Changes in metabolites and metabolic hormones during the first 12 weeks postpartum in both summer and winter were analyzed on a total of 18 lactating, Holstein cows (summer, n=11; winter, n=7). The summer trial covered the months of August through October. The winter trial began in November and lasted through early February. Maximum and minimum temperature and humidity values were recorded daily. Blood was sampled in serum, fluoride and heparin tubes from the coccygeal vein once a week beginning at day of calving for 12 weeks. Concentrations of progesterone, cortisol, thyroxine, leptin, NEFA, cholesterol and insulin were analyzed from serum samples. The metabolites glucose, PUN and â-HBA were analyzed with plasma collected from fluoride and heparin containing tubes. No significant seasonal differences were found between summer and winter calving groups for P4, T4, glucose, insulin, PUN and NEFA. However, leptin (P < 0.01), cholesterol (CHL) (P < 0.0001) and â-HBA (P < 0.0001) had significant seasonal differences between the two calving groups. The mild heat stress during the early part of the summer trial may not have been severe enough to detect significant changes in serum T4 or the animals had become acclimated to these temperatures. Summer calving cows may have experienced a drop in feed intake at calving (not measured) enough to increase their plasma ketone bodies (â-HBA), but not enough to dramatically reduce circulating levels of glucose and insulin.

The objective of this study was to characterize follistatin (FOL) as a candidate gene for litter size in pigs. Litter size is a lowly heritable and sex-limited trait; therefore, response to selection may be enhanced by marker-assisted selection. Our approach for characterizing a region of SSC16, which includes FOL, was to utilize the candidate gene approach using type I and type II markers to determine if FOL had an association with the response to selection for increased litter size in the select line. Pigs genotyped were from a line selected for increased number of fully formed (FF) pigs and a contemporary control line. In generation nine, the estimated breeding value for litter size was 0.63 pigs greater in the select line than in the control line (Holl et al., 2003). A RFLP within FOL (n = 251) and the microsatellites, CGT27 (n = 224), S0363 (n=255), S0298 (n=260), and SW1661 (n=253) were genotyped. Effect of marker genotype on FF, number born alive (BA), number still born (SB), and number mummified fetuses (MUM) was tested. Data were analyzed by line with an animal model using MTDFREML. Fixed effects included year and marker genotype. In both the select and control lines, all markers had no significant affect on FF, BA, SB, or MUM when using the animal model. Therefore, follistatin is not likely to have a major effect on litter size in the population studied.

Continued genetic improvement for milk production has been associated with decreased fertility in US Holstein cattle. A previous study (Ashwell et al., 2004) identified a putative quantitative trait locus (QTL) affecting daughter pregnancy rate at 54 cM on chromosome 18 in one Holstein grandsire family. The goal of this research is to determine the validity of the putative QTL using additional markers and an extended pedigree. Thirteen microsatellite markers located throughout the chromosome were genotyped in 973 animals that were descendants of the original grandsire in which the QTL was identified. Sons of the grandsire as well as six grandson and six great-grandson families of the original grandsire were selected for this study (range of 16 to 169 sons per family). In analysis of the sons using QTL Express, the same putative QTL affecting daughter pregnancy rate was detected and placed at 45 cM. In a joint analysis of thirteen of the largest families, each containing 10 or more sons, a significant QTL for daughter pregnancy rate was detected at 27 cM. QTL affecting daughter pregnancy rate was detected in two additional sub-families (Family II-5 and Family III-2), indicating a putative QTL affecting daughter pregnancy rate is most likely segregating within this pedigree. Across-family analysis also detected putative QTL on chromosome 18 affecting productive life at 35 cM, somatic cell score at 33 cM and percent difficult births at 72 cM. Analysis of individual families identified eight significant putative QTL and six suggestive putative QTL at the chromosome-wise level affecting somatic cell score, productive life, calving ease, percent difficult births, milk yield, fat yield, protein yield and fat percent. A complex pedigree analysis is underway to make full use of statistical power to refine the QTL region affecting fertility. Further verification of the QTL effects identified in this study will allow identification of positional candidate genes to be applied in marker assisted breeding programs.

