Commercial Calf Research Articles

Evaluation of the effects of oral colostrum supplementation during the first fourteen days on the health and performance of preweaned calves

Increasing concerns about antimicrobial resistance have led to the development and implementation of alternatives to antimicrobial use in animal production. The objective of this clinical trial was to determine the effect of colostrum supplementation of the milk replacer ration on morbidity, mortality, feed intake, and weight gain of preweaned calves. Ninety 1-d-old calves on each of 3 commercial calf ranches were randomly allocated to 1 of 3 groups. Treatment-group calves received 10g of supplemental immunoglobulin G (IgG) in the form of 70g of colostrum powder in the milk replacer twice daily for 14 d. The placebo-group calves received a nutritionally equivalent supplement lacking IgG in the milk replacer twice daily for 14 d. Control calves received milk replacer without supplements twice daily. Calves were housed in individual hutches and were weighed on d 1, 28, and 60. Serum was collected on d 2 for serum IgG determination. Daily health evaluations for the first 28 d of life were performed by study personnel blinded to treatment group assignment. Observed illness was treated based on health assessment, rectal temperature, and specific calf ranch protocols. Feed consumption (milk and grain) was recorded. Calves receiving supplemental colostrum had less diarrhea and received fewer antimicrobial treatments than control and placebo calves. The results indicated that calf diarrhea was associated with low serum IgG levels and low-weight calves. Grain consumption and weight gain over the first 28 d of life were significantly greater in colostrum-supplemented calves compared with control calves. No differences in mortality or respiratory disease incidence among groups were detected. Supplemental colostrum during the first 2 wk of life can reduce diarrheal disease in preweaned calves on calf ranches and thereby reduce the amount of antimicrobial treatments needed.

Effect of the number of concentrate feeding places per pen on performance, behavior, and welfare indicators of Friesian calves during the first month after arrival at the feedlot1

Seventy-two Friesian calves (BW = 102.0 +/- 1.8 kg) were bought from a commercial calf farm and distributed to a factorial arrangement of treatments in a complete block design with 3 treatments and 3 blocks of similar fasted BW to study the effect of increasing the number of feeding places per pen on performance, behavior, and welfare indicators during the 4 wk after arrival. Treatments consisted of 1 (T1), 2 (T2), or 4 (T4) concentrate feeding places/pen (8 calves/pen). Concentrate and straw were fed at 0830 in individual feeders, and animals were allowed to consume on an ad libitum basis. Dry matter intake and ADG were recorded weekly, and blood samples were taken on d 0 (before transport), 7, 14, 21, and 28. Time spent in maintenance activities, number of displacements between calves, and the angular dominance value (ADV) were registered at wk 1 and 3 after arrival. Increasing the number of feeding places per pen resulted in a quadratic response of concentrate and total DMI, ADG, and BW during the 28-d period, with T1 showing the lowest values. Straw intake and the within-pen SD of ADG tended to decrease linearly (P = 0.10) as the number of feeding places per pen increased. During the 4-wk receiving period, and particularly on d 7 after arrival, serum NEFA responded quadratically, with T1 and T2 calves showing the greatest values. With increasing number of concentrate feeders, the average time spent lying increased (P = 0.001), standing time decreased linearly (P = 0.001), and the diurnal feeding pattern changed (concentrate eating time increased but straw eating time decreased during peak feeding times, P < 0.05). The number of displacements from the concentrate feeders responded quadratically (P < 0.001) with increasing number of feeding places per pen, with T4 calves showing the lowest levels of aggression. In T1 calves, increasing ADV resulted in a linear decrease (P = 0.03) of ADG at wk 1 with a quadratic effect at wk 3 (P < 0.01). In T2 calves, increasing ADV resulted in a linear decrease (P = 0.04) of ADG at wk 1 but a linear increase (P = 0.02) at wk 3. No effect of social rank on ADG was observed in T4 calves (P > 0.20). Increasing social pressure at the concentrate feeders beyond the threshold of 4 heifers per feeder had a negative effect on performance. Within-pen variability in performance increased linearly as a consequence of greater effects of social dominance. Physiological indicators of welfare were not consistently affected by treatments.

