Integration of the effects of animal and dietary factors on total dry matter intake of dairy cows fed silage-based diets

An empirical regression model for the prediction of total dry matter intake (DMI) of dairy cows was developed and compared with four published intake models. The model was constructed to include both animal and dietary factors, which are known to affect DMI. For model development, a data set based on individual cow data from 10 change-over and four continuous milk production studies was collected (n = 1554). Relevant animal (live weight (LW), days in milk (DIM), parity and breed) and dietary (total and concentrate DMI, concentrate composition, forage digestibility and fermentation quality) data were collected. The model factors were limited to those that are available before the diets are fed to animals, that is, standardized energy corrected milk (sECM) yield, LW, DIM and diet quality (total diet DMI index (TDMI index)). As observed ECM yield is a function of both the production potential of the cow and diet quality, ECM yield standardized for DIM, TDMI index and metabolizable protein concentration was used in modelling. In the individual data set, correlation coefficients between sECM and TDMI index or DIM were much weaker (0.16 and 0.03) than corresponding coefficients with observed ECM (0.65 and 0.46), respectively. The model was constructed with a mixed model regression analysis using cow within trial as a random factor. The following mixed model was estimated for DMI prediction: DMI (kg DM/day) = -2.9 (±0.56)+0.258 (±0.011) × sECM (kg/day) + 0.0148 (±0.0009) × LW (kg) -0.0175 (±0.001) × DIM -5.85 (±0.41) × exp (-0.03 × DIM) + 0.09 (±0.002) × TDMI index. The mixed DMI model was evaluated with a treatment mean data set (207 studies, 992 diets), and the following relationship was found: Observed DMI (kg DM/day) = -0.10 (±0.33) + 1.004 (±0.019) × Predicted DMI (kg DM/day) with an adjusted residual mean square error of 0.362 kg/day. Evaluation of the residuals did not result in a significant mean bias or linear slope bias, and random error accounted for proportionally >0.99 of the error. In conclusion, the DMI model developed is considered robust because of low mean prediction error, accurate and precise validation, and numerically small differences in the parameter values of model variables when estimated with mixed or simple regression models. The Cornell Net Carbohydrate and Protein System was the most accurate of the four other published DMI models evaluated using individual or treatment mean data, but in most cases mean and linear slope biases were relatively high, and, interestingly, there were large differences in both mean and linear slope biases between the two data sets.     

Prediction of enteric methane production,yield, and intensity in dairy cattle using an intercontinental database

Enteric methane (CH₄) production from cattle contributes to global greenhouse gas emissions. Measurement of enteric CH₄ is complex, expensive, and impractical at large scales; therefore, models are commonly used to predict CH₄ production. However, building robust prediction models requires extensive data from animals under different management systems worldwide. The objectives of this study were to (1) collate a global database of enteric CH₄ production from individual lactating dairy cattle; (2) determine the availability of key variables for predicting enteric CH₄ production (g/day per cow), yield [g/kg dry matter intake (DMI)], and intensity (g/kg energy corrected milk) and their respective relationships; (3) develop intercontinental and regional models and cross‐validate their performance; and (4) assess the trade‐off between availability of on‐farm inputs and CH₄ prediction accuracy. The intercontinental database covered Europe (EU), the United States (US), and Australia (AU). A sequential approach was taken by incrementally adding key variables to develop models with increasing complexity. Methane emissions were predicted by fitting linear mixed models. Within model categories, an intercontinental model with the most available independent variables performed best with root mean square prediction error (RMSPE) as a percentage of mean observed value of 16.6%, 14.7%, and 19.8% for intercontinental, EU, and United States regions, respectively. Less complex models requiring only DMI had predictive ability comparable to complex models. Enteric CH₄ production, yield, and intensity prediction models developed on an intercontinental basis had similar performance across regions, however, intercepts and slopes were different with implications for prediction. Revised CH₄ emission conversion factors for specific regions are required to improve CH₄ production estimates in national inventories. In conclusion, information on DMI is required for good prediction, and other factors such as dietary neutral detergent fiber (NDF) concentration, improve the prediction. For enteric CH₄ yield and intensity prediction, information on milk yield and composition is required for better estimation.     

