V. Pereira

Relationship among blood indicators of lipomobilization and hepatic function during early lactation in high-yielding dairy cows

Blood indicators are used as a tool to diagnose metabolic disorders. The present work was conducted to study the relationships among blood indicators of lipomobilization and hepatic function in high-yielding dairy cows. Two groups of Holstein cows were studied: 27 early lactation cows and 14 mid lactation cows from four different herds with similar husbandry characteristics in Galicia, Spain. Blood samples were obtained to measure beta-hydroxybutyrate (BHB), non-esterified fatty acids (NEFA), triglycerides (TG), and the activity of aspartate transaminase (AST) and gamma-glutamyl transferase. Cows in early lactation had higher levels of BHB and NEFA than mid lactation cows. High lipomobilization (NEFA > 400 µmol/L) was detected in 67% and 7% of early lactation and mid lactation cows, respectively, while subclinical ketosis (BHB > 1.2 mmol/L) was detected in 41% and 28% of the early lactation and lactation cows, respectively. TG concentrations were low in all cows suffering subclinical ketosis and in 61% of the cows with high lipomobilization. During early lactation, 30% of cows suffered hepatic lipidosis as detected by levels of AST. Compromised hepatic function was observed in early lactation cows as shown by lower concentrations of glucose, total protein, and urea.

Effect of Supplementation with Antioxidants on the Quality of Bovine Milk and Meat Production

From a clinical point of view, oxidative stress (OS) is considered the primary cause of numerous metabolic processes in transition cow. Thus, the addition of antioxidants has been considered a palliative or preventive treatment. But beyond the clinical perspective, antioxidant supplementation provides an added value to the product obtained being either milk or meat. This paper reviews the beneficial aspects that provide antioxidant supplementation on quality of both products and that fit into the new concept that the consumer has a functional and healthy food. Our approach is from a veterinary standpoint, by reviewing the studies conducted to date and the new perspectives that are interesting and need to be studied in the following years. One of the highlights is that sustainable farming, one in which production is combined with animal health, also impacts positively on the quality of the final products, with beneficial antioxidant properties to human health.

Influence of grain processing on acid-base balance in feedlot steers

Grain processing (e.g. grinding, steaming, pelleting, flaking) has been reported to modify the incidence of ruminal disturbances in feedlot cattle. This study investigated the effects of two grain processing methods widely used in Spanish feedlots (grinding and pelleting) on animal performance, blood acid–base balance, blood electrolyte levels and serum lactate in a 140-day feedlot experiment with double-muscled Belgian Blue steers. The main aim of the study was to evaluate the way in which these two feeds modify blood acid–base balance, which is closely associated with ruminal pH. In light of our results we conclude that the animals that received the pelleted feed showed a more stable acid–base balance over time than those fed a ground feed. Nevertheless, higher levels of L-lactate and lower base excess (BE) and HCO3− values for cattle fed pelleted grain reflect a greater risk of grain-acid overload.

Effects of monensin and yeast supplementation on blood acid-base balance in finishing feedlot steers fed a high-grain, high-protein diet

The aim of this study was to evaluate the effects of two dietary supplements (monensin and a live yeast culture) on acid-base balance in steers maintained in a commercial feedlot system, considering effects over the finishing productive cycle. Steers (no. =42) were allotted randomly to one of the three study groups: (1) control group (no supplementation, C), (2) monensin supplementation (MON), and (3) live Saccharomyces cerevisiae strain 47 supplementation (SACC). Venous blood samples were collected for the measurement of acid-base parameters and l-lactate. Production parameters were also used as a complementary tool for understanding the internal changes associated with supplementation. During the finishing period, MON steers tended to gain more efficiently than C and SACC steers. In the C group, the finishing-period diet caused a progressive decline in blood bases, in line with the high-grain diet consumption. In contrast, supplemented animals did not show this trend, although lower HCO 3 − and base excess values were registered in SACC steers than in MON, indicating that ionophore supplementation is less effective for reducing blood base consumption than yeast supplementation. In our study, the lack of the expected response to yeast supplementation may be attributable to the high crude protein content of the ration, a common feature of commercial feedlot industries.

