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Hydrogenated fat-embedded calcium gluconate (HFCG), a prebiotic mixture designed to target the hindgut, has improved milk and component yields when supplemented in mid-lactation cows, likely due to improved hindgut health. The objective of this study was to evaluate production responses to HFCG when fed to dairy cattle over a full lactation. Seventy-four Holstein cows (21 primiparous, 53 multiparous) were used in a randomized complete block design comparing supplementation with HFCG (approximately 16 g/day supplement delivering approximately 6.4 g active ingredient) to a negative control from approximately 21 days prior to calving until end of lactation. In multiparous cattle supplemented with HFCG, average daily milk protein yield ( P = 0.037) was increased during the first 8 weeks of lactation, while average daily yields of milk fat, and fat- and energy-corrected milk tended ( P ≤ 0.075) to increase over the same period of time. Increased yields were likely supported by the concurrent increase in dry matter intake ( P = 0.036). Future work is needed to characterize the mode of action of this product within both the hindgut lumen and host, as well as investigate the potential differential responses between primiparous and multiparous animals over the course of lactation.

A variety of measures are currently used to evaluate feed efficiency in livestock, with some of the most popular being the linear regression of nutrient intake on the various energy sinks of the cohort being evaluated. The adoption of novel on-farm technologies has greatly increased the breadth and depth of data being collected on a daily basis, which creates the opportunity for the implementation of more advanced feed efficiency models. The objectives of the current study were to leverage data collected using high-throughput biometric technologies to evaluate changes of early-lactation feed efficiency on a daily basis and to develop a novel measure of feed efficiency based on the NRC net energy model. Daily records of nutrient intake, fat- and protein-corrected milk yield, body weight, and body condition score were used to model 7 different indices of feed efficiency (gross feed efficiency, return over feed costs, residual feed intake, residual net energy intake, and net energy efficiencies of lactation, maintenance, and body reserve flux) in primiparous Holstein heifers (n = 40) from 0 to 150 d in milk. We observed that feed efficiency was dynamic and fluctuated over the course of the experimental period regardless of the efficiency measure used, but most measures followed similar trends in changes of efficiency on a day-to-day basis. Of the measures evaluated, return over feed costs would be most suited for management purposes due to practicality and simplicity, whereas other measures, such as the efficiency of net energy flux to and from body reserves, present potential targets for inclusion in breeding goals. Net energy efficiency of lactation was estimated to have higher repeatability compared with residual feed or energy intake, which may reduce the time required to estimate whole-lactation efficiency. Because decreased net energy balance was strongly correlated with increased efficiency for all indices evaluated, future work investigating the associations of feed efficiency with the magnitude and duration of negative energy balance is warranted.

Genetic selection for improved feed efficiency in dairy cattle has received renewed attention over the last decade to address the needs of a growing global population. As milk yield is a critical component of feed efficiency metrics in dairy animals, our objective was to evaluate the associations between feed efficiency in primiparous Holstein cattle and parameters of a mathematical model describing individual lactation curves. The Dijkstra lactation curve model was fit to individual lactation records from 34 Holstein heifers with previously estimated measures of feed efficiency. We found that the optimal fit of the Dijkstra model was achieved using daily milk yield records up to 21 d in milk to capture the rise to peak milk yield and using monthly dairy herd improvement records for the remainder of lactation to accurately characterize lactation persistency. In the period of lactation before peak milk yield, improved feed efficiency was associated with a faster increase in daily milk yield over a shorter period of time at the expense of increased mobilization of body reserves; this serves to reinforce the concept that dairy cattle are primarily capital breeders versus income breeders. Feed efficiency in the period following peak lactation, as measured by gross feed efficiency, return over feed costs, and net energy efficiency of lactation, was positively associated with higher peak milk yield. The findings in early lactation suggest that estimates of feed efficiency could be improved by evaluating feed efficiency relative to conception, rather than parturition and lactation, to better account for the energy stored and released from body reserves in capital breeding.

