, during the second 56-d phase, feeding textured CS reduced or tended to reduce digestion of DM, organic matter, starch, NDF, ADF, and fat during wk 13 and 16. Inclusion of FA in milk increased serum bactericidal activity before weaning. Serum haptoglobin concentration increased 3 d postweaning when calves were fed textured CS. Feeding FA improved animal health, digestion, and performance. Form of CS had few effects on animal performance.

Level and source of fat in the diet of gestating beef cows: II. Effects on the postpartum performance of the dam and the progeny

A study was conducted to evaluate the effects of level and source of fat in the diet of gestating beef cows on the postpartum performance of the dam and the progeny. Each year, 75 mature pregnant (183±4.8 d until calving) Angus cows with similar BW (663±21.5 kg) and BCS (2.6±0.12; 1 to 5 scale) were randomly assigned to one of 15 outdoor pens. Each pen was assigned to one of three iso-caloric and iso-nitrogenous treatments: a low-fat diet (LF; 1.4±0.12% EE), and two high-fat diets (HF; 3.3±0.20% EE) including a canola seed (CAN) or a flaxseed (FLX) based pelleted feed. Diets were formulated to meet the requirements of pregnant beef cows and fed until calving. Data were analyzed as a randomized complete block design with contrasts for the effects of level (LF vs. HF) and source (CAN vs. FLX) of fat. No differences (P≥0.21) were found for BW or calving to weaning ADG of cows. The average BCS during the first 42 d of lactation was greater (P<0.01) for LF compared to HF (2.63 vs. 2.51) with no difference (P=0.35) for CAN vs. FLX cows. Subcutaneous fat thickness over the ribs was greater (P≤0.01) for LF compared to that of HF cows at calving (5.7 vs. 4.3 mm) and at weaning (4.3 vs. 3.7 mm) with no difference (P≥0.11) for CAN vs. FLX cows. Over the first 42 d of lactation, no difference (P≥0.23) was observed for 12-h milk yield. Milk protein concentration was greater (P=0.03) for CAN compared to FLX (3.11 vs. 3.01%) cows while no difference (P≥0.28) was observed for any other milk component. Milk fat from FLX cows had greater (P < 0.01) CLA and CLnA concentrations than that of CAN cows during the first 42 d of lactation. Pregnancy rate of HF cows tended (P=0.07) to be greater than that of LF cows with no difference (P=0.77) for CAN vs. FLX cows. Calves from HF cows were heavier (P≤0.01) at birth (42.9 vs. 40.2 kg) than those from LF cows. From calving to weaning, ADG of calves born to CAN cows was greater (P=0.03) that that of calves born to FLX cows (1.19 vs. 1.13 kg/d) with no difference (P=0.18) for calves born to LF vs. HF cows. At slaughter, progeny of HF cows had greater (P≤0.03) shrunk BW (605 vs. 579 kg) and HCW (355 vs. 339 kg) compared to those from LF cows with no difference (P≥0.16) for progeny of CAN vs. FLX cows. These results show that feeding a HF diet over gestation results in heavier calves at birth and at slaughter, and superior calf gains from birth to slaughter as well as heavier carcasses, possibly due to a developmental programming effect.

Effect of supplementation with n-3 polyunsaturated fatty acids and/or β-glucans on performance, feeding behaviour and immune status of Holstein Friesian bull calves during the pre- and post-weaning periods

Background

Previous research in both calves and other species has suggested n-3 polyunsaturated fatty acids (PUFA) and β-glucans may have positive effects on immune function. This experiment measured performance, behaviour, metabolite and immunological responses to pre-weaning supplementation of dairy bull calves with n-3 PUFA in the form of fish oil and β-glucans derived from seaweed extract. 44 Holstein Friesian bull calves, aged 13.7 ± 2.5 d and weighing 48.0 ± 5.8 kg were artificially reared using an electronic feeding system. Each calf was offered 5 L (120 g/L) per day of milk replacer (MR) and assigned to one of four treatments included in the MR, (1) Control (CON); (2) 40 g n-3 PUFA per day (FO); (3) 1 g β-glucans per day (GL) and (4) 40 g n-3 PUFA per day & 1 g/d β-glucans (FOGL) in a 2 × 2 factorial design. Milk replacer and concentrate was offered from d 0–62 (pre-weaning), while concentrate provision continued for a further 31 d post-weaning period. Individual daily feed intake and feeding behaviour was recorded throughout, while bodyweight and blood analyte data were collected at regular intervals.

