Effects of pre‐partum milking of dairy cows on calcium metabolism at start of milking and at calving

This experiment studied the effect of pre‐partal milk removal on calcium metabolism at start of milking and at calving. Nine cows of the Swedish Red breed were milked for 1–7 days pre‐partum. The average milk yield at the first milking was 4.8 l, and the average yield the last day prior to calving was 13.4 l. Five cows were used as control cows and were only milked post‐partum. Samples of plasma and urine were taken to determine the effect of pre‐partum milking and calving on levels of calcium, magnesium, parathyroid hormone and plasma C‐terminal crosslinked telopeptide of type 1‐collagen (CTx), used as a marker of bone resorption. Pre‐partum milking resulted in a decrease in plasma calcium that was evident 2 days after the first milking. Parathyroid hormone increased at the same time, and CTx started to increase from 24 h after the first milking. There were no effects on plasma magnesium or urinary output of calcium or magnesium. The first week after calving, there were no differences between pre‐partum milked cows and control cows in plasma or urine variables, or in milk yield. In conclusion, pre‐partum milking activated the calcium‐restoring mechanisms but did not improve calcium status at calving.     

Buffer nitrogen solubility,in vitro ruminal partitioning of nitrogen and in vitro ruminal biological activity of tannins in leaves of four fodder tree species

This study explores the chemical composition, buffer N solubility, in vitro ruminal N degradability and in vitro ruminal biological activity of tannins in leaves from Gliricidia sepium, Leucaena leucocephala, Morus alba and Trichanthera gigantea trees. These tree leaves are a potential protein source for ruminants, but their site‐influenced nutritive value is largely unknown. Leucaena leucocephala leaves had the highest N content (42.1 g/kg DM), while T. gigantea leaves had the least (26.1 g/kg DM). Leucaena leucocephala had the highest buffer solubility index (20%), while 10% of the total N in leaves of the other three species was soluble. The rapidly fermentable N fraction ‘a’ was highest in M. alba leaves (734.9 g/kg DM) and least in T. gigantea leaves (139.5 g/kg DM). The rate of fermentation (c) was highest for M. alba (7%/hours) leaves. No significant correlations were recorded between buffer solubility index of N and in vitro ruminal N degradability parameters: a, b, and c. The highest response to tannin inactivation using polyethylene glycol, in terms of percentage increase in 36‐hours cumulative gas production, was recorded in M. alba (39%) and T. gigantea (38%) leaves. It was concluded that buffer solubility of N is not a good indicator of ruminal N degradation in the leaves of these tree species. Leaves of M. alba could be more valuable as a source of rapidly fermentable N when animals are offered low‐protein, high‐fibre diets compared with other tree species evaluated in the current study. However, when feeding M. alba leaves, the role of tannins must be considered because these secondary plant compounds showed significant in vitro ruminal biological activity.     

Histone H4 Modification During Mouse Spermatogenesis

The core histone is composed of four proteins (H2A, H2B, H3 and H4). Investigation of the modification patterns of histones is critical to understanding their roles in biological processes. Although histone modification is observed in multiple cells and tissues, little is known about its function in spermatogenesis. We focused on the modification patterns of histone H4 during murine spermatogenesis. We demonstrated that the individual N-terminal sites of H4 show different modification patterns during the differentiation of male germ cells. The methylation pattern varied depending on the residues that were mono-, di-, or tri-methylated. All the H4 modifications were high during the meiotic prophase, suggesting that histone H4 modification plays an important role during this stage of spermatogenesis. Elongating spermatids showed increased acetylation of histone H4, which may be associated with a histone-to-protamine substitution. Our results provide further insight into the specific relationship between histone H4 modification and gene expression during spermatogenesis, which could help to elucidate the epigenetic disorders underlying male infertility.     

Effects of straw treatment and nitrogen supplementation on digestibility,intake and physiological responses of water intake as well as urine and faecal characteristics

