Oral administration of Pinus koraiensis cone essential oil reduces rumen methane emission by altering the rumen microbial composition and functions in Korean native goat (Capra hircus coreanae)

This study aimed to investigate Pinus koraiensis cone essential oil (PEO) as a methane (CH₄) inhibitor and determine its impact on the taxonomic and functional characteristics of the rumen microbiota in goats. A total of 10 growing Korean native goats (Capra hircus coreanae, 29.9 ± 1.58 kg, male) were assigned to different dietary treatments: control (CON; basal diet without additive) and PEO (basal diet +1 g/d of PEO) by a 2 × 2 crossover design. Methane measurements were conducted every 4 consecutive days for 17-20 days using a laser CH₄ detector. Samples of rumen fluid and feces were collected during each experimental period to evaluate the biological effects and dry matter (DM) digestibility after PEO oral administration. The rumen microbiota was analyzed via 16S rRNA gene amplicon sequencing. The PEO oral administration resulted in reduced CH₄ emission (eructation CH₄/body weight^0.75, p = 0.079) without affecting DM intake; however, it lowered the total volatile fatty acids (p = 0.041), molar proportion of propionate (p = 0.075), and ammonia nitrogen (p = 0.087) in the rumen. Blood metabolites (i.e., albumin, alanine transaminase/serum glutamic pyruvate transaminase, creatinine, and triglyceride) were significantly affected (p < 0.05) by PEO oral administration. The absolute fungal abundance (p = 0.009) was reduced by PEO oral administration, whereas ciliate protozoa, total bacteria, and methanogen abundance were not affected. The composition of rumen prokaryotic microbiota was altered by PEO oral administration with lower evenness (p = 0.054) observed for the PEO group than the CON group. Moreover, PICRUSt2 analysis revealed that the metabolic pathways of prokaryotic bacteria, such as pyruvate metabolism, were enriched in the PEO group. We also identified the Rikenellaceae RC9 gut group as the taxa potentially contributing to the enriched KEGG modules for histidine biosynthesis and pyruvate oxidation in the rumen of the PEO group using the FishTaco analysis. The entire co-occurrence networks showed that more nodes and edges were detected in the PEO group. Overall, these findings provide an understanding of how PEO oral administration affects CH₄ emission and rumen prokaryotic microbiota composition and function. This study may help develop potential manipulation strategies to find new essential oils to mitigate enteric CH₄ emissions from ruminants.

An Evaluation of Nutritional and Therapeutic Factors Affecting Pre-Weaned Calf Health and Welfare, and Direct-Fed Microbials as a Potential Alternative for Promoting Performance—A Review

The priority for calf rearing has been to maintain good health and welfare in order to promote and sustain future production. However, there have been numerous reports of undesirable levels of morbidity and mortality amongst pre-weaned calves. This may be mitigated or exacerbated by nutritional management practices. Some areas of concern include colostrum feeding, utilization of waste milk, and restrictive milk feeding regimes. Antibiotics may be prescribed at lethal or sub-inhibitory doses to treat or prevent disease. However, extensive antibiotic use may disrupt the gastrointestinal microbiota and aid in expanding the antibiotic resistant gene pool. In an attempt to reduce the use of antibiotics, there is a demand to find alternative performance enhancers. Direct-fed microbials, also known as probiotics, may comply with this role. A DFM consists of live microorganisms that are biologically active and able to confer health benefits onto the host. Lactic acid bacteria have been the most frequently investigated; however, this field of research has expanded to include spore-forming bacteria and live yeast preparations. This review aims to provide a comprehensive evaluation of the nutritional management strategies that may increase a calf’s susceptibility to morbidity and mortality, the efficacy and sustainability of antibiotics as a tool for managing calf health and welfare, and the potential for DFMs as a supportive strategy for promoting calf wellbeing.

Milk Replacer Ingredients: What and Why?

CMR's should be composed primarily of milk proteins, lactose as the sole carbohydrate source, lipids composed of edible grade tallow or lard with consideration for medium-chain fatty acids derived from coconut oil that mimic those in milk fat and adequate vitamin and mineral nutrition. Spray-dried bovine plasma provides antibodies shown to reduce diarrhea and calf mortality and to effectively replace a significant portion of milk protein in the diet. Whole milk pasteurization must be intensely monitored to ensure it is consistently wholesome. Milk is deficient in vitamins and trace minerals.