Obesity is rapidly becoming a major problem in the United States and throughout the world. Polygenic models of obesity are most similar to human obesity because few humans are genetically obese due to a mutation in a single gene. Numerous studies have selected mice for body size and growth rate as models for selection of agriculturally important species. One series of selection experiments produced lines of mice having differing epididymal fat (EF) masses but similar body weights. These mice may be used as a model for adipose deposition without confounding the effects of body weight. One method of studying these mice is to examine gene expression. Expression of thousands of genes can be investigated at one time using microarrays. We used microarrays and real-time RT-PCR to compare gene expression between the high epididymal (HE) and low fat (LF) lines of mice, which have dissimilar EF mass but similar body weights. Microarray analysis identified 19 genes with differential expression between the HE and LF lines of mice with 5 of these genes differentially expressed in both liver and EF tissues. We found differential regulation of genes known to play a role in glucose uptake and lipid metabolism. In addition, we identified a differentially expressed gene, <I>solute carrier family 22 member 4</I>, located within the confidence interval of a quantitative trait loci associated with EF mass, making it a positional candidate. Furthermore, we identified a linked group of three genes (<I>Sortilin 1</I>, <I>guanine nucleotide binding protein alpha inhibiting 3</I>, and <I>selenium-binding protein 2</I>) on <I>Mus musculus</I> chromosome 3 (MMU3), which may represent a genomic ?hot spot? for genes associated with EF mass. In this study, differential expression of several genes not previously associated with obesity or adipose deposition were identified and may represent new targets for further research. Another aspect of obesity currently being investigated is anti-obesity compounds. One such compound is <I>trans</I>-10, <I>cis</I>-12-conjugated linoleic acid (CLA). CLA has been reported to reduce body weight and adipose mass in many species. Numerous studies have reported an increase in size, cytoplasmic vacuolization, and fatty acid synthesis in liver of CLA fed mice. The livers of CLA fed mice gain mass due to lipid accumulation; however, the precise molecular mechanisms are unknown. To elucidate these mechanisms, we examined the fatty acid composition, histology, and gene expression profile of liver from a polygenic obese line of mice fed CLA. Using a Periodic acid-Schiff stain, histological evidence suggests that glycogen content is unchanged in the liver of the CLA fed mouse implying that hepatic cytoplasmic vacuolization is due to increased lipid content. Microarray analysis identified 1393 genes differentially expressed at a nominal P-value of 0.01. Following Bonferroni correction and excluding lowly expressed transcripts, 198 genes were identified as being differentially expressed with 17 genes having ≥2 fold change. Real-time RT-PCR showed up regulation of <I>acylglycerol-3-phosphate O-acyltransferase 2</I> and <I>diacylglycerol O-acyltransferase 2</I> in CLA fed mice, both necessary for triglyceride biosynthesis. Expression of <I>B-cell leukemia/lymphoma 6</I>, a nuclear transcriptional repressor, and <I>signal transducer and activator of transcription 5B</I>, a transcription factor, were shown to be greater in the liver of CLA fed mice. Both genes are associated with immunoregulation. Comparing real-time RT-PCR to microarray data suggest a Bonferroni correction to microarray data is necessary in order to eliminate false positive data. Further verification of microarray results is needed to validate microarray data after a Bonferroni correction.

The purpose of this research was to evaluate line and sex differences in swine feeding behavior traits. Barrows and gilts used in the study were from three sire lines and two dam lines. Data were provided by PIC in Franklin, KY. Feeding behavior traits considered were average daily feed intake (ADFI), average occupation time/day (AOTD), average feed intake/visit (AFIV), average number of visits/day (ANVD), average feeding rate/visit (AFRV), average occupation time/visit (AOTV), and residual average daily feed intake (RADFI). Electronic feeders were used to measure feeding behavior traits on two pens per feeder. Use of the feeder alternated between the two pens weekly. Feeding behavior traits differed by line and sex. Production traits that were used in the study included: average daily gain (ADG), feed conversion ratio (FCR), backfat (BF), loin depth (LD), percent lean (% LEAN), and average daily feed intake (ADFI). For this study, ADFI was treated as both a feeding behavior and performance trait. Feeding behavior traits were used to calculate principal components. Principal components were then treated as traits in terms of statistical analysis.

Infant formula companies began fortifying formulas with long-chain polyunsaturated fatty acids (PUFA) in 2002, including arachidonic acid (AA) at ~ 0.5% of total fatty acids. This study is the first in a series that will examine effects of supra-physiological supplementation of AA on intestinal health. The objective was to determine the time specific effects of dietary AA on fatty acid composition of enterocyte phospholipids and on the mRNA abundance of hepatic ∆6- and ∆5-desaturases. One d old pigs (N=96) were fed a milk-based formula for 4, 8, or 16 d. Diets contained either no PUFA (0%AA, negative control), 0.5%AA, 2.5%AA, 5%AA, or 5% eicosapentaenoic acid (EPA) of total fatty acids. Growth (299 +/- 21 g/d) was unaffected by treatment (P>0.1). By day 16, ileal enterocyte phospholipid concentrations of AA were enriched 176%, 280%, and 355% in pigs fed the 0.5%AA, 2.5%AA, and 5%AA diets, respectively, compared with the 0%AA control (P<0.05). Concentration of AA within enterocytes of the 5% EPA fed group was similar to that of the 0%AA fed pigs, while EPA concentration increased by >8 fold. As pigs aged from birth to 16 d of age, there were no differences in the desaturase mRNA abundance (P>0.1), measured in pigs fed 0.5% or 5%AA. Abundance also was similar among AA-supplemented pigs, but was elevated by 60-80% in the 0%AA-fed pigs compared to those fed 2.5% (P<0.05). These data demonstrate a dose-dependent response in enterocyte AA concentration to dietary AA and show that supra-physiologic supplementation of AA is not detrimental to growth or desaturase gene expression.