Selection of a novel direct-fed microbial to enhance weight gain in intensively reared calves

A novel bacterial strain isolated in Australia, Propionibacterium jensenii 702 (PJ702), was examined for its potential as a direct-fed microbial to improve weight gain in calves. Holstein bull calves, 24, were randomly allocated into a Treatment or Control group and held under simulated commercial calf rearing conditions. Both groups were treated identically, with the exception that the Treatment calves were given between 1.1×10 8 and 1.2×10 9 cfu/(kg day) of PJ702. Faecal recovery of PJ702 from the Treatment calves from week 2 indicated successful gastrointestinal transit of the bacterium, and blood haematology and biochemistry indicated no adverse effects following PJ702 administration. There were improvements in weight gains with the Treatment group during both the pre-weaning (P=0.001) and the weaning period (P=0.04). Eighteen weeks after cessation of treatment, and removal to an extensive farming operation, Treatment calves remained heavier to the Control calves (P=0.03), with a final weight difference between the groups of 21.3 kg.

Temperature dependence of collagen fluorescence

Dermal collagens have several fluorescent moieties in the UV and visible spectral regions that may serve as molecular probes of collagen. We studied the temperature-dependence of a commercial calf skin collagen and acid-extracted Skh-1 hairless mouse collagen at temperatures from 9 degrees C to 60 degrees C for excitation/emission wavelengths 270/305 nm (tyrosine), 270/360 nm (excimer-like aggregated species), 325/400 nm (dityrosine) and 370/450 nm (glycation adduct). L-tyrosine (1 x 10(-5) M in 0.5 M HOAc) acted as a "reference compound" devoid of any collagen structural effects. In general, the fluorescence efficiency of these fluorophores decreases with increasing temperature. Assuming that rate constant for fluorescence deactivation has the form k(d)(T) = k(d) degrees exp (-DeltaE/RT), an Arrhenius plot of log[(1/Phi) - 1] vs. 1/T affords a straight line whose (negative) slope is proportional to the activation energy, DeltaE, of the radiationless process(es) that compete with fluorescence. Because it is difficult to accurately measure Phi(f) for collagen-bound fluorophores, we derived an approximate formula for an activation parameter, DeltaE*, evaluated from an Arrhenius-like plot of log 1/I(N)vs. 1/T, (1/I(N)vs. is the reciprocal normalized fluorescence intensity). Tyrosine in dilute solution affords a linear Arrhenius plot in both of the above cases. Using the known value of Phi(f) = 0.21 for free tyrosine at room temperature, we determined that DeltaE* is accurate to approximately 25% in the present instance. Collagen curves are non-linear, but they are quasi-linear below approximately 20 degrees C, where the helical form predominates. Values of DeltaE* determined from the data at T < 20 degrees C ranged from 6.2-8.4 kJ mol(-1) (1.5-2.0 kcal mol(-1)) for mouse collagen and 10.3-11.4 kJ mol(-1) (2.5-2.7 kcal mol(-1)) for calf skin collagen, consistent with collisional deactivation of the fluorescent state via thermally enhanced molecular vibrations and rotations. Above 20 degrees C, log 1/I(N)vs. 1/T plots from Skh-1 hairless mouse collagen are concave-downward, suggesting that fluorescence deactivation from the denatured coil has a significant temperature-independent component. For calf skin collagen, these plots are concave-upward, suggesting an increase in activation energy above Tm. These results suggest that collagen backbone and supramolecular structure can influence the temperature dependence of the bound fluorophores, indicating the future possibility of using activation data as a probe of supramolecular structure and conformation.

