Heat stress in dairy cattle – Some potential health risks associated with the nutritional management of the condition

Heat stress occurs when animals are exposed to environmental temperatures in excess of 25oC (the upper critical temperature), particularly in combination with high relative humidity or direct sunshine. Prevention is by providing plenty of good-quality drinking water, providing shade (natural or artificial), and using water sprinklers and/or fans. Changes to the diet, i.e., high energy density and low protein, are also beneficial and often implemented. However, there may be some potential risks associated with the nutritional management of heat stress in dairy cattle; i.e., the animals are at increased risk of developing subacute rumen acidosis, with ensuing laminitis/lameness, and displaced abomasum. This paper discusses how increasing the energy density of the diet (i.e., increasing the grain/forage ratio), as part of the nutritional management of heat stress, may put cows at greater risk of the above-mentioned digestive disorders.

PSXIV-14 Supplementation of high-grain diet with red osier dogwood affects in vitro digestibility and fermentation characteristics

Red osier dogwood (ROD) is a native shrub plant rich in phenolic compounds with antimicrobial properties. The objective of this study was to evaluate the effects of substituting barley silage with either raw ROD or ROD extract (RODE) in high-grain (HG) diet under a low media pH (5.8) on gas production (GP), dry matter (DM) disappearance (DMD) and fermentation characteristics in batch cultures. The study was a completely randomized design with 4 treatments: 1) control diet (10% barley silage and 90% barley concentrate, DM basis), control diet supplemented with 2) monensin (30 mg/kg diet DM; positive control), 3) substitution of 3% ROD or 4) 3% RODE for an equal portion of silage. Inoculum was obtained from 2 ruminally fistulated beef heifers offered the HG diet. Substrate ground (1 mm) was incubated for 24 h and the experiment repeated twice. The GP did not differ among treatments (147 ml/g DM), but the DMD differed (P < 0.02) at highest for control (69.4%), lowest for ROD (58.4%) and intermediate for other treatments (64.1%). Total volatile fatty acid (VFA) concentration (mM) tended (P< 0.08) to be lower with ROD (80.5) and monensin (80.1) than control (83.9). Acetate proportion was greater (P = 0.02) with ROD (46.2%) and RODE (46.9%) than control (42.4%) and monensin (42.3%). However, the propionate proportion was greater (P = 0.05) with monensin (32.1%) than other treatments (averaged 30.1%). Consequently, acetate to propionate ratio (A:P) of ROD (1.52) and RODE (1.56) was higher than monensin (1.32; P < 0.01) and control (1.44; P < 0.08). Differences in variables measured between ROD and RODE were minimal. These results indicated that the decreased DMD along with increased A:P with addition of ROD or RODE suggests that both ROD and RODE may be beneficial to HG fed cattle for reducing risk of rumen acidosis without negatively impacting fibre digestion.

Scientific Basis for the Treatment and Prevention of Large Abdominal Acidosis in Productive Cows

The article analyzes the results of clinical observations on the distribution and etiology, as well as experimental studies on the development of diagnostic and treatment-and-prophylactic measures of rumen acidosis in breeding cows in the conditions of farms of the republic.

Effects of a High-Grain Diet With a Buffering Agent on Milk Protein Synthesis in Lactating Goats

Chinese dairy industries have developed rapidly, providing consumers with high-quality sources of nutrition. However, many problems have also appeared during the development process, especially the low quality of milk. To improve milk quality, a large amount of concentrated feed is usually added to the diet within a certain period of time, which increases the milk production to a certain extent. However, long-term feeding with high-concentration feed can lead to subacute rumen acidosis. Therefore, the present study aimed to determine the effect of adding a buffer on subacute rumen acidosis, and the improvement of milk production and milk quality. We also aimed to study the mechanism of promoting mammary gland lactation. A total of 12 healthy mid-lactating goats were randomly divided into two groups, they were high-grain diet group (Control) and buffering agent group. To understand the effects of high-grain diets with buffers on amino acids in jugular blood and the effects of amino acids on milk protein synthesis, Milk-Testing™ Milkoscan 4000, commercial kits, and high-performance liquid chromatography (HPLC) measurements were integrated with the milk protein rate, the amino acid concentration in jugular venous blood samples, quantitative real-time PCR, comparative proteomics, and western blotting to study differentially expressed proteins and amino acids in mammary gland tissues of goats fed high-grain diets. Feeding lactating goats with buffering agent increased the percentage of milk protein in milk, significantly increased the amino acid content of jugular blood (p < 0.05), and increase the amino acid transporter levels in the mammary gland. Compared with the high-grain group, 2-dimensional electrophoresis technology, matrix-assisted laser desorption/ionization-time of flight/time of flight proteomics analyzer, and western blot analysis further verified that the expression levels of beta casein (CSN2) and lactoferrin (LF) proteins in the mammary glands of lactating goats were higher when fed a high-grain diets and buffers. The mechanism of increased milk protein synthesis was demonstrated to be related to the activation of mammalian target of rapamycin (mTOR) pathway signals.