Meta-analysis of effects of age on intestinal digestibility of liquid feeds in young calves

A meta-analysis was conducted to determine the effect of age on digestibility of liquid feeds fed to preweaned Holstein calves. Calves were 4 to 76 d of age and fed whole milk or milk replacer containing all-milk protein. Least squares means of apparent total-tract N, DM, and fat digestibilities (n = 84, 51, and 24, respectively) from 12 publications were used. Broken line regression and mixed model ANOVA were used to determine ages at which digestion of nutrients no longer increased with age, indicating maturation of digestive capacity. Digestibility of DM, N, and fat reached maximum digestibilities of 94.1, 92.7, and 97.5% at 29, 29, and 32 d of age, respectively. These data indicate age-related changes in digestion of liquid feeds in preweaned Holstein calves and allow correction of apparent total-tract digestibility estimates in nutrient supply models. Digestibility of liquid nutrients in calves fed whole milk or all milk containing milk replacers reached maximal capacity at approximately 30 d of age.

Effects of milk replacer feeding rate and fat content on Jersey calf nutrient digestion and performance to 4 months of age

This study evaluated effects of milk replacer (MR) feeding rate and fat concentration in MR on total-tract digestion (TTD) and growth performance in Jersey calves. Jersey heifer calves (n = 100, 2 blocks of 50; initially 30 ± 3.0 kg of body weight; 4-11 d of age) were randomly assigned to 1 of 4 treatments in a 2 × 2 factorial arrangement of MR feeding rate [454 g for 42 d, and 227 g for 7 d (MOD); or 454 g for 7 d, 681 g for 35 d, and 341 g for 7 d (HI), as-fed basis] and MR fat content (17 or 24% fat as-fed basis). Milk replacers (24% crude protein as-fed basis) were reconstituted to 14% solids and fed in 2 equal feedings for 42 d, and then mornings only for 7 d. Textured calf starter (21% crude protein, 40% starch, dry matter basis) and water were offered for ad libitum consumption. From d 57 to 112, calf starter was mixed with 5% chopped grass hay. Calves were housed individually to d 56 and housed in groups (4-5 calves/pen) from d 57 to 112. Estimates of TTD were measured in 5 calves/treatment (block 1) at wk 3 of the study using acid-insoluble ash as an indigestible marker. From 0 to 56 d, calf starter intake (CSI) was greater for MOD vs. HI and 17 versus 24% fat; average daily gain was greater for HI versus MOD; and hip width change was greater for 17 versus 24% fat. Estimates of organic matter TTD were greater for HI versus MOD, but neutral detergent fiber TTD was greater for MOD versus HI and for 17 versus 24% fat. From 57 to 112 d, hip height change was greater for MOD versus HI, and hip width change was greater for 17 versus 24% fat. In this study, feeding Jersey calves more MR improved preweaning average daily gain, but had a negative effect on CSI and likely rumen development, as neutral detergent fiber TTD was reduced at 3 wk and frame growth was reduced from d 57 to 112. This resulted in similar final calf body weights between MR feeding rates at the end of the study. No benefits were observed for feeding more fat in MR as CSI or for NDF digestibility, and frame growth was reduced.