Effects of Additional Milk Replacer Feeding on Calf Health, Growth, and Selected Blood Metabolites in Calves

The objective of the experiment was to evaluate effects of increased milk replacer feeding on growth, intake, feed efficiency, and health parameters in stressed calves. Holstein bull calves (n = 120; approximately 3 to 8 d of age) were purchased from sale barns and dairy farms and housed in fiberglass hutches. In addition, wood shavings contaminated with coronavirus were mixed with clean shavings and added to each hutch before the start of the experiment. Calves were fed either a fixed amount (454 g/d) of a 20% crude protein (CP), 20% fat milk replacer to weaning at 28 d or a variable amount (454, 681, 908, and 454 g/d on d 0 to 7, 8 to 14, 15 to 31, and 32 to 41, respectively) of a milk replacer containing 28% CP and 17% fat without or with added dietary supplement containing bovine serum. Calves were also fed commercial calf starter and water ad libitum. Plasma IgG concentration in most calves on arrival at the facility was<10g/L. Intake, change in body weight, feed efficiency, morbidity and mortality, and selected plasma metabolites were determined. Body weight at 28 d, 56 d, daily body weight gain, intake of milk replacer, fecal scores, days with diarrhea, and days treated with antibiotics were increased with feeding variable amount of milk replacer over the 56-d study. Starter intake from d 1 to 56 was reduced from 919 to 717 g/d in calves fed fixed and variable amounts of milk replacer, respectively. Morbidity, measured as the number of days that calves had diarrhea, was increased by 53% when a variable amount of milk replacer was fed. Calves fed variable milk replacer were treated with antibiotics for 3.1 d compared with 1.9 d for calves fed 454g of milk replacer/d. Concentrations of plasma glucose, urea N, and insulin-like growth factor-I were increased when calves were fed variable amount of milk replacer. Dietary supplement containing bovine serum had no effect on any parameter measured. There was no effect of milk replacer feeding on concentrations of nonesterified fatty acids, total protein, or growth hormone concentrations. Plasma tumor necrosis factor-α was highest in calves with the highest plasma IgG concentrations on the day of arrival and might be related to the calf's ability to identify pathogens in the environment. Under conditions of this study, calves fed variable amount of milk replacer and exposed to immunological challenge before weaning had greater BW gain, but also increased incidence of diarrhea that required added veterinary treatments.

Effects of Vegetable Fats Versus Lard in Milk Replacers on Feed Intake, Digestibility, and Growth in Finnish Ayrshire Bull Calves

The aim was to study whether vegetable fat mixtures could be used instead of lard [15.2% in dry matter (DM)] in milk replacers without impairing the performance of Finnish Ayrshire bull calves (n=58). The growth performance of the calves was measured before and after weaning from 14 d to 6 mo of age. The following 3 fat sources in a milk replacer were studied: 1) a mixture of palm, coconut, and rapeseed oil, 2) palm and coconut oil, and 3) lard. The calves were bucket-fed 2L of milk replacer 3 times per day. The milk replacer contained 116g of DM/L, resulting in an average DM intake of 4.8g of DM/kg of body weight0.75 (BW0.75) during the 8-wk trial, after which the calves were weaned. All the calves had free access to water, commercial starter, and grass silage before weaning. The weaned calves had free access to water and grass silage and were given 3 kg/d (air-dry basis) of a commercial concentrate mixture. The concentrate was replaced by barley when the bulls were 4.5 mo old. There were no significant differences between the diets in feed intake and apparent diet digestibility. The health and BW of the calves were similar during the study. The feed conversion rate (kg of DM intake/kg of gain) before weaning was significantly greater for the lard diet compared with the 2 vegetable fat mixtures. After weaning, the feed conversion rate was slightly lower for the diet that included the palm, coconut, and rapeseed oil mixture than for the diet that included palm and coconut oil mixture. The study showed that the 2 mixtures consisting solely of vegetable oils were effective dietary components, thus providing 2 alternative fat mixtures of milk replacers, for use instead of lard in formulating commercial calf milk replacers.