There is growing evidence suggesting that by improving gut integrity and function, less energy is partitioned toward immune responses related to xenobiotic infiltration, sparing energy for productive purposes. Gluconic acid and its salts have previously shown prebiotic effects in the lower gut of nonruminant animals, where they serve as a precursor for butyrate, although evidence in ruminants is limited. Butyrate and its fermentative precursors have demonstrated multiple beneficial effects to gastrointestinal ecology, morphology, and function, such as the stimulation of epithelial cell proliferation and improvement of gut barrier function and ecology. The objective of this study was to evaluate changes in milk production, milk fatty acid composition, and fecal and blood parameters in lactating dairy cattle fed a hydrogenated fat-embedded calcium gluconate (HFCG) supplement designed to target the hindgut for calcium gluconate delivery. In addition, the effects of a compound feed processing method (i.e., incorporated into a mash or an extruded pellet) were tested to evaluate the effect of extrusion on product efficacy. Forty-five lactating Holstein cows at approximately 165 d in milk were used in a 3 × 3 Latin square consisting of three 28-d periods, during which animals were offered a basal ration mixed with 3 different compound feeds: a negative control in mash form containing no HFCG, or the HFCG supplement fed at a target rate of 16 g/d, delivered in either a mash or pelleted form. Supplementation of HFCG tended to increase yields of milk fat and fat- and energy-corrected milk. Total yields and concentrations of milk fatty acids ≥18 carbons in length tended to increase in response to HFCG. Plasma nonesterified fatty acids and milk urea increased in HFCG treatments. No differences were observed in fecal pH or fecal concentrations of volatile fatty acids, with the exception of isobutyrate, which decreased in HFCG-fed cows. Changes in milk fatty acid profile suggest that increased milk fat yield was driven by increased incorporation of preformed fatty acids, supported by increased circulating nonesterified fatty acid. Future research investigating the mode of action of HFCG at the level of the hindgut epithelium is warranted, as measured fecal parameters showed no response to treatment.

Fat-embedded calcium gluconate fed as a dietary supplement has previously been shown to increase milk and component yields in lactating dairy cattle in controlled experimental settings. These responses are thought to be due to improvements in gut barrier function and health driven by increased butyrate supply from the fermentation of calcium gluconate in the hindgut. The objectives of the current study were to validate the effects of a fat-embedded calcium gluconate supplement offered during late gestation and early lactation on milk production and milk component yields in a commercial setting. From April to December 2019, 151 multiparous Holstein-Friesian dairy cows were assigned to one of four treatment sequences in a randomized complete block design within a 2 x 2 factorial design (negative control or supplement prepartum, and negative control or supplement postpartum). Outcomes pertaining to milk production, component yields and health parameters were recorded for the first 100 days of lactation. Yields of milk and all components increased (P ≤ 0.045) in response to postpartum supplementation, in agreement with previous studies. Milk protein content was 0.03% lower (P = 0.003) in animals receiving the supplement prepartum. Additionally, prepartum supplementation diminished the lactation performance response relative to animals receiving supplementation in the postpartum period only; lactation performance was partially ameliorated by subsequent postpartum supplementation. Overall, these results support previous work examining the lactation performance response to fat-embedded calcium gluconate supplementation in dairy cattle. Future controlled studies examining the effects of prepartum supplementation on subsequent lactation performance are warranted.

Simple Summary It is well established that the functions of the gastrointestinal tract go beyond the digestion and absorption of nutrients. For instance, its constant contact with the gastrointestinal microbes and components of the diet makes it a major player within the immune system. Preserving the gut’s barrier function is essential to maintaining overall health and subsequently performance in farm animals. In cattle, multiple factors throughout their productive cycle can have negative consequences on gut health, including dietary changes. Most research in this topic has focused on rumen health, due to its critical role in digestion in bovines. However, it is increasingly evident that other sections of the gastrointestinal tract, such as the large intestine (also referred to as the hindgut), are similarly impacted by the same factors. Nutritional strategies aimed to promote rumen health have proven beneficial for overall health and performance in bovines. Targeting the hindgut might represent a window of opportunity for further improvement. Abstract An adequate gastrointestinal barrier function is essential to preserve animal health and well-being. Suboptimal gut health results in the translocation of contents from the gastrointestinal lumen across the epithelium, inducing local and systemic inflammatory responses. Inflammation is characterized by high energetic and nutrient requirements, which diverts resources away from production. Further, barrier function defects and inflammation have been both associated with several metabolic diseases in dairy cattle and liver abscesses in feedlots. The gastrointestinal tract is sensitive to several factors intrinsic to the productive cycles of dairy and beef cattle. Among them, high grain diets, commonly fed to support lactation and growth, are potentially detrimental for rumen health due to their increased fermentability, representing the main risk factor for the development of acidosis. Furthermore, the increase in dietary starch associated with such rations frequently results in an increase in the bypass fraction reaching distal sections of the intestine. The effects of high grain diets in the hindgut are comparable to those in the rumen and, thus, hindgut acidosis likely plays a role in grain overload syndrome. However, the relative contribution of the hindgut to this syndrome remains unknown. Nutritional strategies designed to support hindgut health might represent an opportunity to sustain health and performance in bovines.