The effect of milk quantity and feeding frequency on calf growth and behaviour

Context Calves left with their dam to suckle will consume ~7–12 L/day; however, the amount of milk provided to dairy young calves removed from their dams may often be as low as 4 L/day, or 10% of their bodyweight. Aims This study compared once and twice daily feeding, as well as feeding levels of 10 and 20% of bodyweight and studied the effect on behaviour and metabolic indicators indicative of hunger. Methods Forty-six male dairy calves were allocated to one of three treatments from 3 to 8 days of age: (i) 10% of bodyweight offered daily as one meal (1 × 10%, n = 16); (ii) 10% of bodyweight offered daily over two meals (2 × 5%, n = 15); or (iii) 20% of bodyweight offered over two meals (2 × 10%, n = 15). Behaviour during and after feeding was observed by video, and blood samples taken on selected days were analysed for glucose, nonesterified fatty acids (NEFA), cortisol and packed-cell volume. Key results Milk intake on Days 3 and 4 was lower in those calves fed once daily compared with calves fed twice daily. Calves fed at 20% bodyweight had higher milk intake compared with calves fed at 10% bodyweight on all days other than Day 3 and growth was higher in those calves. Non-nutritive sucking was mainly associated with feeding times and it was highest in calves fed 10% bodyweight over two meals, with a suckling pattern that suggested that feeding at 10% bodyweight satisfied feeding motivation less than feeding at 20% bodyweight. Play behaviour was reduced in calves fed once daily, suggesting hunger and reduced welfare. There were significant effects on physiological indicators of metabolic state. NEFA concentrations were significantly higher in calves fed once daily and calves fed 10% of bodyweight at certain time points, indicating a lower energy balance. Conclusions Feeding twice daily offers benefits to calves up to Day 4 of life whereas feeding 20% of bodyweight was beneficial after Day 4 to increase satisfaction of feeding motivation and nutrition for growth. Although metabolic variables were within normal physiological range for all treatments, the effects on feed intake, growth and non-nutrient sucking suggest marked effects on hunger when calves are fed the lower milk allowance. Implications The fairly common practice of feeding dairy calves 10% of bodyweight, in one or two daily meals may leave calves hungry, and an increase in milk allowance should be considered.

Effects of colostrum and milk replacer feeding rates on intake, growth, and digestibility in calves

Newborn Holstein male calves (n = 50) born on a single dairy farm were assigned randomly at birth to receive 3 feedings of 1.8 L of pooled maternal colostrum (MC) at 1, 6, and 12 h of age or 1 feeding of 500 g of a colostrum replacer reconstituted to 1.8 L at 1 h of age, followed by 2 feedings of 227 g of a commercial milk replacer (MR) reconstituted to 1.8 L at 6 and 12 h of age (CR). All feedings were administered by esophageal feeder. At 2 to 3 d of age, calves were transported to the experimental facility and assigned within colostrum group to receive 0.66 kg/d dry matter (DM) of MR to 39 d, and then 0.33 kg/d to 42 d (MRM) or 0.77 kg/d of MR DM to d 13, 1.03 kg/d for 22 d, and 0.51 kg/d for 7 d (MRH). The MR contained 25.8% crude protein and 17.6% crude fat (DM basis) and was based on whey proteins and lard as the primary fat source. Calf starter (21.7% crude protein, 15.7% neutral detergent fiber, 37.4% starch, DM basis) and water were available for ad libitum consumption throughout the 56-d study. Serum IgG and total protein were measured at 2 to 3 d of age. Intakes of MR and calf starter were monitored daily. Calf health and fecal scores were also monitored daily. Body weight was measured weekly, and hip width and body condition score were monitored every 2 wk. Digestion of DM, organic matter, crude protein, and ether extract were determined at 1 and 3 wk from 5 calves randomly selected within treatment and using chromic oxide as a digestibility marker added to the MR. Calves fed CR had lower serum IgG and total protein than calves fed MC. Also, calves fed CR grew more slowly, consumed less calf starter, and were less efficient to 56 d than calves fed MC. The number of days calves were treated with veterinary medications was higher when calves were fed CR. Calves fed MC-MRH gained more BW than other calves from 3 to 8 wk of age. Calves fed CR-MRH consumed less calf starter than other calves during wk 7 and 8. Digestion of nutrients at 1 and 3 wk of the study was unaffected by type of colostrum or level of MR fed and did not change from 1 to 3 wk. Over the first 2 mo of life, the calves fed MRH consumed less calf starter than calves fed MRM, but average daily gain or hip width change did not differ. One feeding of CR followed by 2 feedings of MR in the first 24 h likely reduced absorption of IgG from CR and contributed to differences in health and growth. Differences in animal performance observed in this study were unrelated to MR digestibility.