Biochemical and microbiological characterization of artisan kid rennet extracts used for Cabrales cheese manufacture

Four samples of artisanal kid rennet extracts from four different Cabrales cheese producers were biochemically and microbiologically characterized. Most samples had a very acidic pH (around pH 4.0), which may condition their biochemical and microbial variables. The milk-clotting activity of the extracts was assessed using a Formagraph apparatus. The properties of these artisanal rennets were found to be comparable to a 1/10 dilution of 1:10,000 commercial calf rennet; their enzymatic potentials, measured with a semi-quantitative commercial system (API ZYM), showed only very slight differences. A large population of lactobacilli was found in all artisanal kid rennet samples, whereas coliforms, enterococci, staphylococci and leuconostocs were only occasionally encountered. Sixty-four representative colonies were classified by PCR amplification and the sequencing of a stretch of their 16S rDNA genes. Strains of Lactobacillus plantarum completely dominated one of the extracts. In all others samples, strains of this homofermentative species and of the heterofermentative Lactobacillus brevis were present in similar amounts.

Formulation and testing of a whey-based kid goat's milk replacer

A milk replacer using 29% whey and vegetable oils was formulated for kid goats in order to reduce costs of kid goat feeding. This new milk replacer (FCA) was compared with a commercial (COM) calf milk replacer, generally used by farmers in the rearing of young goats. Twenty-six Saanen-Criollo kids were fed from 6 to 57 days of age with these two replacers ad libitum. The replacers were given warm (37 °C) and at an approximate concentration of 17% DM. Differences of growth were found between treatments ( P < 0.05), being the daily gain average 120.6 and 132.3 g/day for FCA and COM, respectively. The DM conversion index was 1.4 kg DM replacer/kg weight gain in FCA treatment and 1.64 in COM. The total costs of the milk replacers were 12.22 and 31.11 US$ per animal for FCA and COM, respectively. Muscular and perirenal fat contents were higher in FCA goats. Fatty acid composition of perirenal fat showed differences in 9 fatty acids; in the case of FCA, 1.48:1 ratio of Omega 6:Omega 3, less than 7.19:1 of COM; and unsaturated/saturated ratio of 1.22 in FCA, more than 0.92 in COM. The ratios are more beneficial for human nutrition in kid goats fed FCA replacer. A meat acceptability trial was done, and no differences were found between treatments ( P > 0.05). It can be concluded that in spite of the lower intake and growth obtained with FCA, its better DM conversion index and lower cost, make its use economically feasible, besides, that carcass more suitable for consumers was obtained.

Influence of serum source on buffalo in vitro embryonic development with reference to heat inactivation

The present study was conducted to evaluate the effect of serum source either prepared or commercial, and the effect of serum heat inactivation on cleavage rate and subsequent embryo development in buffalo. Ovaries were collected from slaughtered buffaloes. The follicular contents were collected from 2 to 5 mm diameter ovarian follicles by aspiration. The recovered oocytes with at least two layers of compact cumulus cells and homogenous cytoplasm were selected. Oocytes were matured in vitro using TCM-199 supplemented with four types of 10% sera: heated commercial calf serum, unheated commercial calf serum, heated prepared buffalo calf serum and unheated prepared buffalo calf serum with antibiotics for 24–25 h at 38.5 °C in an atmosphere containing 5% CO 2 in air and 95% relative humidity. The in vitro matured oocytes were co-cultured with spermatozoa capacitated in Brackett and Oliphant medium containing caffeine and heparin for 4 h. Then they were cultured in TCM-199 with each of the four types of previous sera for embryo development. The rate of cleavage, morula and blastocyst was assessed after 3, 5 and 7 days of insemination. The results showed that there were no significant differences in cleavage, morula and blastocyst rates between the use of commercial calf serum and prepared buffalo calf serum either heated or unheated. It could be concluded that prepared buffalo calf serum can be used instead of imported calf serum to evolve the cost of protein supplement in buffalo IVF. Moreover, the serum inactivation by heat treatment seems to be unnecessary.