This study investigates the effects of feeding diet based on untreated (UT) or ensiled alkali‐treated (ET) barley straw with either urea or casein supplementation, on feed intake, digestibility, ruminal pH, water intake and faecal and urinary characteristics. Four sheep fitted with ruminal cannulas were used in a 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments. Barley straw was treated by the dry (spraying) method in pH adjusted of hydrogen peroxide (pH 11.5), ensiled for 6 weeks and included at 65% of the diet dry matter (DM). The results showed that straw pH reduced from 11.58 to 8.60 after 6 weeks of ensilage. The ET diet increased average DM digestibility and intake by 19% and 43% respectively. Total water intake was similar across treatments, while the water/DM intake ratio was 23% higher with the UT diet than with the ET one. Ruminal (6.73 vs. 6.84) and faecal (8.67 vs. 9.05) pH decreased but urinary pH (6.14 vs. 8.13) increased as a result of feeding animals on the ET diet compared with the UT diet. Compared with the UT diet, the ET one decreased faecal fibre (12%), moisture (32%) and water holding capacity, while it increased faecal ash (10%) and density (20%). The volume of urine excreted by the sheep fed with the ET diet increased by 67%, but their urine specific gravity (SG) decreased. No significant effects were observed for the dietary N supplementation and interactions between straw type × N supplementation with regard to any of the measured characteristics except for DM intake, which reduced due to the casein supplementation in the ET diet. These results indicate that the alkali treatment and ensilage of barley straw increased digestibility, intake, faecal consistency and urinary pH and dilution but decreased straw alkalinity as well as ruminal and faecal pH.     

Relationship of Progesterone,Bovine Pregnancy-Associated Glycoprotein-1 and Nitric Oxide with Late Embryonic and Early Fetal Mortalities in Dairy Cows

The aim of the present study was to determine the relationship of progesterone (P4), bovine pregnancy-associated glycoprotein-1 (bPAG-1) and nitric oxide (NO) levels with late embryonic (LEM; day 28 to day 42) and early fetal mortalities (EFM; > day 42 to day 56) in dairy cows. Transrectal ultrasonography (6–8 MHz) was performed in 100 Holstein-Friesian cows at days 28, 42 and 56 after artificial insemination (AI; day 0) to diagnose pregnancy and to monitor the fate of the embryo. After ultrasound scanning of each cow, a milk sample was collected for assessment of P4 by an ELISA test and a blood sample was collected for assessment of bPAG-1, by using a double-antibody radioimmunoassay, and serum NO metabolites (nitrate + nitrite). Based on ultrasonographic examinations and bPAG-1-RIA, 41 of 100 inseminated cows were confirmed pregnant at day 28 after AI. Nine cows suffered of LEM, and 6 cows suffered of EFM and the overall pregnancy loss rate was 36.6% (15/41) between days 28 and 56 of pregnancy. By logistic regression analysis, there were no significant relationships between the level of P4 and bPAG-1 at day 28 after AI and the occurrence of LEM and EFM. Also, there were no significant relationships between the levels of P4 and bPAG-1 at day 42 and the occurrence of EFM. On the other hand, a significant relationship (P<0.05) was found between NO level at day 28 and the occurrence of LEM. In conclusion, measurement of the serum NO concentration at day 28 of pregnancy might help to predict the outcome of pregnancy by day 42 in dairy cows but further studies are needed to confirm this.     

Genetic variation in the ovine uncoupling protein 1 gene: association with carcass traits in New Zealand (NZ) Romney sheep,but no association with growth traits in either NZ Romney or NZ Suffolk sheep

The uncoupling protein 1 (UCP1) plays an important role in the regulation of lipolysis and thermogenesis in adipose tissues. Genetic variation within three regions (the promoter, intron 2 and exon 5) of the ovine UCP1 gene (UCP1) was investigated using polymerase chain reaction‐single‐strand conformational polymorphism (PCR‐SSCP) analyses. These revealed three promoter variants (designated A, B and C) and two intron 2 variants (a and b). The association of this genetic variation with variation in lamb carcass traits and postweaning growth was investigated in New Zealand (NZ) Romney and Suffolk sheep. The presence of B in a lamb's genotype was associated with decreased subcutaneous carcass fat depth (V‐GR) (p = 0.004) and proportion of total lean meat yield of loin meat (p = 0.005), and an increased proportion of total lean meat yield of hind‐leg meat (p = 0.018). In contrast, having two copies of C was associated with increased V‐GR (p < 0.001) and proportion of total lean meat yield of shoulder meat (p = 0.009), and a decreased hind‐leg yield (p = 0.032). No associations were found with postweaning growth. These results suggest that ovine UCP1 is a potential gene marker for carcass traits.     

