Thai Native Cattle Research Articles

Optimum Level of Lactobacillus plantarum Supplementation as Probiotic on In Vitro Digestibility and Rumen Fermentation Products in Thai Native Cattle

The objective of this study was to determine in vitro gas production kinetics, and rumen fermentation products of total mixed ration (TMR) supplemented with different level of Lactobacillus plantarum supplementation in Thai native cattle. The experiment design was Completely Randomized Design (CRD). The in vitro procedure was completed using 200 mg DM of TMR and four different concentration of L. plantarum; CON (without supplementation of L. plantarum), T1 (107 CFU / mL of L. plantarum supplementation), T2 (108 CFU / mL of L. plantarum supplementation), and T3 (109 CFU / mL of L. plantarum supplementation). The samples were prepared in three replications and incubated for 96 hours for gas production. Rumen fermentation products (pH, NH3, VFA) and digestibility experiment were done in four replications and incubated for 24 hours. In vitro gas production for 96 hours, gas production from insoluble fraction (b), and potential extent of gas production (|a|+b) were improved in the T1 and T2 groups (P < 0.05). The in vitro dry matter and organic matter digestibility, and true digestibility were particularly enhanced in the T1 group compared to other treatments (P <0.05). The pH and NH3 in this study were significantly affected (P<0.05). The significant improvements on the in vitro rumen fermentation products and digestibility endorse L. plantarum supplementation at concentration of 107 CFU/mL as probiotic candidate.

Comparison of lipopolysaccharide-mediated peripheral blood mononuclear cell activation between Brahman and Brahman × Thai native crossbreed cattle.

Lipopolysaccharide (LPS) is a robust endotoxin known to activate the immune system in cattle. The objective of this study was to investigate the effect of LPS on the morphology, cell viability, malondialdehyde (MDA), nitric oxide (NO), and total antioxidant capacity (TAC) of peripheral blood mononuclear cells (PBMCs) in Brahman and Brahman × Thai native crossbreed cattle. PBMCs were isolated from Brahman and Brahman × Thai native crossbreed cattle and treated with 0, 0.1, 1, and 10 μg/mL Escherichia coli LPS, respectively. Morphological changes in PBMCs were assessed at 24 and 48 h. In addition, we measured PBMC cell viability, MDA, NO, and TAC. LPS stimulation caused cell deformation and partial PBMC area enlargement, but there were no differences between Brahman and Brahman × Thai native crossbreed cattle. Stimulation at all levels did not affect the viability of PBMCs (p > 0.05). MDA and NO levels were significantly higher in Brahman cattle than in Brahman Thai native crossbred cattle (p < 0.05). TAC was significantly higher in Brahman × Thai native crossbred cattle than in Brahman cattle (p < 0.05). Immune cells of crossbreed cattle have a higher activation response to LPS than those of purebred cattle, and native crossbreed beef cattle have a higher antioxidant capacity than purebred beef cattle. This result may explain why hybrid cattle of indigenous breeds are more resistant to disease than purebred cattle.

The Effects of Oxidation on the Physicochemical Properties of Semitendinosus and Vastus Lateralis Muscles from Thai Native Cattle (Bos indicus)

The Effects of Oxidation on the Physicochemical Properties of Semitendinosus and Vastus Lateralis Muscles from Thai Native Cattle (Bos indicus)

Comprehensive Assessment of Greenhouse Gas Emissions From Thai Beef Cattle Production and the Effect of Rice Straw Amendment on the Manure Microbiome