Novel Approach for Food Safety Evaluation. Results of a Pilot Experiment To Evaluate Organic and Conventional Foods

There is evidence that organic food often contains relatively high amounts of natural toxic compounds produced by fungi or plants, whereas corresponding conventional food tends to contain more synthetic toxins such as pesticide residues, but only a few studies have evaluated the impact of their consumption on health. This study proposes a novel approach to evaluate the potential health risk of organic compared to conventional food consumption, that is, the assay of sensitive markers of cell function in vulnerable conditions. The markers utilized were intestinal and splenic lymphocyte proliferative capacity and liver acute-phase reaction, both responding to the presence of toxins. The vulnerable conditions in which body defenses can be less efficient were weaning and protein-energy malnutrition. This study reports the results of a pilot experiment on one sample of eight varieties of organically and conventionally grown wheat. Weaned rats were assigned to two groups fed conventional (CV) or organic (ORG) wheat for 30 days. Each group was divided in two subgroups of well-nourished (WN) or protein-energy-malnourished (PEM) rats. For each rat, the lymphocyte proliferation was assayed by [(3)H]thymidine incorporation after stimulation of cells with a mitogen, in a culture medium containing either commercial fetal calf serum (FCS) or the corresponding rat serum (RS) to mimic the in vivo proliferative response. The acute-phase proteins (albumin, transthyretin, transferrin, ceruloplasmin, retinol-binding protein) were measured in plasma by Western blotting and immunostaining with specific antibodies. The proliferative response of lymphocytes cultured with FCS and the amount of acute-phase proteins of rats fed the ORG wheat sample, either WN or PEM, did not differ from those of rats fed the CV wheat sample. However, the proliferative response of lymphocytes cultured with RS was inhibited in PEM-CV compared with PEM-ORG. The content of mycotoxins was highest in the organic sample, and therefore the immunotoxic effect was probably due to other contaminants in the CV wheat. In conclusion, these results indicate that the conventional wheat sample tested represented a higher risk for lymphocyte function than the wheat sample organically grown, at least in vulnerable conditions.

Case report

In the fall of 2001, a large commercial dairy calf and heifer raising operation in New York, USA, suffered an outbreak of acute neonatal diarrhoea. Prior to the outbreak, mortality before weaning was 2.5%, and during the outbreak preweaning mortality reached 10%. Multidrug-resistant Salmonella spp. serogroup C2 (serotype Newport) was recovered from clinically affected calves as well as from many environmental sites, including footbaths. This paper identifies some risk factors, such as low serum total protein, and reviews management protocols that were helpful, as well as those that were not (e.g., footbaths), for controlling transmission of Salmonella spp.

Babesia divergens (Phylum Apicomplexa) in vitro growth in the presence of calf serum

Resistance to severe babesiosis in young calves has frequently been ascribed to an unknown serum factor(s) which inhibits growth of Babesia bovis in vitro. Our experiments show that young calf sera are as suitable as adult bovine sera for the in vitro culture of Babesia divergens, indicating that in this species at least inverse age resistance is due to alternative mechanisms. The suitability of commercial foetal calf sera for B. divergens cultures seems highly variable.

Babesia divergens (Phylum Apicomplexa) in vitro growth in the presence of calf serum

Resistance to severe babesiosis in young calves has frequently been ascribed to an unknown serum factor(s) which inhibits growth of Babesia bovis in vitro. Our experiments show that young calf sera are as suitable as adult bovine sera for the in vitro culture of Babesia divergens , indicating that in this species at least inverse age resistance is due to alternative mechanisms. The suitability of commercial foetal calf sera for B. divergens cultures seems highly variable.