The effect of supplementing leaves of four tannin‐rich plant species with polyethylene glycol on digestibility and zootechnical performance of zebu bulls (Bos indicus)

The effect of supplementing leaves of four tannin‐rich plant species with polyethylene glycol 6000 (PEG) on nutrient intake and digestibility as well as on weight gain, feed conversion ratio (FCR) and N retention of zebu bulls (Bos indicus) was studied. Leaves of Albizia gummifera, Grewia ferruginea, Prunus africana and Syzygium guineense, containing, respectively, 85, 55, 76 and 172 g condensed tannins (CT) per kg dry matter (DM), were combined with natural pasture hay in a ratio of 40:60 on DM basis. The four diets were fed both without and with addition of PEG, at a dose of 40 g per kg DM, to eight zebu bulls during trials of 25 days in an 8 × 8 randomized crossover design. Supplementation with PEG increased nutrient intake, digestibility, FCR, N retention and average daily gain (p < 0.01). A diet × PEG interaction was observed for nutrient intake as well as for crude protein, neutral detergent fibre and acid detergent fibre digestibility (p < 0.05), but the effect size of PEG addition could not be attributed to the CT content as such, and also digestibility without PEG was not related to CT content of the diets. The reason why the efficacy of PEG addition did not relate to the CT content pointed the need to evaluate other factors that can help to predict the efficacy of PEG, for example, tannin type or interaction with other nutrients.     

Faecal nitrogen excretion as an approach to estimate forage intake of wethers

Data from twenty‐two digestibility trials were compiled to examine the relationship between faecal N concentration and organic matter (OM) digestibility (OMD), and between faecal N excretion and OM intake (OMI) by wethers fed tropical or temperate forages alone or with supplements. Data set was grouped by diet type as follows: only tropical grass (n = 204), only temperate grass (n = 160), tropical grass plus supplement (n = 216), temperate grass plus supplement (n = 48), tropical grass plus tropical legume (n = 60) and temperate grass with ruminal infusion of tannins (n = 16). Positive correlation between OMD and either total faecal N concentration (Nfc, % of OM) or metabolic faecal N concentration (Nmetfc, % of OM) was significant for most diet types. Exceptions were the diet that included a tropical legume, where both relationships were negative, and the diet that included tannin extract, where the correlation between OMD and Nfc was not significant. Pearson correlation and linear regressions between OM intake (OMI, g/day) and faecal N excretion (Nf, g/day) were significant for all diet types. When OMI was estimated from the OM faecal excretion and Nfc‐based OMD values, the linear comparison between observed and estimated OMI values showed intercept different from 0 and slope different from 1. When OMI was estimated using the Nf‐based linear regressions, the linear comparison between observed and estimated OMI values showed neither intercept different from 0 nor slope different from 1. Both linear comparisons showed similar R² values (i.e. 0.78 vs. 0.79). In conclusion, linear equations are suitable for directly estimating OM intake by wethers, fed only forage or forage plus supplements, from the amount of N excreted in faeces. The use of this approach in experiments with grazing wethers has the advantage of accounting for individual variations in diet selection and digestion processes and precludes the use of techniques to estimate forage digestibility.     

Volatile fatty acid profile for grass hay or alfalfa hay fed to alpacas (Vicugna pacos)

The purpose of this study was to determine the diurnal composition and concentration of volatile fatty acids (VFA) and to determine VFA composition and concentration differences between stomach compartment 1 (C1) and caecum of alpacas fed grass and alfalfa hay. The study was divided into two experiments. In Experiment 1 (EXP 1), 10 male alpacas (3+ years old, 65 kg BW) were divided into two groups, housed in drylot pens, provided ad libitum water and fed alfalfa (AH) or grass hay (GH) for 30 days. The alpacas were slaughtered and the digestive tract collected, divided into sub‐tract sections, weighed and digesta sampled for pH, dry matter (DM) and NDF. Volatile fatty acid composition and concentration were determined on C1 and caecal material. Four adult male (3+ years old, 60 kg BW), C1 fistulated alpacas were housed in metabolism crates and divided into two forage groups for Experiment 2 (EXP 2). Alpacas were fed the forages as in EXP 1. Diurnal C1 VFA samples were drawn at 1, 3, 6, 9, 12, 18 and 24 h post‐feeding. There were no differences between forages for tract weight, C1 and caecum digesta DM or NDF. Differences were noted (p < 0.05) for pH between forages and sub‐tract site. Volatile fatty acids concentrations were different (p < 0.05) for forage and site, and total VFA was higher for AH than GH (110.6 and 79.1 mm ) and C1 than caecum (40.7 and 27.6 mm ). Proportion of VFA was significant (p < 0.05) for forage and site, C1 acetate highest for GH (84.8 vs. 74.0 mm ) and caecum acetate 83.7 and 76.2 mm for GH and AH respectively. These data demonstrate the level of VFA produced in C1 and the caecum of alpacas and the diurnal VFA patterns. Composition of VFA is similar to other ruminant species.