Effects of a novel heat-treated protein and carbohydrate supplement on feed consumption, milk production, and cheese yield in early-lactation dairy cows.

Protein is an expensive component of the dairy cow diet, and overfeeding protein can have adverse economic and environmental impacts. Our objective was to maintain milk production and components while decreasing dietary crude protein (CP) through use of a heat-treated, rumen-resistant sugar amino acid complex (SAAC) as the Schiff base, as an addition to low-protein diets. Dietary treatments included a negative control [NC, 146 g of CP/kg of dry matter (DM)], a positive control (PC, 163 g of CP/kg of DM), and the NC supplemented with SAAC in lieu of some barley grain (SAAD, 151 g of CP/kg of DM). Diets were fed to 30 multiparous Holstein-Friesian dairy cows for the first 50 d postpartum. Dry matter intake (DMI) was determined daily. Milk yield and content of fat, protein, lactose, and casein were recorded weekly from wk 2 to 7 of lactation. The fixed effects of treatment, week, treatment × week, month of calving, and BCS at calving, and a random effect of cow, were analyzed using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC). The SAAD treatment had greater energy-corrected milk yield than did NC. The PC treatment had greater DMI than did NC, and SAAD tended to have greater DMI than did NC. We found significant treatment effects for fat percentage and yield. The NC and SAAD treatments had higher fat percentages than did PC, and SAAD had a higher fat yield than did the NC and PC treatments. Treatment effects were found for casein yield and percentage. We discovered a treatment effect for protein percentage and yield. The PC treatment had higher protein percentage than did NC and SAAD. The PC treatment had a higher protein yield than did NC, and analysis revealed no difference in protein yield between PC and SAAD. The SAAD treatment had higher total milk solids than did the NC treatment. Lactose yield tended to be higher in PC than in NC, and no differences were found between PC and NC and SAAD treatments. The PC treatment had a higher casein percentage than did NC and SAAD; however, the SAAD and PC treatments had higher casein yields than did NC. The PC treatment had a higher casein:fat ratio than did the NC and SAAD treatments. The NC and SAAD treatments had higher Cheddar cheese yields than did PC. We found no treatment × week interactions for any parameter. Supplementing low-protein dairy cow diets with a heat-treated, rumen-resistant SAAC caused beneficial effects by improving milk components and increasing cheese yield to levels similar to those found when feeding expensive and environmentally damaging high-protein diets.

A comparison of serum metabolic and production profiles of dairy cows that maintained or lost body condition 15 days before calving.

Body condition score (BCS) change is an indirect measure of energy balance. Energy balance before calving may affect production and health in the following lactation. It is likely that cows may experience BCS loss before calving due to negative energy balance. The objective of this study was to determine if loss of BCS 15d before calving affected milk production, BCS profile, and metabolic status during the transition period and early lactation. On d -15 to d 0 relative to calving, BCS was assessed (1=emaciated, 5=obese) for 98 Holstein-Friesian cows. The cows were divided into 2groups: those that did not lose BCS between d -15 and d 0 (maintained, BCS-M, n=55) and those that lost BCS from d -15 to d 0 (lost, BCS-L, n=43, average loss of 0.29±0.11 BCS). The fixed effects of BCS group, parity, week (day when analyzing milk production records), their interactions, and a random effect of cow were analyzed using PROC MIXED of SAS (SAS Institute Inc., Cary, NC). Before calving, BCS-L cows tended to have higher concentrations of nonesterified fatty acids than BCS-M cows (0.88 vs. 0.78mmol/L). After calving, BCS-L cows had higher nonesterified fatty acid concentrations in wk 1 (0.93 vs. 0.71mmol/L), wk 2 (0.84 vs. 0.69mmol/L), and wk 4 (0.81 vs. 0.63mmol/L) than BCS-M cows. The BCS-L cows had higher concentrations of ß-hydroxybutyrate (BHB) in wk 1 (0.72 vs. 0.57mmol/L), wk 2 (0.97 vs. 0.70mmol/L), and wk 4 (0.94 vs. 0.67mmol/L) compared with BCS-M cows. We detected significant reductions in insulin concentrations in BCS-L cows from wk -1 (2.23 vs. 1.37 µIU/mL) to wk 2 (1.68 vs. 0.89 µIU/mL) and wk 4 (2.21 vs 1.59 µIU/mL) compared with BCS-M cows. Prevalence of subclinical ketosis increased in BCS-L cows in wk 3 and 4 when BHB was ≥1.4mmol/L and in wk 1, 3, and 4 when BHB was ≥1.2mmol/L. In wk 1, BCS-L cows tended to have lower levels of calcium than BCS-M cows (2.33 vs. 2.27mmol/L). We found no differences between the groups of cows for milk yield and energy-corrected milk. The BCS-L cows had lower BCS up to 75d in lactation. Overall, BCS-L cows had higher somatic cell scores with an elevated somatic cell score on d 45, d 60, and d 75. There was an overall tendency for BCS-L cows to have higher fat yield and an overall significant increase in fat percentage. Overall, BCS-L cows had lower lactose percentage, with a reduction on d 60. This work shows that BCS loss before calving may have significant consequences for metabolic status, milk composition, somatic cell score, and BCS profile in dairy cows.