The objective of this study was to assess the effectiveness of a Nycodenz gradient enrichment method to enrich a dissociated single cell suspension of porcine testicular cells for spermatogonia, and to observe the separated fractions from the gradient over a 14-day culture period for cell viability and number of spermatogonia in culture. Two germ cell specific genes, VASA and DAZL, were utilized for detection of spermatogonia using immunohistochemistry. The control group included cultures generated from the enzymatic digestion of porcine testes prior to the enrichment protocol for each replicate. The NycoDenz gradient consistently separated the isolated cell suspension into three distinct layers and a pellet, all of which were assessed for spermatogonial enrichment. Testis cells were isolated and seeded in culture on day 0. Cell viability and percent of spermatogonia was assessed on day 0, 7, and 14 of culture. Viability was determined using trypan blue exclusion assay and quantified using a hemocytometer. Spermatogonia were morphologically identified as round, plump cells with a large amount of cytoplasm. Visualization of spermatogonia was facilitated by immunostaining with DAZL and VASA polyclonal antibodies and cells exhibiting morphological characteristics in addition to bright, concentrated fluorescence were counted as spermatogonia.

A major factor in maximizing microbial protein synthesis is the availability of energy and protein in the diet. Our objective was to determine the effect of fermentable carbohydrate and protein on microbial fermentation. Diets were formulated using three ingredients, soybean meal (SBM), ground corn (GC) and soybean hulls (SBH). Corn and SBH were used in ratios of 60:20, 40:40 or 20:60, respectively to prepare high, medium or low non-fibrous carbohydrate (NFC) diets. Soybean meal was included either unextruded (control) or extruded at low, medium or high temperature. Degradability of the N fractions in the control, low, medium and high soybean meal were 97, 80, 80 and 60%, respectively. Diets were arranged as a 3 x 4 factorial (3 levels of corn/soybean hulls and 4 levels of protein) and analyzed as a completely randomized block design. There were no statistically significant interactions seen between NFC and protein sources. Total volatile fatty acids were affected (P<0.01) by the NFC with 78.5, 63.2 and 71.5 mM with increasing NFC levels. The NFC level affected the acetate and butyrate whereas the protein source had an effect on the propionate. Molar ratios of acetate, propionate and butyrate averaged 60.1, 31.0 and 6.79, respectively. Varying the level of fermentable carbohydrate had a negative linear affect on ruminal pH (P<0.01). Extrusion did not alter pH greatly P>0.67). Higher extrusion temperatures altered ammonia concentrations when compared to control or low extrusion. In the low NFC diets, the medium and high extrusion increased (P<0.10) ammonia concentration (29.8 and 32.6 mg/dl, respectively) when compared with control and the low (18.9 and 23.4 mg/dl, respectively). Methane concentration averaged 308 nmoles/ml and was affected by both the NFC treatment and protein source. The high and medium NFC diets increased (P<0.01) bacterial nitrogen percentage (9.0 and 9.5%, respectively) compared to the low NFC diet (8.7%). Data suggest that the fermentability of the structural carbohydrates in SBH was similar to the high starch corn diets. Furthermore, large differences in protein degradability did not seem to have a major impact on microbial fermentation.