High-throughput sequencing of hair follicle development-related micrornas in cashmere goat at various fetal periods

Inner Mongolia cashmere goat marks a precious gerplasm genetic resource due to its excellent cashmere traits. Therefore, it is of crucial importance to investigate the cashmere development mechanism of cashmere goat and to search for the important cashmere growth-related candidate genes. Fetal skin samples at 10 different periods of cashmere goat were collected in this research. Moreover, high-throughput sequencing was conducted on RNA samples from side skin of cashmere goat fetuses collected at three critical periods of skin hair follicle initiation, growth and development (namely, 45, 55 and 65?days) after balanced mix in line with the previous research results. Meanwhile, 3 samples at corresponding periods were used as the biological duplications. Data regarding microRNA and mRNA expression in skin and hair follicles of cashmere goats at various fetal periods were obtained using the high-throughput sequencing method. The results indicated that microRNAs in the oar-let-7 and oar-miR-200 families in 55?days and 66?days of pregnancy samples had been notably up-regulated relative to those in 45?days of pregnancy samples. This revealed that they might be the critical microRNAs in hair follicle development.     

藏山羊KLF8基因克隆及组织表达分析

本试验旨在获得藏山羊KLF8基因序列,并分析其生物学特征,同时阐明该基因在不同组织中的表达情况。利用RT-PCR技术克隆藏山羊KLF8基因序列,利用实时荧光定量PCR (quantitative real-time PCR,qPCR)检测其在藏山羊各个组织中的表达丰度。结果表明,获得藏山羊KLF8基因序列1 069 bp,其中包含CDS区1 008 bp,5'UTR序列28 bp和3'UTR序列33 bp,共编码335个氨基酸,为不稳定亲水碱性蛋白。KLF8基因在藏山羊的肺脏组织中表达水平最高,极显著高于其他组织(p<0.01)。本研究为进一步阐明KLF8基因在藏山羊中的生物学功能提供了依据。     

Effects of starch-rich or lipid-supplemented diets that induce milk fat depression on rumen biohydrogenation of fatty acids and methanogenesis in lactating dairy cows

Optimizing milk production efficiency implies diets allowing low methane (CH₄) emissions and high dairy performance. We hypothesize that nature of energy (starch v. lipids) and lipid supplement types (monounsaturated fatty acid (MUFA) v. polyunsaturated fatty acid (PUFA) mitigate CH₄ emissions and can induce low milk fat content via different pathways. The main objective of this experiment was to study the effects of starch-rich or lipid-supplemented diets that induce milk fat depression (MFD) on rumen biohydrogenation (RBH) of unsaturated fatty acids (FA) and enteric CH₄ emissions in dairy cows. Four multiparous lactating Holstein cows (days in milk=61±11 days) were used in a 4×4 Latin square design with four periods of 28 days. Four dietary treatments, three of which are likely to induce MFD, were based (dry matter basis) on 56% maize silage, 4% hay and 40% concentrates rich in: (1) saturated fatty acid (SFA) from Ca salts of palm oil (PALM); (2) starch from maize grain and wheat (MFD-Starch); (3) MUFA (cis-9 C18:1) from extruded rapeseeds (MFD-RS); and (4) PUFA (C18:2n-6) from extruded sunflower seeds (MFD-SF). Intake and milk production were measured daily. Milk composition and FA profile, CH₄ emissions and total-tract digestibility were measured simultaneously when animals were in open-circuit respiration chambers. Fermentation parameters were analysed from rumen fluid samples taken before feeding. Dry matter intake, milk production, fat and protein contents, and CH₄ emissions were similar among the four diets. We observed a higher milk SFA concentration with PALM and MFD-Starch, and lower milk MUFA and trans-10 C18:1 concentrations in comparison to MFD-RS and MFD-SF diets, while trans-11 C18:1 remained unchanged among diets. Milk total trans FA concentration was greater for MFD-SF than for PALM and MFD-Starch, with the value for MFD-RS being intermediate. Milk C18:3n-3 content was higher for MFD-RS than MFD-SF. The MFD seems more severe with MFD-SF and MFD-RS than PALM and MFD-Starch diets, because of a decrease in milk SFA concentration and a stronger shift from trans-11 C18:1 to trans-10 C18:1 in milk. The MFD-SF diet increased milk trans FA (+60%), trans-10 C18:1 (+31%), trans-10,cis-12 CLA (+27%) and PUFA (+36%) concentrations more than MFD-RS, which explains the numerically lowest milk fat yield and indicates that RBH pathways of PUFA differ between these two diets. Maize silage-based diets rich in starch or different unsaturated FA induced MFD with changes in milk FA profiles, but did not modify CH₄ emissions.     