Evaluation of a multispecies probiotic as a supportive treatment for diarrhea in dairy calves: A randomized clinical trial

The objectives of this randomized clinical trial were to determine whether the utilization of a multispecies probiotic bolus (MSP) in dairy calves with diarrhea led to a rapid resolution of diarrhea and improved average daily gain (ADG). Calves, from a convenience sample of dairy farms with diarrhea challenges, having fecal scores of ≥2 were randomly assigned to receive MSP or a placebo (PLB). The MSP bolus contained Pediococcus acidilactici, Enterococcus faecium, Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium bifidum, peptide extract, an enzyme blend, killed yeast extract, dried whey, and natural flavors (Revive, Partnar Animal Health, Ilderton, ON, Canada). The enrolled calves were fecal scored daily for 7 consecutive days and resolution of diarrhea was defined as having 2 consecutive days with a fecal score ≤1. Calves were also weighed at enrollment, 7, and 14 d following enrollment and ADG was calculated. A Cox proportional hazards model was built to investigate time to resolution of an abnormal fecal score. Two mixed linear regression models were created to evaluate the effect of treatment group on ADG in the first and second weeks following enrollment. A total of 148 calves were enrolled in the experiment and no differences were observed between the groups with respect to the age or weight at enrollment. The mean time to resolution of abnormal fecal score was 5.1 and 5.9 d in the MSP and PLB groups, respectively. In the Cox proportional hazards model, the calves in the MSP group had faster resolution of diarrhea when compared with the PLB group; however, an interaction between time from enrollment of the first calf and treatment group was present. No differences were found between the 2 groups with respect to ADG. This study demonstrates a multispecies probiotic and yeast bolus administered to calves at the onset of diarrhea reduced the duration of diarrhea; however, the clinical and economic relevance of this reduction requires further exploration.

Symposium review: Re-evaluation of National Research Council energy estimates in calf starters

Provision of nutrients in appropriate amounts to meet nutrient requirements for growth, production, and reproduction is the basis for modern animal nutrition. Ration formulation systems predict nutrient requirements based on numerous inputs and then predict nutrient supply based on predicted intake and nutrient content of feeds. Energy systems are used to predict energy supply based on gross caloric content of feeds followed by adjustments for digestion and metabolism of ingested energy. Many models of energy supply use static coefficients of digestibility based on nutrient composition of feed. Other models partition digestion dynamically between ruminal and postruminal digestion but use static estimates of intestinal digestibility to predict energy supplied to the animal. In young calves, both ruminal fermentation and intestinal digestion are underdeveloped; therefore, existing models of energy supply might overestimate the energy available before complete gastrointestinal maturation. In a series of experiments, we reported that total-tract digestion of nutrients changes with advancing age and nutrient intake. Total-tract digestion was measured in calves from 3 to 16 wk of age when fed different amounts and types of milk replacers. Calves were also fed different types of calf starter for ad libitum consumption. Total-tract digestibility of protein, fat, neutral detergent fiber, and nonfiber carbohydrate (NFC) was used to calculate the metabolizable energy (ME) in starter. We used nonlinear regression to estimate the contribution of protein and fat from starter and milk replacer before weaning. Early in life, calculated ME of starter was low and increased with increasing intake of NFC. Cumulative intake of NFC was more highly correlated with changing ME values than other indices, including age, intake of milk replacer, or intake of other nutrients in starter. When calves consumed at least of 15 kg of NFC, ME calculated from digestibility measurements was similar to the ME calculated using National Research Council equations and indicated maturation of gastrointestinal digestion. Our data suggest that intake of NFC is critical to gastrointestinal maturation and the calf's ability to extract energy from calf starter.

Varying dietary protein and fat elicits differential transcriptomic expression within stress response pathways in preweaned Holstein heifers