<p>Today, dairy farmers in the U.S. are faced with the challenge of reducing the cost of producing milk. Milk prices have risen very little in the past decade, while the cost of producing milk has risen steadily. In North Carolina alone, dairy farm numbers have dropped more than 30% in the last ten years, and the trend is expected to continue. Dairy farmers have been forced to increase their profitability to stay in business. In addition, farmers have been forced to comply with stricter environmental regulations. Over the past few years, interest has been shown in intensive management rotational grazing systems. This four-year comparison trial was designed to compare the milk production, herd health, reproductive performance, and environmental impacts of pasture-based and confinement feeding systems using Holstein and Jersey cattle for the Mid-Atlantic region. The project had both Spring and Fall calving herds with breeding via artificial insemination in 75-day periods. Each seasonal herd replicate had 36 cows on pasture and 36 cows in the confinement group. Similar numbers of Holsteins and Jerseys were included in each year. Paddocks grazed comprised 29 ha of cool and warm season pasture species in 37 paddocks for year-round grazing. Pasture-fed cows received variable amounts of grain and baled silage as needed depending upon pasture availability. Confinement cows were housed in a covered freestall barn with access to an exercise lot and received a total mixed ration with corn silage as the primary forage. Confinement cows produced significantly more milk than pasture-fed cows, both for total lactation and average daily production. Reproductive performance of the two treatments did not differ with an overall 75-day pregnancy rate of 68%. Jerseys in both systems did have higher percentages of cows inseminated (96.5%), conception rate (59.6%), and 75-day pregnancy rate (78%) compared to Holsteins (86%, 49%, 57.9% respectively). The percentage of cows infected with at least one case of clinical mastitis was higher in the confinement herd than the pasture-fed herd (43% vs. 24%) with Holsteins higher than Jerseys (41% vs. 26%). Interactions of breed and feeding system and average somatic cell count scores were not significantly different. Pasture-fed cows had lower average body condition scores than confinement cows, ranging from 0.2 to 0.6 points lower on a 5-point scale.In a short-term trial, intake measurements were taken from pasture-fed Holsteins and Jerseys consuming a grain supplement. This supplement was similar to those that were fed to the pasture-fed cows during the four-year trial. It was determined that Jerseys could consume as much as Holsteins at three different feeding levels (6.8, 4.5, and 2.3 kg/cow per feeding). This experiment showed that in certain time frames, Jersey cattle can consume equal amounts of supplements compared to Holsteins. Therefore in mixed groups Jerseys can consume relatively more supplemental energy relative to body size and milk production compared the Holsteins. In another short-term trial using cows from a spring season replicate, milk samples were obtained from pasture-fed and confinement-fed cattle and analyzed for fatty acid composition. The pasture grazed was a warm-season pasture, while the confinement-fed cattle consumed a corn-silage based TMR. The major fatty acid of interest was conjugated linoleic acid (CLA), which has been shown to be a potent anticarcinogen. Concentrations of CLA were 80% higher in pasture-fed cattle compared to the confinement-fed cattle. In addition concentrations of CLA were higher in Holsteins compared to Jerseys. To study the distribution of manure in a pasture-based system, pastured cows were observed for several 24-h periods. Data included: (1) times and location of all feces and urine events from eight cows, observed while in the pasture, feed area, milking parlor or in transit; and (2) all urine and feces events on pasture for all 36 cows each grazing period. The locations of urine and feces events were surveyed, mapped and analyzed. Percentages of the manure events in each area were highly correlated with time spent in each area (r= .99). Feces and urine (estimated at .12 m2 and .36 m2, respectively) from six observational periods covered 10% of the total paddock. Within 30 m2 of the portable waterer and gate, concentrations of feces and urine from the warm season observations were significantly greater than concentrations during the cool season observations. Manure on pasture was relatively evenly distributed over multiple grazing periods with the exception of the area around the water tank during summer grazings. These experiments showed that when compared to confinement-fed cattle, pasture-fed cattle produced less milk, produced more conjugated linoleic acid, had less mastitis and had lower body condition scores, while reproductive performance did not differ between the two groups. Jerseys had less mastitis, produced less conjugated linoleic acid, and performed better reproductively when compared to Holstein cattle. In addition, pasture-fed Jersey cattle can consume as much supplemental grain in certain time frames as pasture-fed Holstein cattle. Manure distribution on a pasture-based system is highly correlated with time spent in an area and is fairly evenly distributed over the paddock area over multiple grazing periods except for the area around the water tank during heat stress temperatures.<P>

<p>A series of experiments was conducted to examine the absorption and post-absorptive metabolism of zinc (Zn) from inorganic and organic sources. Results of an in vivo experiment, using Holstein bull calves as models, suggested that, when Zn was supplemented at 20 mg Zn/kg DM for 98 d, Zn source had minimal impact on plasma or tissue Zn concentrations. However, when Zn was supplemented at 500 mg Zn/kg DM for 12 d, plasma and tissue Zn concentrations were greater in bulls that received Zn proteinate (ZnProt) than in those that received ZnSO and Ca only, uptake and transport of Zn from inorganic and organic Zn sources were similar. However, when added at high concentration in the presence of dietary antagonists, Zn uptake from organic sources appeared to be greater than from inorganic sources. Further research is certainly warranted to more clearly define differences in Zn absorption that may exist between inorganic and organic Zn sources at different dietary levels.<P>