Effect of moderate Cu supplementation on serum metabolites, enzymes and redox state in feedlot calves

The aim of this investigation was to evaluate whether, in the nutritional management of commercial feedlots, copper (Cu) supplementation is justified to maintain the physiological requirements. This study compared beef calves fed concentrates with an average Cu basal content of 5 and 8 mg/kg in growing and finishing periods (10 animals) or supplemented with 15 mg/kg for each phase (20 animals) as regards production indices, metabolic parameters [glucose, nonesterified fatty acids (NEFA), cholesterol, serum urea nitrogen (SUN), creatinine, total serum protein (TSP), albumin, aspartate transaminase (AST) and γ-glutamyl transferase (GGT)] and markers of oxidative stress (reactive oxygen species (ROS) and serum antioxidant capacity (SAC)). Data were recorded at ages 12, 24 and 36 weeks. In general, Cu supplementation was neither detrimental nor beneficial for animal health and performance, and the levels of the measured metabolites and enzymes were within their normal ranges stated for feedlot with the same management during the whole study. However, in keeping with reported higher hepatic Cu levels at slaughter, animals on supplemented feed had higher GGT activities at the end of the finishing stage, although the difference was not statistically significant. On the other hand, lower SAC levels at the end of the growing period in the supplemented group suggest the possibility of a positive effect of Cu supplementation on redox state. Further research is necessary to clarify the potential role of Cu in limiting the ROS production associated with fattening diets, and to evaluate the hepatobiliary consequences of supplementation, including hepatic Cu accumulation.

Effects of malate supplementation on acid-base balance and productive performance in growing/finishing bull calves fed a high-grain diet

This study investigated the effects of malate supplementation on blood acid-base balance and serum lactate levels in a 137-day feedlot experiment with bull calves. Animals were allotted to one of two experimental groups: (1) A control group (no supplementation), and (2) a group receiving a salt of DL-malic acid. Blood pH, pCO2, HCO3 −, base excess, serum L-lactate and productivity parameters were evaluated. Our data reveal that under the conditions of the present experiment malate supplementation did not have any significant effect on productivity parameters by comparison with non-supplemented animals. As regards acid-base balance, no significant effects attributable only to malate were observed. In conclusion, the time-course and the overall means of serum L-lactate for both groups in both growing and finishing periods (0.44 ± 0.04 mmol/l and 0.39 ± 0.02 mmol/l, respectively, for control animal; and 0.54 ± 0.03 mmol/l and 0.49 ± 0.01 mmol/l, respectively, for supplemented animals) suggests that malate does not have any beneficial effects in animals fed a diet of similar characteristics to that given in this study.

Trace Element Concentrations in Beef Cattle Related to the Breed Aptitude

Animal feed has traditionally been supplemented with trace elements at dietary concentrations well above physiological needs. However, environmental concerns have led to calls for better adjustment of mineral supplementation to actual physiological needs and, in this context, consideration of breed-related differences in trace element requirements. The aim of this study was to analyze trace element concentrations in the main breeds used for intensive beef production in northern Spain (Holstein-Friesian [HF], Galician Blonde [GB], and GB × HF cross). Samples of blood, internal organs, and muscle were obtained at slaughter from 10 HF, GB, and GB × HF cross calves in the same feedlot. Overall, trace element concentrations in serum and internal organs were within adequate ranges and did not differ between those of breeds, suggesting that trace mineral supplementation was adequate in all groups. The only exception to this was copper, and hepatic copper concentrations were above adequate levels in all calves. This was particularly evident in the HF calves, and the maximum recommended level for human consumption was exceeded in 90% of these animals. Copper, iron, manganese, selenium, and zinc concentrations in muscle were significantly higher in the HF than those in the GB calves, with intermediate values for the crosses. These breed-related differences in trace element concentrations in the muscle may be related to lower muscle mass and/or higher hepatic activity in the HF (dairy) calves than in GB (beef) calves. As meat is an essential source of highly available trace elements in human diets, breed-related differences in trace element concentrations in meat deserve further investigation.