We measured the greenhouse gas (GHG) emissions following beef cattle feeding and evaluated the manure management in northeast Thailand (Khon Kaen) to obtain the country-specific emission factor (EF) and replace the Intergovernmental Panel on Climate Change (IPCC) default value. We fed four Thai native cattle their typical diet of the region and then used the head-cage and dynamic chamber methods to measure the enteric methane (CH4) and GHG emissions during manure storage, respectively. The effect of amending the cattle manure with rice straw on the manure’s GHG emission was evaluated. The manure microbiome was monitored by 16S rRNA gene amplicon sequencing and qPCR assay of the functional genes that are required for the methanogenesis and nitrification/denitrification process. The estimated CH4conversion factor (Ym: 6.87 ± 0.11% gloss energy intake (GEI)) was slightly higher than the IPCC default value. The CH4emission from the manure accounted for 0.69 ± 0.26% GEI. The addition of rice straw slightly lowered the CH4emission from the manure, but the manure microbiome analysis results showed that it significantly reduced the relative abundance of methanogens (Methanobacteriales), and the functional estimation of manure microbiome agreed with this inhibition effect. The addition of rice straw also showed potential mitigation of the N2O emission with lowered nitrification activity and lower nitrifier abundance, but the results were not consistent between runs. Together these findings will be useful for the higher-tier approach to GHG emissions from beef cattle production systems in tropical regions.

Effects of Betaine-Biotin-Chromium Supplementation and Concentrate to Roughage Ratio on Nutrient Utilization Efficiency in Thai Native Cattle

Simple SummaryFeed additives are attracting considerable interest due to the need to effectively improve the level of production, efficiency, and health of animals. A combination of betaine, biotin, and chromium has been developed to enhance nutrient utilization efficiency. Ideally, the addition of a combination of supplements to livestock feed could improve ruminal fermentation, digestibility and nutrient utilization, nitrogen and energy balance, and metabolism.The objective of this study was to evaluate the effects of supplementation with a feed additive containing a combination of betaine, biotin, and chromium (BBC) and concentrate-to-roughage ratio (C:R ratio) on nutrient digestibility, blood metabolites, ruminal fermentation, nitrogen balance, and energy utilization in Thai native beef cattle. Five Thai feedlot native beef bulls at one year old of age and 87.6 ± 15.7 kg of body weight were assigned in a (2 × 2) + 1 augmented factorial experiment according to a 5 × 5 Latin square design with five periods of 21 days. The two levels of BBC were 3 g/kg DM and 6 g/kg DM, and the two ratios of C:R were 60C:40R and 70C:30R. A C:R ratio of 70C:30R without BBC supplementation was used as a negative control. The cattle were offered feed at 3% BW, which provides sufficient energy and protein to support a weight gain of 500 g/day. The results showed that dry matter intake (DMI) and organic matter intake (OMI) were not different (p > 0.05), but the intake of crude protein (CP) and ether extract (EE) was higher (p < 0.05), whereas neutral detergent fiber (NDF) and acid detergent fiber (ADF) were lower (p < 0.05) in the 70C:30R ratio diets compared to the 60:40R ratio diets. Energy balance and nitrogen balance were not influenced (p > 0.05) by the C:R ratio or the addition of BBC. Rumen pH and ammonia-nitrogen (NH3-N) did not differ (p > 0.05) among treatments groups. Total volatile fatty acid (VFA) production was higher (p < 0.05) in bulls fed with the 70C:30R ratio diet. The addition of BBC resulted in a lower (p < 0.01) glucose-to-insulin ratio compared to cattle fed with the control diet. Energy and protein utilization efficiency did not differ (p > 0.05) among the experimental treatment groups, which were higher (p > 0.05) than the control group. In conclusion, BBC supplementation showed greater growth performance of cattle compared to the control. BBC supplementation appeared to improve glucose uptake and insulin sensitivity and energy and protein utilization efficiency. Whether BBC supplementation increases glucose production in the liver remains to be determined in future studies.