Effect of artisanal liquid rennet from kids and lambs abomasa on the characteristics of Feta cheese

Feta cheeses were manufactured with commercial calf rennet and artisanal liquid rennet from kids and lambs abomasa with an aim to investigate the influence of rennet type on the characteristics of this cheese variety. The two rennets had similar chymosin to pepsin ratios and they were used in quantities with the same total milk coagulating activity. The use of traditional rennet had no significant effect on the evolution of physicochemical composition (pH, total solids, ash, NaCl, fat, total protein) or on the evolution of proteolysis (water-soluble nitrogen expressed as percentage of total nitrogen, free amino acids expressed as mmol Leu, residual α s-casein and reversed phase HPLC profiles) during the ripening. The textural characteristics of mature 60d-old cheeses were not significantly different. The microbiological quality of traditional rennet significantly affected the enterococci and coliform counts of 3d-old cheeses but this influence was eliminated in the mature 60d-old cheeses. The significantly higher flavour scores of mature Feta made with traditional artisanal liquid rennet were in accordance with the significantly higher C4:0 and C10:0 FFA contents resulting from the lipase activity of traditional rennet.

Effect of ripening time and type of rennet (farmhouse rennet from kid or commercial calf) on proteolysis during the ripening of León cow milk cheese

Classical nitrogen fractions, caseins and their degradation products, and free amino acids were determined during ripening of six batches of León raw cow milk cheese. Three batches were made using commercial calf rennet (average 1/8342 strength and 76% of chymosin) and three were made using farmhouse rennet obtained from kid abomasum (average 1/857 strength and 34% of chymosin). The pH 4.6-soluble nitrogen and the 12% TCA-soluble nitrogen contents increased moderately during ripening, reaching significantly ( P<0.05) higher average final values in the cheeses made using commercial rennet (18.0 and 11.0% of TN, respectively) than in the cheeses made using farmhouse rennet (8.3 and 5.1% of TN, respectively). The greater extent and intensity of proteolysis registered in the cheeses made using commercial rennet, especially after 15 days of ripening, became clear again on quantifying the caseins and their degradation products. β-Casein did not undergo any appreciable degradation during ripening. In the cheeses made using commercial rennet, 20% of the αs-caseins were degraded during ripening, whilst in those made using farmhouse rennet only 10% of the αs-caseins were degraded. These results show that this cheese undergoes a slight proteolysis and that the rennet plays a preponderant role in protein degradation. The content of total free amino acids increases progressively during ripening. In the batches made using commercial rennet, the final values were double those found in the batches made using farmhouse rennet. In the mature cheeses, the major free amino acid was lysine, followed by leucine, glutamic acid, tryptophan, valine, and phenylalanine. The type of rennet used during manufacture made no difference to the free amino acid profile at maturity.

Use of Australian cardoon extract in the manufacture of ovine milk cheese – a comparison with commercial rennet preparations

SummaryAqueous extract of Australian cardoon (Cynara cardunculus L.) flowers was used to produce Pecorino cheese from ovine milk and the chemical, biochemical and sensory properties of the cheese were compared with cheeses made using two commercial (calf and microbial) rennet preparations. The cheeses contained 49.8–54.6% moisture, 28.2–31.2% fat, 2.1–2.3% NaCl and 2.6–3.1% total nitrogen. Very few differences in chemical composition were observed between cheeses manufactured with the three different coagulants. Biochemically, however, cheese manufactured with cardoon extract contained significantly (P &lt; 0.05) higher levels of water‐soluble nitrogen but lower levels of phosphotungstic acid soluble nitrogen, while the levels of trichloroacetic acid soluble nitrogen were similar among the three types of cheese. Compared with cheeses made with commercial rennet preparations, cheese made with cardoon extract was perceived to be softer, creamier and less bitter, and was rated significantly (P &lt; 0.05) higher in overall liking by both trained and consumer panels.