Effects of nitrogen fertilisation rate and maturity of grass silage on methane emission by lactating dairy cows

Grass silage is typically fed to dairy cows in temperate regions. However, in vivo information on methane (CH₄) emission from grass silage of varying quality is limited. We evaluated the effect of two rates of nitrogen (N) fertilisation of grassland (low fertilisation (LF), 65 kg of N/ha; and high fertilisation (HF), 150 kg of N/ha) and of three stages of maturity of grass at cutting: early maturity (EM; 28 days of regrowth), mid maturity (MM; 41 days of regrowth) and late maturity (LM; 62 days of regrowth) on CH₄ production by lactating dairy cows. In a randomised block design, 54 lactating Holstein–Friesian dairy cows (168±11 days in milk; mean±standard error of mean) received grass silage (mainly ryegrass) and compound feed at 80 : 20 on dry matter basis. Cows were adapted to the diet for 12 days and CH₄ production was measured in climate respiration chambers for 5 days. Dry matter intake (DMI; 14.9±0.56 kg/day) decreased with increasing N fertilisation and grass maturity. Production of fat- and protein-corrected milk (FPCM; 24.0±1.57 kg/day) decreased with advancing grass maturity but was not affected by N fertilisation. Apparent total-tract feed digestibility decreased with advancing grass maturity but was unaffected by N fertilisation except for an increase and decrease in N and fat digestibility with increasing N fertilisation, respectively. Total CH₄ production per cow (347±13.6 g/day) decreased with increasing N fertilisation by 4% and grass maturity by 6%. The smaller CH₄ production with advancing grass maturity was offset by a smaller FPCM and lower feed digestibility. As a result, with advancing grass maturity CH₄ emission intensity increased per units of FPCM (15.0±1.00 g CH₄/kg) by 31% and digestible organic matter intake (33.1±0.78 g CH₄/kg) by 15%. In addition, emission intensity increased per units of DMI (23.5±0.43 g CH₄/kg) by 7% and gross energy intake (7.0±0.14% CH₄) by 9%, implying an increased loss of dietary energy with advancing grass maturity. Rate of N fertilisation had no effect on CH₄ emissions per units of FPCM, DMI and gross energy intake. These results suggest that despite a lower absolute daily CH₄ production with a higher N fertilisation rate, CH₄ emission intensity remains unchanged. A significant reduction of CH₄ emission intensity can be achieved by feeding dairy cows silage of grass harvested at an earlier stage of maturity.     

Effects of concentrate type and chromium propionate on insulin sensitivity,productive and reproductive parameters of lactating dairy cows consuming excessive energy

This experiment compared insulin sensitivity parameters, milk production and reproductive outcomes in lactating dairy cows consuming excessive energy, and receiving in a 2×2 factorial arrangement design: (1) concentrate based on ground corn (CRN; n=13) or citrus pulp (PLP; n=13), and (2) supplemented (n=14) or not (n=12) with 2.5 g/day of chromium (Cr)-propionate. During the experiment (day 0 to 182), 26 multiparous, non-pregnant, lactating Gir×Holstein cows (initial days in milk=80±2) were offered corn silage for ad libitum consumption, and individually received concentrate formulated to allow diets to provide 160% of their daily requirements of net energy for lactation. Cow BW and body condition score (BCS) were recorded weekly. Milk production was recorded daily and milk samples collected weekly. Blood samples were collected weekly before the morning concentrate feeding. Glucose tolerance tests (GTT; 0.5 g of glucose/kg of BW) were performed on days −3, 60, 120 and 180. Follicle aspiration for in vitro embryo production was performed via transvaginal ovum pick-up on days −1, 82 and 162. No treatment differences were detected (P⩾0.25) for BW and BCS change during the experiment. Within weekly blood samples, concentrations of serum insulin and glucose, as well as insulin : glucose ratio were similar among treatments (P⩾0.19), whereas CRN had less (P<0.01) non-esterified fatty acid concentrations compared with PLP (0.177 v. 0.215 mmol/l; SEM=0.009). During the GTT, no treatment differences were detected (P⩾0.16) for serum glucose concentration, glucose clearance rate, glucose half-life and insulin : glucose ratio. Serum insulin concentrations were less (P=0.04) in CRN supplemented with Cr-propionate compared with non-supplemented CRN (8.2 v. 13.5 µIU/ml, respectively; SEM=1.7), whereas Cr-propionate supplementation did not impact (P=0.70) serum insulin within PLP cows. Milk production, milk fat and solid concentrations were similar (P⩾0.48) between treatments. However, CRN had greater (P<0.01) milk protein concentration compared with PLP (3.54% v. 3.14%, respectively; SEM=0.08). No treatment differences were detected (P⩾0.35) on number of viable oocytes collected and embryos produced within each aspiration. In summary, feeding a citrus pulp-based concentrate to lactating dairy cows consuming excessive energy did not improve insulin sensitivity, milk production and reproductive outcomes, whereas Cr-propionate supplementation only enhanced insulin sensitivity in cows receiving a corn-based concentrate during a GTT.     