Preliminary results in the redox balance in healthy cats: influence of age and gender

Oxidative stress (OS) impairs organic function and is considered causally related to cellular senescence and death. This study aims to evaluate if the redox balance varies in relation to age and gender in healthy cats. To quantify the oxidative status of this species we determined the oxidative damage as serum reactive oxygen metabolites (ROM) and the total serum antioxidant capacity (SAC). In addition, we used the ratio of ROM to SAC as a measure of the oxidative balance, with higher values meaning higher oxidative stress (oxidative stress index). Our results suggest that the male population is at oxidative risk when compared with females, especially between the age of 2 and 7 years. Nutritional strategies in this population looking for additional antioxidant support would probably avoid the oxidative stress status that predisposes to chronic processes in senior male cats. Further clinical trials in this field are recommended.

Importance of breed aptitude (beef or dairy) in determining trace element concentrations in bovine muscles

The aim of this study was to determine the concentrations of various trace elements in muscles with different oxidative/glycolytic profiles (cardiac [CA]; diaphragm [DI], as oxidative; trapezius [TR], as intermediate oxidative/glycolytic; and semimembranosus [SM], as glycolytic muscle) of ten dairy-aptitude (Holstein-Friesian, HF), ten beef-aptitude (Galician Blonde, GB) and ten cross-breed (GBxHF) calves. The type of muscle was a highly significant factor in relation to the concentrations of all elements, whereas breed was only significant for Fe, Mn and Zn in the SM muscle. The concentrations of the main trace elements (Cu, Fe, Se and Zn) were significantly lower in GB and GBxHF than in HF, that were mainly associated with differences in the oxidative/glycolytic profile, probably due to the muscular hypertrophy characteristic of heavily muscled breeds. The pattern of distribution was similar in all breeds, with significantly higher concentrations in the CA muscle, followed by the DI; trace element concentrations in the SM and TR muscles were very similar.

Subcellular distribution of hepatic copper in beef cattle receiving high copper supplementation

Previous studies of intensively reared cattle in NW Spain have reported significantly higher copper (Cu) accumulation in the liver in Holstein-Friesian (HF) animals than in Galician Blonde (GB) or GBxHF crosses when receiving a diet supplemented at the maximum Cu concentrations allowed in the EU legislation (35mg/kg). The present study aimed to evaluate whether this difference is due to the pattern of subcellular accumulation of Cu in the liver. For this purpose, liver samples from 10 GB, 9 HF and 10 GBxHF young bulls were analysed to determine the content of metallothionein (MT) and Cu and zinc (Zn) (in the liver (Cu-liver and Zn-liver) and bound to metallothionein (Cu-MT and Zn-MT)). The Cu distribution within the main subcellular compartments (nuclei, large granule, microsomes and cytosol) was also determined. Even though HF animals showed significantly higher (P<0.05) Cu concentrations in the liver (161±10mg/kg wet weight) compared with GB (132±8mg/kg), no breed-related differences were observed for any of the parameters considered in this study. Overall, the pattern of hepatic subcellular accumulation was similar to that previously described in cattle: (i) MT concentrations were lower than in other animal species but strongly related to hepatic Zn; (ii) a low proportion of Cu (6.61%) was bound to MT but this was strongly and negatively related to the Cu:Zn ratio in the liver cell; and (iii) the highest proportion of Cu (57.3%) was found in the large granule (lysosome containing) fraction. All these results indicate a low capacity of cattle to excrete Cu by the bile resulting in a high Cu accumulation in the liver cell.