Increases in milk replacer dietary energy subsequently increase growth and weight in preweaned dairy heifers. However, the underlying effects of dietary component increases on key functional pathways have yet to be fully investigated. Elucidating these relationships may provide insights into the mechanisms through which protein and fat are partitioned for tissue growth and metabolism. We hypothesized that genes within key growth and metabolic pathways would be differentially expressed between calves fed a protein- and fat-restricted diet and calves fed a protein- and fat-enhanced diet. The objectives of this study were to (1) identify genes differentially expressed between dietary restricted calves and enhanced calves and (2) determine the key regulatory pathways influenced by these genes. Preweaned Holstein heifers (n = 12; 6 ± 0.02 d of age) were randomly assigned to 1 of 2 milk replacer diets: enhanced (28.9% crude protein, 26.2% fat; n = 6) or restricted (20.9% crude protein, 19.8% fat; n = 6). Growth measures included average daily gain and gain-to-feed ratio. After 56 d, calves were killed for tissue collection. Samples from longissimus dorsi, adipose, and liver tissues were collected and RNA was isolated for RNA sequencing analysis. The MIXED procedure of SAS (SAS Institute Inc., Cary, NC) was used to evaluate relationships of growth with dietary energy. Fixed effects included date of collection and time (day). Random effects included sire and birth weight. The RNA sequencing analysis was performed using CLC Genomics Workbench (Qiagen, Germantown, MD), and the Robinson and Smith exact test was used to identify differentially expressed genes between diets. The Protein Analysis Through Evolutionary Relationships (PANTHER) database was then used to identify functional categories of differentially expressed genes. Enhanced calves had increased growth rates and feed efficiency compared with restricted calves (average daily gain = 0.76 and 0.22, respectively; gain-to-feed ratio = 0.10 and 0.06, respectively). There were 238 differentially expressed genes in adipose, 227 in longissimus dorsi, and 40 in liver. We identified 10 genes concordant among tissues. As expected, functional analyses suggested that the majority of genes were associated with metabolic or cellular processes, predominantly cell communication and cell cycle. Overall, it appears that varying levels of dietary protein and fat influence calf growth and development through metabolic processes, including oxidative phosphorylation and glyceroneogenesis. However, protein- and fat-restricted calves appeared to experience metabolic stress at a cellular level, as evidenced by an upregulation in stress response pathways, including genes in the p53 pathway. Calves could be fed at a higher level of protein and fat to decrease the prevalence of metabolic stress at the cellular level, but evidence indicating the presence of inflammatory stress and adipose fibrosis in enhanced calves prompts further investigation of the effects of milk replacer component levels.

A 100-Year Review: Calf nutrition and management

The first calf paper, published in the May 1919 issue of the Journal of Dairy Science (JDS), described factors affecting birth body weight of different breeds of calves. Other studies were done on nonmilk ingredients, growth charts were developed, and early weaning was followed to conserve milk fed to calves. Calf papers did not report use of statistics to control or record variation or to determine whether treatment means were different. Many experiments were more observational than comparative. Typically fewer than 5 calves, and sometimes 1 or 2 calves, were used per treatment. During the next 20 yr, calf studies increased and included colostrum feeding, milk and milk replacer feeding, minerals and vitamins, and fats and oils. Many concepts fundamental to current knowledge and understanding of digestion, rumen development, and milk replacer formulation were developed during this period. In addition, the concept of using antibiotic growth promoters in dairy calf diets was first evaluated and developed during the 1950s. During the 20-yr period of January 1957 through December 1976, a large number of universities in the United States and 1 in Canada contributed almost 150 papers on a variety of calf-related topics. These topics included genetics, physiology of the calf, review of calf immunity, antibiotic feeding, and milk replacer ingredients. This became the golden era of calf rumen development studies, which also engendered studies of calf starter rations and ingredients. A classic review of management, feeding, and housing studies summarized research related to calf feeding and management systems up to that point with an emphasis on maintaining calf growth and health while reducing labor and feed costs. It was also during this period that metric measurements replaced English units. In the 20-yr period from 1977 to 1996, more than 400 articles on calf nutrition and management were published in JDS. With the growing research interest in calves, a paper outlining standardized procedures for conducting and reporting data from calf experiments was first published. A very active area of calf nutrition research from the late 1970s to the mid 1980s was colostrum quality, feeding, and preservation; more than 60 such research articles were published in the journal during this time. Various nonmilk protein sources were evaluated. Extensive studies were done evaluating trace and major mineral requirements in calves along with some vitamin studies. Throughout the 1970s, 1980s, and 1990s, the primary objective of most calf research was how to wean healthy, adequately grown calves at an early age-generally less than 30 d of age. This program was reviewed in a 1979 publication. Research on calf starter ingredients, nutrient composition, and additives was minimal in the 1980s and 1990s given the importance of starter intake to the success of early weaning, but the role of water intake in starter intake and growth was established. Research on issues with calves continued to increase during the last 20-yr period as evidenced by publication of more than 580 articles in JDS as well as many more in other refereed journals. In addition to papers contributed by several universities in the United States and Canada, the number of papers authored by scientists at universities and institutes in other countries increased dramatically during this period. Factors influencing colostral antibody absorption, heat treatment of colostrum, and efficacy of colostrum supplements and replacers were reported. Most studies in this period related to nutrition. Studies were published supporting greater neonatal growth rates from feeding more milk replacer but with a higher crude protein content than traditional. Protein energy effects on growth and body composition were evaluated in concert with greater growth rates. Milk and nonmilk protein sources in milk replacers along with AA supplementation were evaluated. Limited studies were done with fat sources and fatty acid supplementation along with trace minerals and fat-soluble vitamins. Waste milk feeding and heat treatment became more prevalent. Studies established starter ingredient palatability and use of forage when fed with pelleted starters. With the advent of automatic milk and milk replacer feeders, factors influencing how and when to wean were established. Research programs established factors affecting calf behavior and welfare. Several databases were evaluated along with various published studies, and established calf growth during the first 2 mo was subsequently reflected in first- and later-lactation milk production of those calves. A new area of calf research that emerged from 1997 on was the effects of maternal environment and nutrition on calf health, growth, and future productivity. From a mechanistic standpoint, the field of epigenetics seems likely to explain many of these phenomena. Some possibilities for future calf nutrition and management were elaborated.