Vitamin D2 production and in vitro ruminal degradation of UV-B irradiated vitamin D enriched yeast in Thai native cattle

The purposes of this study were to investigate the optimum UV-B irradiation time needed to produce vitamin D enriched yeast and to promote in vitro ruminal degradation of UV-B irradiated vitamin D enriched yeast in Thai native cattle. Baker’s yeast and S. cerevisiae were irradiated at 0, 2, 4, 8, 10, 12, 16 and 24 hours. The UV-B irradiation of both yeast strains could significantly enhance vitamin D2 to the highest amount at 16 hours. The corn stover and TMR were studied for determination of in vitro ruminal degradation, included three treatments that involved each type of feed, namely feedstuff without supplementation, feedstuff with live yeast supplementation and feedstuff with UV-B irradiated vitamin D enriched yeast. Gas production data of the live yeast group and the UV-B irradiated vitamin D enriched yeast supplementation group, were significantly higher than those of the control groups for both types of feedstuffs. The vitamin D content of the vitamin D enriched yeast supplementation groups were not significantly different from those of the groups subjected to an initial incubation period (10.98 vs. 14.43μg, respectively). Therefore, after a period of irradiation of 16 hours, the two yeasts strain produced the highest vitamin D2 content, while Baker’s yeast produced vitamin D2 at higher amounts than S. cerevisiae. Notably, UV-B irradiated vitamin D enriched yeast improved the in vitro ruminal degradation, while also preventing a loss in the amount of vitamin D that was degraded by the rumen microorganisms.

Meat quality, post-mortem proteolytic enzymes, and myosin heavy chain isoforms of different Thai native cattle muscles.

ObjectiveThis study investigated the meat quality characteristics, endogenous proteolytic enzymes, collagen content, and myosin heavy chain (MyHC) isoforms of different muscles of Thai native cattle (TNC).MethodsInfraspinatus (IF), Longissimus thoracis (LT), and Supraspinatus (SS) muscles were obtained from two TNC breeds, Kho-Lan (KL, n = 7) and Kho-Isaan (KI, n = 7). The muscle and meat characteristics of TNC breeds and their relationship with MyHC expression were examined.ResultsThree MyHC isoforms namely MyHC I, MyHC IIa, and MyHC IIx were detected in the muscles. The KL had higher (p<0.05) MyHC IIx than the KI. The IF muscle had higher (p<0.05) MyHC I compared to other muscles. The LT muscle had the least MyHC I. The LT had higher (p<0.05) MyHC IIx than the IF and SS muscles. The IF presented the least MyHC IIx. The KL had higher (p<0.05) lightness and moisture content and lower crude protein, redness, cooking loss, shear force, and calpastatin than the KI. The glycogen, total collagen, soluble collagen, crude protein, ash contents, and troponin T degradation product of IF and SS were lower (p<0.05) than that of LT. Ether extract in LT was lower (p<0.05) than that of IF and SS. The percentage of MyHC I, MyHC IIa, and MyHC IIx were significantly correlated with muscle and meat characteristics of TNC.ConclusionThese results suggest that the differences in the MyHC isoforms may partly account for the variation in meat quality between breeds and among muscles of TNC.

Feeding cashew nut shell liquid decreases methane production from feces by altering fecal bacterial and archaeal communities in Thai local ruminants.

The effect of feeding cashew nut shell liquid (CNSL) on fecal fermentation products and microbiota was investigated in Thai native cattle and swamp buffaloes. Four of each animal were fed rice straw and concentrate diet with control pellets without CNSL for 4weeks, followed by the same diet with pellets containing CNSL for another 4weeks, so that CNSL was administered at a level of 4g/100kg body weight. Feces were collected the last 2days in each feeding period. CNSL alkyl phenols were recovered from feces (16%-28%) in a similar proportion to those in the diet, indicating that most functional anacardic acid was not selectively removed throughout the digestive tract. In vitro production of gas from feces, particularly methane, decreased with CNSL feeding. The proportion of acetate in feces decreased with CNSL feeding, whereas that of propionate increased, without affecting total short-chain fatty acid concentration. CNSL feeding changed fecal microbial community, particularly in swamp buffaloes, which exhibited decreases in the frequencies of Treponema, unclassified Ruminococcaceae, and Methanomassiliicoccaceae. These results suggest that CNSL feeding alters not only rumen fermentation but also hindgut fermentation via modulation of the microbial community, thereby potentially attenuating methane emission from the feces of ruminant animals.