Reversal of a hallmark of brain ageing: lipofuscin accumulation.

The prospect of removing cellular deposits of lipofuscin is of considerable interest because they may contribute to age related functional decline and disease. Here, we use a decapod crustacean model to circumvent a number of problems inherent in previous studies on lipofuscin loss. We employ (a) validated lipofuscin quantification methods, (b) an in vivo context, (c) essentially natural environmental conditions and (d) a situation without accelerated production of residual material or (e) application of pharmacological compounds. We use a novel CNS biopsy technique that produces both an anti-ageing effect and also permits longitudinal sampling of individuals, thus (f) avoiding conventional purely cross-sectional population data that may suffer from selective mortality biases. We quantitatively demonstrate that lipofuscin, accrued through normal ageing, can be lost from neural tissue. The mechanism of loss probably involves exocytosis and possibly blood transport. If non-disruptive ways to accelerate lipofuscin removal can be found, our results suggest that therapeutic reversal of this most universal manifestation of cellular ageing may be possible.

Quantitative comparison of in situ lipofuscin concentration with soluble autofluorescence intensity in the crustacean brain.

The intensity of soluble 'lipofuscin-like' autofluorescences extracted from the brain of the freshwater crayfish, Cherax quadricarinatus, was compared with the concentration of morphological lipofuscin present in sections of the same tissue. This study represents the first quantitative demonstration that these soluble autofluorescences, previously attributable to lipofuscin or fluorescent age pigment (FAP), actually bear no quantitative relationship to it at all. This result confirms previous suspicions in the literature. In some cases the intensities of these unidentified soluble autofluorescences are positive linear or curvilinear functions of organ or body weight and, therefore, may give the misleading impression that they are related to age and derived from age pigment. It is strongly recommended that researchers, particularly on aquatic species, avoid using the original biochemical assay procedure for lipofuscin and its more recent modifications.

An alternative explanation for anomalies in "soluble lipofuscin" fluorescence data from insects, crustaceans, and other aquatic species.

Published attempts to extract lipofuscin from crustaceans and fish to assess age for fisheries research purposes have used essentially the same extraction methodology applied to insects, but have neither shown a conclusive age-dependence of spectrally similar fluorescence nor proved its association with lipofuscin. The reported lipofuscin solvent extraction method for fleshflies, Sarcophaga bullata, was manipulated by varying wash volume. This revealed that almost all age-dependent blue fluorescent material persisting in lipid fractions was actually pteridine-like. This finding was consistent with some previous independent results for Musca domestica. Examination of reported lipofuscin extraction protocols for other insects suggested that this problem was probably widespread. The pteridines are known to occur in unusually high amounts in insects, accumulating with age specifically in some members of this group by storage excretion, probably as a terrestrial water conservation strategy. In addition, there is growing evidence in the gerontological literature for other groups that solvent extracted blue fluorescence is not a true measure of lipofuscin content in tissues. These findings provide considerable insight into anomalies in putative lipofuscin fluorescence data between the insects and various aquatic species and suggest that there may be little basis for expectations of age-dependent fluorescence from aquatic species when the same gross extraction and crude purification methods are used.