Results

Overall mean concentrate DMI from d 0–93 was 1.39, 1.27, 1.00 and 0.72 kg/d for CON, FO, GL and FOGL calves, respectively (SEM = 0.037; P < 0.0001). Calves supplemented with GL were significantly lighter (P < 0.0001) at both weaning (d 62) and turnout to pasture (d 93) than un-supplemented calves, with a similar effect (P < 0.0001) evident for calves receiving FO compared to un-supplemented contemporaries. Supplementation with GL reduced the number of unrewarded visits where milk was not consumed (P < 0.0001) while supplementation with FO increased mean drinking speed (P < 0.0001). Supplementation with GL resulted in greater concentrations of haptoglobin (P = 0.034), greater serum osmolality (P = 0.021) and lower lymphocyte levels (P = 0.027). In addition, cells from GL supplemented calves exhibited a lower response than un-supplemented contemporaries to both Phytohaemagglutinin A stimulated IFN-γ (P = 0.019) and Concanavalin A stimulated IFN-γ (P = 0.012) following in vitro challenges.

Conclusions

Pre-weaning supplementation of bull calves with either n-3 PUFA or β-glucan resulted in reduced voluntary feed intake of concentrate and consequently poorer pre-weaning calf performance. There was no evidence for any beneficial effect of either supplementation strategy on calves’ immune responses.

Evaluating Potential Biomarkers of Health and Performance in Veal Calves

Veal calves undergo many challenges in the early stages of their life. Such challenges, including mixing procedures and transportation of calves to the veal farm, may have a negative influence on growth rate, feed intake, metabolism, immunity and disease susceptibility of calves. As a consequence, many hematological, physiological, metabolic and immunological parameters of stressed calves might be altered on arrival at the veal farm. Some of these response variables might be useful as biomarkers of performance of calves at the veal farm as they might provide information about an ongoing disease process, or may predict future diseases. Biomarkers might be helpful to group and manage calves in different risk categories after arrival. By adopting treatment decisions and protocols on a risk-group or individual basis, it would be possible to improve animal health and reduce both disease incidence and antibiotic use. Moreover, the use of biomarkers might be an economically feasible approach as some of them do not need invasive techniques and others can be measured in blood already taken during routine checks. Previous literature mainly assessed the physiological responses of calves to transportation. However, information on the link between on-farm arrival data and future health and performance of veal calves is limited. This review, therefore, examined a wide range of papers and aimed to identify potential biomarkers of future health and performance.

Supplementation of essential fatty acids to Holstein calves during late uterine life and first month of life alters hepatic fatty acid profile and gene expression

Linoleic acid is an essential dietary fatty acid (FA). However, how the supplementation of linoleic acid during uterine and early life may modify the FA profile and transcriptome regulation of the liver, and performance of preweaned dairy calves is unknown. Our objective was to evaluate the effect of supplementation of essential FA to Holstein calves during late uterine and early life on their hepatic FA profile and global gene expression at 30 d of age. During the last 8 wk of pregnancy, Holstein cattle (n=96) were fed either no fat supplement (control), a saturated FA supplement enriched with C18:0, or an unsaturated FA supplement enriched with linoleic acid. Male calves (n=40) born from these dams were fed a milk replacer (MR) with either low (LLA) or high linoleic acid (HLA) concentration as the sole feedstuff during the first 30 d. Liver biopsy was performed at 30 d of age, and microarray analysis was performed on 18 liver samples. Total concentration of FA in liver were greater in calves fed LLA compared with those fed HLA MR (8.2 vs. 7.1%), but plasma concentrations of total FA did not differ due to MR diets. The FA profiles of plasma and liver of calves were affected differently by the prepartum diets. Specifically, the FA profile in liver was affected moderately by the feeding of fat prepartum, but the profiles did not differ due to the type of FA fed prepartum. The type of MR fed during the first 30 d of life had major effects on both plasma and liver FA profiles, resembling the type of fat fed. Plasma and liver of calves fed LLA MR had greater percentage of medium-chain FA (C12:0 and C14:0), whereas plasma and liver from calves fed HLA MR had greater percentages of linoleic and α-linolenic acids. Dams fed fat or a specific type of FA modified the expression of some genes in liver of calves, particularly those genes involved in biological functions and pathways related to upregulation of lipid metabolism and downregulation of inflammatory responses. Feeding HLA instead of LLA MR modified the expression of hepatic genes, including genes predicted to decrease infections and to increase lipid utilization and protein synthesis. Research evaluating the effect of FA supplementation during uterine and neonatal life on the future productivity of the neonate is warranted.