Cashew nut shell liquid potentially mitigates methane emission from the feces of Thai native ruminant livestock by modifying fecal microbiota.

The methane-mitigating potency of cashew nutshell liquid (CNSL) was evaluated by investigating gas production from batch cultures using feces from Thai native ruminants that had been incubated for different periods. Feces was obtained from four Thai native cattle and four swamp buffaloes reared under practical feeding conditions at the Kasetsart University farm, Thailand. Fecal slurry from the same farm was also included in the analysis. CNSL addition successfully suppressed the methane production potential of feces from both ruminants by shifting short chain fatty acid profiles towards propionate production. Methane mitigation continued for almost 150 days, although the degree of mitigation was more apparent from Day 0 to Day 30. Bacterial and archaeal community shifts with CNSL addition were observed in feces from both ruminants; specifically, Bacteroides increased, whereas Lachnospiraceae and Ruminococcaceae decreased in feces to which CNSL was added. Fecal slurry did not show marked changes in gas production with CNSL addition. The findings showed that the addition of CNSL to the feces of ruminants native to the Southeast Asian region can suppress methane emission. Because CNSL can be easily obtained as a byproduct of the local cashew industry in this region, its on-site application might be ideal.

Nutritional status of grazing Lowline Angus crossbred supplemented with fermented cassava starch residue.

This study aimed to compare growth performance of Lowline Angus crossbred with Thai native cattle under a grazing system with supplementation of fermented cassava starch residue. Three Ruzi grass sub-fields were used for twenty heads of beef cattle for a 7-month experiment from February to August 2017. Yeast, molasses, and urea-fermented cassava starch residue was offered at 1.50% BW of animal. Blood metabolite and fecal composition were determined for health and nutritional stage assessment. The temperature-humidity index was highest (75.6-84.6) in April. Overall growth rate of beef cattle was not significantly different among breeds except in the first month when the native had greater weight gain than the crossbred. Average daily gain was 353 and 345g for Thai native and its crossbred with Lowline Angus, respectively. Blood triglyceride concentration sampled at 7months of the native was higher than that of the crossbred; in contrast, blood cholesterol of the crossbred tended to be higher than that of the native. Other blood metabolites including glucose, cholesterol, urea nitrogen, creatinine, total protein, albumin, and globulin were comparable between breeds. The native and the crossbred were similar in fecal composition, ruminal fermentation end-products (ammonia nitrogen and volatile fatty acids), and microbial population. Therefore, under grazing condition with low-quality feed supplementation, Thai native beef cattle and its Lowline Angus crossbred had similar growth rate, health, and nutritional status.

Effect of cashew nut shell liquid feeding on fermentation and microbiota in the rumen of Thai native cattle and swamp buffaloes

Effects of cashew nut shell liquid (CNSL) feeding on rumen fermentation and microbial profiles were investigated using Thai native cattle (n = 4) and swamp buffaloes (n = 4). Rumen fistulated animals were assigned to an experiment in one factor design: they were fed a concentrate (1 kg) and rice straw (90% of ad libitum intake) diet supplemented with control pellets followed by CNSL-containing pellets for 4 wk each (control and CNSL periods, respectively). Rumen content was sampled at the end of the control period (d 27 and 28) and at 2 wk (d 13 and 14) and 4 wk (d 27 and 28) of the CNSL period to monitor rumen characteristics. Feed intake, ruminal DM disappearance, ruminal pH and ammonia concentration were not obviously affected by CNSL feeding. Methane production potential, monitored by a batch culture system supplemented with the same diet formula, was decreased by 53% and 73%, after 4-wk CNSL feeding to Thai native cattle and swamp buffaloes, respectively. Although volatile fatty acid level in the rumen was not changed by CNSL feeding, propionate proportion was greatly elevated by 23% and 31% in native cattle and buffaloes, respectively, after 4-wk CNSL feeding. Enhanced propionate was observed even in the 2-wk samples. Results of quantitative PCR analysis showed that although numbers of methanogenic archaea in the rumen did not change, protozoa were decreased and some bacterial groups including genus Prevotella were increased by CNSL feeding in both native cattle and buffaloes. This is in agreement with the results of Miseq analysis of 16S rRNA genes of rumen microbes, which showed increases of Prevotella with CNSL feeding. Increase of Succiniclasticum and decrease of unclassified Bacteroidales by CNSL were also observed for both native cattle and buffaloes. Changes in archaeal community were also similar between these two genera of ruminants. These ruminal responses indicate that CNSL feeding is useful for modulating rumen fermentation in Thai local ruminants, major contributors to methane emission in this area. This is the first report describing the effect of CNSL feeding on rumen fermentation in relation to detailed analysis of rumen microbial community.