Configurations of germinal vesicle (GV) chromatin in the goat differ from those of other species

Configuration of germinal vesicle (GV) chromatin has been studied and found correlated with the developmental competence of oocytes in several mammalian species. A common feature in the configuration of GV chromatin in the species studied so far is that the diffuse chromatin (the so called "NSN" pattern) condenses into a perinucleolar ring (the so called "SN" configuration) with follicular growth. However, no study has been published on the configuration of GV chromatin in the goat. Nor is it known whether the perinucleolar ring of condensed chromatin (CC) in an oocyte represents a step toward final maturation or atresia. Changes in configurations of GV chromatin and RNA synthesis during goat oocyte growth, atresia and maturation in vivo and in vitro were investigated in this study. Based on both the size of nucleoli and the degree of chromatin condensation, the GV chromatin of goat oocytes was classified into GV1 characterized by large nucleoli and diffuse chromatin, GV2 with medium-sized nucleoli and condensed net-like (GV2n) or clumped (GV2c) chromatin, GV3 with small nucleoli and net-like (GV3n) or clumped (GV3c) chromatin, and GV4 with no nucleolus but clumped chromatin. The results showed that (i) the configurations of GV chromatin in the goat differ from those of other species in that the chromatin did not condense into a perinucleolar ring; (ii) most of the goat oocytes are synchronized at the GV3n configuration before GVBD; (iii) the GVn pattern might represent a healthy state, but the GVc an atretic state; (iv) in both goats and mice, the GC-specific (Chromomycin A3, CMA3) and the AT-specific (Hoechst 33342) fluorochromes followed the same pattern of distribution in GV chromatin; (v) the nucleolar size decreased significantly with oocyte growth and maturation in vivo and in vitro; and (vi) goat oocytes began GVBD at 8 hr and had completed it by 20 hr after onset of estrus. The peculiar configuration of GV chromatin of goat oocytes can be a useful model for studies of morphological and functional changes of different nuclear compartments during the cell cycle and cell differentiation, and the functional differentiation between GV3n and GV3c might be used for reference to the question whether the "SN" configuration in other species inclines toward ovulation or atresia.     

山羊KAP6-1.2基因的克隆表达及分析

目的：研究角蛋白关联蛋白KAP6-1.2对不同品种羊绒和羊毛在核苷酸和氨基酸水平上的影响及在山羊皮肤中的定位表达。方法：以阿尔巴斯白绒山羊KAP6-1.2 cDNA设计特异引物,扩增5种山羊的KAP6-1.2基因的编码区,克隆并测序。制备KAP6-1.2 cRNA探针,通过组织切片原位杂交在皮肤中进行定位表达分析。结果：6种山羊的KAP6-1.2在核苷酸和氨基酸水平上高度同源,仅吐根堡奶山羊的编码区有2个碱基与其他5种山羊不同,导致编码的两个氨基酸残基也发生了改变。原位杂交结果显示,KAP6-1.2 mRNA在10月份皮肤、胚胎125d皮肤、胚胎115d皮肤初级和次级毛囊的皮质层均有强烈的表达。结论：KAP6-1.2的核苷酸序列和氨基酸序列在不同地区、不同品种山羊中高度保守,在胚胎和成年山羊皮肤的初级和次级毛囊的皮质层均有强烈的表达。     

Cloned goats (Capra hircus) from adult ear cells

The average number of available oocytes recovered per ovary collected during the breeding season in dairy goats was 5.5 (1815/330). 66.17% (1201/1815) of oocytes extruded the first polar body after maturation in vitro for 20 h. 75.44% (906/1201) of matured oocytes with membrane evagination around the MII chromosomes were enucleated. Ear skin fibroblast cells were derived from an adult female dining Grey goat (C. hircus). The cells were cryopreserved in liquid nitrogen after passage 2. Thawed cells were further cultured for 3-6 passages and were subjected to serum starvation by 0.5% FBS for 2-10 d, then used as donor cells for nuclear transfer. 98.12% (889/906) of the enucleated oocytes were reconstructed by intracytoplasmic injection of karyoplast. The reconstructed embryos were activated by 5μ mol/L ionomycin for 4.5 min and further activated by culturing with 6-dimethylaminopurine (6-DMAP) for 3 h. After 36 h of culture in mCR1aaBF, 76.69% (645/841) of the cloned embryos cleaved. There were no signifi