Effect of Ginger Powder (Zingiber officinale) on Acid-Base Balance, Rumen and Blood Constituents in Healthy Egyptian Sheep

Medicinal herbs have been used for several thousand years in traditional medicine and are known to be inexpensive, effective, readily available, and safe to use, with almost no side effects. As no previous research focused on the effect of ginger powder (Zingiber officinale) on acid-base balance in sheep, the goal of this study was studying the effects of ginger (Zingiber officinale) powder on acid-base balance, rumen, and blood constituents. Ten Egyptian ewes were given ginger powder 500mg/kg bwt orally in the morning before feeding for 5 days. Blood and rumen juice samples were collected in the morning on 0 (control), 3rd, and 5th day before feeding. Results generally showed a significant increase in rumen fluid pH, WBCS, lymphocytes, MCH, and MCHC. Significant decrease in total volatile fatty acids, serum total protein, and globulin were recorded. Ginger maintained acid-base balance, rumen protozoa activity, total protozoa count, rumen ammonia concentration, RBCs, PCV, Hemoglobin, neutrophils, albumin, BUN, Creatinine, GGT, and AST within normal range. Depending on changes in blood and rumen constituents we may suggest a recommendation for using ginger supplementation as 500mg/kg bwt orally for 3-5days as an immune stimulant and in the treatment of rumen acidosis and respiratory affections in sheep.

Evaluation of liquid and powdered forms of polyclonal antibody preparation against Streptococcus bovis and Fusobacterium necrophorum in cattle adapted or not adapted to highly fermentable carbohydrate diets

Objective: Feed additives that modify rumen fermentation can be used to prevent metabolic disturbances such as acidosis and optimize beef cattle production. The study evaluated the effects of liquid and powdered forms of polyclonal antibody preparation (PAP) against <i>Streptococcus bovis</i> and Fusobacterium necrophorum on rumen fermentation parameters in ruminally cannulated non-lactating dairy cows that were adapted or unadapted to a high concentrate diet.Methods: A double 3×3 Latin square design was used with three PAP treatments (control, powdered, and liquid PAP) and two adaptation protocols (adapted, unadapted; applied to the square). Adapted animals were transitioned for 2 weeks from an all-forage to an 80% concentrate diet, while unadapted animals were switched abruptly.Results: Interactions between sampling time and adaptation were observed; 12 h after feeding, the adapted group had lower ruminal pH and greater total short chain fatty acid concentrations than the unadapted group, while the opposite was observed after 24 h. Acetate:propionate ratio, molar proportion of butyrate and ammonia nitrogen concentration were generally greater in adapted than unadapted cattle up to 36 h after feeding. Adaptation promoted 3.5 times the number of <i>Entodinium</i> protozoa but copy numbers of <i>Streptococcus bovis</i> and Fibrobacter succinogens genes in rumen fluid were not affected. However, neither liquid nor powdered forms of PAP altered rumen acidosis variables in adapted or unadapted animals.Conclusion: Adaptation of cattle to highly fermentable carbohydrate diets promoted a more stable ruminal environment, but PAP was not effective in this study in which no animal experienced acute or sub-acute rumen acidosis.

Disclosure of the Mechanisms of Metabolic Disorders in Highly Productive Cows as a Way to Improve Milk Production Technology

The aim of this study was to study the molecular mechanisms of metabolic disorders that develop in highly productive cows. It was found that in the blood serum of animals with subclinical ketosis (SCK), which are in the eighth month of pregnancy, the concentration of β-hydroxybutyrate is increased, the content of iron, calcium and phosphorus is reduced, its iron-binding capacity against the background of the absence of phenomena of hepatocellular insufficiency, violation of the integrity of hepatocytes, hypoplastic anemia. The aggravation of ketoacidosis in fresh cows with rumen acidosis is facilitated by the development of carbohydrate deficiency in them, due to their increased oxidation in the reactions of anaerobic glycolysis, accompanied by excessive catabolism of purine mononucleotides to uric acid. Excessive lipid peroxidation of membrane structures under conditions of increased catabolism of purine nucleotides, along with the accumulation of acylglycerols in the liver caused by cobalamin deficiency, leads to the development of syndromes of impaired hepatocyte integrity and hepatocellular insufficiency. A decrease in the liver's ability to store iron ions and synthesize proteins that provide an increase in the iron-binding capacity of blood plasma in conditions of cobalamin deficiency contributes to the development of hypoplastic anemia not only in cows, but also in calves born from them.

Instant Insights: Metabolic disorders in dairy cattle

This specially curated collection features four reviews of current and key research on metabolic disorders in dairy cattle. The first chapter reviews the prevalence, etiology and effects of ruminal acidosis, as well as ways to counteract it through regulation of ruminal pH. The chapter includes a case study on subacute rumen acidosis (SARA) in the post-partum phase of the transition period. The second chapter assesses the main pathways for rumen fermentation which is a major factor in efficient transformation of nutrients. It discusses factors influencing the efficiency of microbial growth as well as the interactions between rumen energy and nitrogen metabolism in ensuring efficient digestion and avoiding metabolic disorders. The third chapter investigates the genetics of improving feed intake efficiency which has significant potential in reducing metabolic disorders. The chapter reviews key challenges in developing genomic selection indices for feed intake, including recording feed intake, pooling genetic data and establishing genomic breeding values for feed efficiency. The fourth chapter discusses how cereal grains impact feed efficiency in cattle. It reviews how cereal grains can be used to improve feed efficiency and the microbiology of cereal grain fermentation. The chapter also discusses ways of avoiding acidosis and other negative feed effects.