Proteolytic and milk clotting activities in extracts obtained from the crustaceans Munida

In the present study, individuals of the crustaceans Munida have been investigated as a possible source of enzymes to be used in cheese making as an alternative to calf rennet. The crustaceans were blended and the extracts were filtered and tested for their proteolytic activity and milk clotting capability. The optimal values of pH and temperature of the total proteolytic activity determined on azocasein were in the ranges pH 6.5–7.5 and 55–60 °C, respectively. The extracts showed a higher capability to cleave α S1-casein than β- and k-casein. As determined with specific inhibitors, using azocasein or zymography, the extracts appeared to contain serine proteases as well as cysteine and aspartic proteases. Hydrolysis of β-casein gave peptides which were different from those obtained with trypsin or a commercial calf rennet. Moderate milk clotting activity was also present. The ability to cleave casein, in particular α S1-casein, and the moderate clotting activity, indicate that the extracts of the crustaceans Munida could be useful in the dairy industry both for milk clotting, as an alternative or in addition to calf rennet, and for the acceleration of cheese ripening in order to reduce time and costs of storage and maturation of cheese.

Effects of Spray-Dried Animal Plasma in Calf Milk Replacer on Health and Growth of Dairy Calves

Male Holstein calves (n=120) purchased from local dairy farms were fed one of three calf milk replacers for 42 d. Experimental milk replacers were formulated to contain whey protein concentrate (WPC) as the primary protein source or WPC plus 5% spray-dried bovine plasma (SDBP) or spray-dried porcine plasma (SDPP). The SDPP was heated to remove heat-insoluble materials and provide products with similar IgG content. Calves were also fed commercial calf starter and water for ad libitum consumption. Intake, change in body weight (BW), feed efficiency, morbidity and mortality were determined. Mortality was 10, 3, and 2 in calves fed WPC, SDBP, and SDPP treatments, respectively. Morbidity, measured as the number of days that calves had diarrhea was reduced by 30% when SDBP or SDPP were fed. Calves had diarrhea for 6.9, 3.9, and 4.7 d during the 42-d study when fed commercial calf milk replacer containing WPC, SDBP, and SDPP, respectively. Fecal scores tended to be reduced and feed efficiency tended to be improved when SDBP or SDPP were fed. Mean intakes of total dry matter during the 42-d study were greater when calves were fed SDBP or SDPP and were 661, 710, and 684 g/d for calves fed WPC, SDBP, and SDPP, respectively. Mean BW gains from d 0 to 42 were 231, 261, and 218 g/d, respectively. Calves fed SDPP tended to have lower BW gain during the first 28 d of the study. However, difference in daily BW gain from d 1 to 28 was only 39 g/d. Inclusion of SDBP or SDPP in milk replacer reduced morbidity and mortality of milk-fed dairy calves.

Triple synchronisation of suckler cows

TRADITIONALLY, suckler herds have depended almost entirely on natural service, with artificial insemination only being used on small numbers of cows in a few pedigree herds. However, over the past...

Development of an on-line liquid chromatography-electrospray tandem mass spectrometry assay to quantitatively determine 1,N(2)-etheno-2'-deoxyguanosine in DNA.

A method involving on-line reversed-phase high-performance liquid chromatography with electrospray tandem mass spectrometry detection has been developed for the analysis of 1,N(2)-etheno-2'-deoxyguanosine in DNA. This methodology permits direct quantification of 20 fmol (7.4 adducts/10(8) dGuo) of the etheno adduct from approximately 350 microg of crude DNA hydrolysate. Using the newly developed technique, basal levels of 1,N(2)-etheno-2'-deoxyguanosine were determined in commercial calf thymus DNA (1.70 +/- 0.09 adducts/10(7) dGuo), in cultured mammalian cells (CV1-P) DNA (4.5 +/- 0.4 adducts/10(7) dGuo), and in untreated female rat liver DNA (5.22 +/- 1.37 adduct/10(7) dGuo). The mutagenicity of 1,N(2)-etheno-2'-deoxyguanosine had already been demonstrated by in vitro and in vivo systems. The method described here provides the first evidence of the occurrence of 1,N(2)-etheno-2'-deoxyguanosine as a basal endogenous lesion and may be usefully employed to assess the biological consequences of etheno DNA damage under normal and pathological conditions.