Review: Utilization of yeast of Saccharomyces cerevisiae origin in artificially raised calves

Yeast of Saccharomyces cerevisiae (SCY) origin has over long time been incorporated into domestic animal diets. In calves, several products have offered improved performance and health. Although several types of research have been completed, the mode of action of SCY is not clear in calves. Under this review, we have highlighted the works available in the literature on the use of SCY in calves performance, health, immunity, and the gut environment. Both active live yeast and yeast culture have positive effects on growth, rumen, small intestines, immunity and general health of the calf. Specifically, SCY can improve DMI, growth, feed efficiency and reduce diarrhea in calves. Furthermore, subtle improvements are seen in rumen fermentation (increased butyrate production) and rumen papillae growth. These positive results are, however, more pronounced in calves that are under stress or exposed to significant levels of disease-causing agents. There is a need for further research in areas such as gut morphology, gut microbiology and immunity using latest molecular methods to fully understand how SCY helps the growth and development of calves.

Stress, immunity, and the management of calves

Despite many advances in management and housing of dairy calves, 1 in 10 US dairy heifers die before weaning. A better understanding of the internal and external stimuli that contribute to the physiological and behavioral responses of calves to stressors is needed to reduce the risk of morbidity and mortality. Feeding calves their first meal is crucial, as successful passive transfer reduces the risk of mortality and morbidity. Sexually dimorphic immune and stress responses appear to be present in young cattle, but more research is needed to determine if this is caused by human bias for female calves. After that first feeding, 1 in 10 heifers and most bull calves in the United States are transported to specialized calf-raising facilities, yet information is lacking on the newborn calf stress response during transit. Whether calves are raised on site or at a calf ranch, individual housing systems are commonly used in the United States to reduce the risk of pathogen exposure and provide individual feeding and healthcare. However, health, growth, and social implications may be present for calves in alternative systems with greater space allowance than conventional systems or group housing. Disbudding and castration are typically performed at an early age for dairy calves during the pre-wean stage. These stressors often take place when the calf has decreased passive transfer of Ig and immunity is developing. Availability of pain mitigation through anesthetics and analgesics is limited, but evidence indicates that analgesics attenuate suppressed leukocyte function during these procedures. Solid-feed intake is a primary measure for determining weaning readiness, but some milk replacer formulas may influence the calf's oral behaviors before weaning; therefore, alternate weaning methods may need to coincide with alternate milk replacer formulas. The calf's behavioral and stress response at weaning may influence its immunity during the transition from individual to group housing (commingling). Alternate commingling strategies and nutritional supplements may help with this transition, but more research is needed to explore feasible alternatives. Optimizing the calf's health and well-being at these early stages may improve its long-term health and welfare.