The economic importance of genetically improving feed efficiency has been recognized by cattle producers worldwide. It has the potential to considerably reduce costs, minimize environmental impact, optimize land and resource use efficiency, and improve the overall cattle industry’s profitability. Feed efficiency is a genetically complex trait that can be described as units of product output (e.g., milk yield) per unit of feed input. The main objective of this review paper is to present an overview of the main genetic and physiological mechanisms underlying feed utilization in ruminants and the process towards implementation of genomic selection for feed efficiency in dairy cattle. In summary, feed efficiency can be improved via numerous metabolic pathways and biological mechanisms through genetic selection. Various studies have indicated that feed efficiency is heritable, and genomic selection can be successfully implemented in dairy cattle with a large enough training population. In this context, some organizations have worked collaboratively to do research and develop training populations for successful implementation of joint international genomic evaluations. The integration of “-omics” technologies, further investments in high-throughput phenotyping, and identification of novel indicator traits will also be paramount in maximizing the rates of genetic progress for feed efficiency in dairy cattle worldwide.

Several beneficial effects have been observed in the gastrointestinal tract in response to the provision of short-chain fatty acids such as butyrate, including the improvement of gut barrier function, stimulation of epithelial cell proliferation and gastrointestinal homeostasis. By improving gut barrier integrity, it is possible that less energy would be spent mounting an immune response against infiltrating xenobiotic compounds, allowing for more energy to be partitioned towards productive activities, such as milk synthesis. Previous work has demonstrated that gluconic acid and its salts have a prebiotic effect in the lower gut in monogastric animals, where it acts as a substrate for butyrate synthesis, with new data suggesting a similar response in dairy cattle. The objective of this study was to evaluate the effects of supplementation of a fat-embedded calcium gluconate product on milk production in dairy cattle. Lactating heifers (n = 22) and cows (n = 53) were offered either a total mixed ration supplemented with 0.07% fat-embedded calcium gluconate or a negative control ration over the course of a full lactation. Milk production and dry matter intake were recorded daily, while milk composition was determined at regular intervals over the lactation. Cows receiving the supplement displayed significant (P ≤ 0.046) increases in milk and component yields, while consuming 1 kg DM/d more during lactation compared to control. Heifers receiving the supplement displayed decreased (P ≤ 0.044) yield of milk fat and fat-corrected milk, 0.09% increased milk protein content, and decreased feed efficiency. Overall, the results in multiparous animals are consistent with previous work examining calcium gluconate. Further work is needed to characterize the differential response in heifers.

Feed efficiency has been widely studied in many areas of dairy science and is currently seeing renewed interest in the field of breeding and genetics. A critical part of determining how efficiently an animal utilizes feed is accurately measuring individual dry matter (DM) intake. Currently, multiple methods are used to measure feed intake or determine the DM content of that feed, resulting in different levels of accuracy of measurement. Furthermore, the scale at which data need to be collected for use in genetic analyses makes some methodologies impractical. This systematic review aims to provide an overview of the current methodologies used to measure both feed intake in ruminants and DM content of feedstuffs, current methods to predict individual DM intake, and applications of large-scale intake measurements. Overall, advances in milk spectral data analysis present a promising method of estimating individual DM intake on a herd scale with further validation of prediction models. Although measurements of individual feed intake rely on the same underlying principle, the methods selected are largely dictated by the costs of capital, labor, and necessary analyses. Finally, DM methodologies were synthesized into a comprehensive protocol for use in a variety of feedstuffs.