Lipofuscin as a record of "rate of living" in an aquatic poikilotherm.

As an integral of oxidative metabolism and physiological age index, lipofuscin accumulation was used to evaluate assumptions underlying previous rejection of the rate of living theory of aging. Lipofuscin in the olfactory lobe cell mass of crayfish, Cherax quadricarinatus, was measured throughout life under a wide range of temperature regimes, using image analysis of fluorescence micrographs of brain sections. The relationship between temperature, chronological age, and rate of living, as indicated by lipofuscin accumulation rate, had a complex nonlinear three-dimensional structure, suggesting a thermal optimum, thermal mid-range metabolic compensation, and age-associated variation. The particular experimental window through which this response surface is viewed will have a profound effect on the outcome of life span experiments such as those previously used to test the rate of living theory. The results of this study further challenge assumptions leading to previous rejection of this theory.

A flow-cytometric method for quantification of neurolipofuscin and comparison with existing histological and biochemical approaches.

The ability to measure lipofuscin accumulation accurately is essential for understanding its role in physiological ageing and human disease, and for its recent use as an ecological tool for age determination. Existing quantification methods are problematic. In situ histological measurement by microscopy can be very precise but is labour intensive. Spectrofluorimetric measurement of whole lipid extracts is rapid but not sufficiently specific. A recent HPLC assay for the retinal pigment epithelium lipofuscin fluorophore, A2-E, is potentially both precise and rapid but not applicable to lipofuscin in other tissues, or from fixed samples. In this study, I explore the use of flow cytometry or fluorescence activated cell sorting (FACS) for specific quantification of lipofuscin granules in formalin-fixed CNS homogenates from lobsters (Homarus gammarus). Free neurolipofuscin granules were discriminated in FACS samples by their size distribution (forward scatter), distinctive orange autofluorescence (FL3) and refractive internal structure (side scatter). A quantitative neurolipofuscin index was developed, which was highly correlated with the microscopically measured neurolipofuscin concentration in the same tissue. Sample-processing rate was at least an order of magnitude greater for FACS than for quantitative microscopy but the latter yielded a much more precise estimate of neurolipofuscin concentration. While the FACS approach may be ideal where rapid handling and only semiquantitative results are required, loss of precision will preclude use in many ecological studies where the highest available resolution is needed. Further refinements to the FACS approach are possible but advanced histological methods for neurolipofuscin quantification remain the most reliable at this time.

Role of environmental temperature in aging and longevity: insights from neurolipofuscin.

The available evidence for thermal modulation of neurolipofuscin deposition in poikilotherms is reviewed here and additional data are contributed. Mainly decapod crustacean models are employed and neurolipofuscin is treated as an index of physiological aging. In all cases, neurolipofuscin accumulation rate is positively correlated with environmental temperature but there appears to be lowered sensitivity in the thermal mid-range, an 'optimum' temperature for neurolipofuscin accumulation and possibly age-associated variation. The geographical position of the population within the species' thermal range may determine sensitivity of the response. There is seasonal oscillation of neurolipofuscin accumulation rate, providing preliminary evidence for neurolipofuscin turnover with net loss in winter. Spatial and temporal thermal variations of similar magnitude appear to have comparable effects on neurolipofuscin accumulation rate. Such effects may be extreme, suggesting important implications for physiological aging even in homeotherms. Inter-specific comparisons indicate that species-specific neurolipofuscin accumulation rates are positively correlated with habitat temperature and inversely correlated with maximum lifespan and age at maturity. These findings help explain some well-known bioclimatic trends in maturation- and maximum body size, such as Bergmann's rule. They also highlight the fact that global warming is likely to cause significant changes in life history parameters, population dynamics and responses to exploitation for many species.