Feed efficiency is a trait of growing importance in the field of dairy cattle breeding as feed is often the single largest expense in dairy production systems. However, biological underpinnings of this trait have yet to be definitively characterized. The objective of this study was to identify gene networks that exhibited correlated expression patterns in dairy cattle classified as either high- or low-feed efficiency based on residual feed intake (RFI; kg/d). Data used for analyses was obtained from a previous study and accessed through a publicly-available repository (NCBI GEO: GSE92398). Transcriptome data generated using RNA-Sequencing technology was available from two sets of liver biopsies performed on 19 dairy cattle (10 Jersey & 9 Holstein). Animals of both breeds were selected from a research herd based on extreme RFI and allocated to two groups: HIGH feed efficiency (Holstein [n = 5], Jersey [n = 5]) and LOW feed efficiency (Holstein [n = 4], Jersey [n = 5]). Weighted gene co-expression networks (WGCN) were estimated using the WGCNA package in R for high- and low-feed efficiency groups to identify modules of co-expressed genes exclusively present in either of the groups. Twenty-nine and 38 modules were identified as uniquely co-expressed in high- and low-feed efficiency groups, respectively. In the high-feed efficiency group, modules of co-expressed genes were composed of 4336 genes that play crucial roles in biological processes related to feed efficiency, such as regulation of mitochondrial metabolism. In the low-feed efficiency group, 3940 genes responsible for regulation of carbohydrate and protein absorption were found to be in networks differentially co-expressed vs. high efficiency group co-expression networks. Genes involved in uniquely co-expressed networks and the positional markers located within those candidate genes will be further analyzed to elucidate functional relationships of these genes and how they contribute to feed efficiency in dairy cattle.

We report that protein phosphorylation is involved in the control of starch metabolism in Arabidopsis leaves at night. sex4 (starch excess 4) mutants, which have strongly reduced rates of starch metabolism, lack a protein predicted to be a dual specificity protein phosphatase. We have shown that this protein is chloroplastic and can bind to glucans and have presented evidence that it acts to regulate the initial steps of starch degradation at the granule surface. Remarkably, the most closely related protein to SEX4 outside the plant kingdom is laforin, a glucan-binding protein phosphatase required for the metabolism of the mammalian storage carbohydrate glycogen and implicated in a severe form of epilepsy (Lafora disease) in humans.

A broadband MBE GaAs PIN/NIP diode limiter has demonstrated 15 dB of isolation with a +32.5 dBm input signal while maintaining less than 0.25 dB of small-signal insertion loss from 0.05 GHz to 14 GHz. These results were obtained by incorporating vertical GaAs PIN/NIP diodes in a shunt-loaded microstrip configuration.

A broadband, monolithic, single-pole, sixteen-throw (SP16T) switch has been fabricated using GaAs vertical PIN diodes. The SP16T switch features less than 4.5-dB insertion loss with greater than 35-dB isolation across the 2-20-GHz band. A novel de-embedding scheme used for switch characterization is also introduced. >

A description is given of monolithic GaAs p-i-n diode limiter circuits that have demonstrated 20 dB of variable attenuation at X-band and Ka-band while maintaining under 1.5:1 input voltage standing-wave ratio (VSWR). Insertion loss is 0.5-dB at 10 GHz and 1.4-dB at 36.5 GHz in the 0-mA bias condition. Passive limiting provides 7-dB of isolation at radio frequency (RF) powers up to 1.5 W (30% duty cycle). The process used to fabricate the variable attenuation limiter is compatible with FET circuits, allowing integration of other MMIC components on the same substrate for future single-chip radar front ends. Several of these circuits have been fabricated and RF tested. Fabrication, circuit design, and RF performance are discussed. >

A new GaAs device developed for use in microwave monolithic control circuitry has been demonstrated. Known as a CFET, for Control Field Effect Transistor, this device eliminates the need for a conventional submicron gate by achieving control by use of a gate located behind the source-drain channel. The resulting capacitance is smaller than a conventional MESEET, resulting in a figure of merit of 800 GHz as compared to 250 GHz for a conventional MESFET. The device capabilities are demonstrated by measured performance of a SPDT switch providing 0.35-dB insertion loss and 20-dB isolation over the DC -10.0-GHz frequency band. >

Doramectin, 25-cyclohexyl-5-O-demethyl-25-de(l-methylpropyl)avermectin A1a, was selected as the best of a series of novel avermectins prepared by mutational biosynthesis. The primary evaluation of its in vivo antiparasitic activity was carried out using a rat Trichostrongylus colubriformis model and a rabbit Psoroptes cuniculi model. In each case the new avermectin performed favourably relative to dihydroavermectin B1a (DHAVM), the major component of ivermectin. Doramectin was extensively evaluated in cattle using an experimental micelle formulation, proving highly effective in cattle infected with Ostertagia ostertagi, Cooperia oncophora and Dictyocaulus viviparus when administered subcutaneously at 200 micrograms kg-1. The plasma pharmacokinetic characteristics of doramectin in cattle following intravenous administration revealed a plasma half-life of approximately 89 h. In the micelle formulation, doramectin administered subcutaneously at 400 micrograms kg-1 provided persistent activity against infection of cattle with C. oncophora and O. ostertagi for at least 8 and 12 days respectively.