Growth performance of Lowline Angus x Thai native crossbred beef under tropical condition.

Thai native cattle (Bos indicus) have high fertility rates and strong mothering abilities; however, their slight size, slow growth rate and low meat quality have not proved suitable for a commercial fattening system. Their progeny from crossbreeding with exotic sire particularly the Bos Taurus could present greater production performance. Lowline Angus sires and frozen semen were used to produce Lowline Angus x Thai native crossbreds. All cattle were raised in the same condition which was mainly through a grazing system. Throughout 5years of data collection, calves' gender, birth weight, and weight gains were recorded until 1year of age. There was no interaction effect between calves' gender, breed, and birth season on weight at birth and yearling, as well as growth rate. The birth weight of male calves (14.0kg) were greater than female calves (13.3kg). The calves' birth weights did not differ between levels of Lowline Angus blood, but all crossbred males were found to be significantly bigger than indigenous females. It must be noted that yearling weight did not differ between breeds. However, females 75% Lowline Angus, 25% Thai native crossbred (139.3kg) weighed significantly higher than Thai native purebred females (115.9kg). The calves' birth weights had positive correlation with Lowline Angus blood levels: birth weights increased when Lowline Angus blood levels were increased. The sharpness in the growth curve of Lowline Angus crossbreds was higher than purebred Thai indigenous cattle. Moreover, the 25% Lowline Angus crossbred had the highest graph slope as opposed to the 50% or 75% Lowline Angus crossbred. The growth performance of Lowline Angus x Thai native crossbred was shown unsuccessful under low-quality grazing situation. Additive effect of the crossbred presented quite low but well adapted to tropical environment. Greater productivity performance of the crossbred possibly will be excess with a higher quality feedlot condition.

Effect of Barn Roof Design on General Physiological Changes, Animal Welfare Behavior and Growth Performance of Thai Native Cattle in Rural Conditions in Sakon Nakhon Province, Thailand

Effect of Barn Roof Design on General Physiological Changes, Animal Welfare Behavior and Growth Performance of Thai Native Cattle in Rural Conditions in Sakon Nakhon Province, Thailand

Enteric methane emissions, energy partitioning, and energetic efficiency of zebu beef cattle fed total mixed ration silage.

ObjectiveThe main objective of this study was to evaluate the effect of different feeding levels of a total mixed ration silage-based diet on feed intake, total tract digestion, enteric methane emissions, and energy partitioning in two beef cattle genotypes.MethodsSix mature bulls (three Thai natives, and three Thai natives - Charolais crossbreeds) were assigned in a replicated 3×3 Latin square design, with cattle breed genotype in separate squares, three periods of 21 days, and three energy feeding above maintenance levels (1.1, 1.5, and 2.0 MEm, where MEm is metabolizable energy requirement for maintenance). Bulls were placed in a metabolic cage equipped with a ventilated head box respiration system to evaluate digestibility, record respiration gases, and determine energy balance.ResultsIncreasing the feeding level had no significant effect on digestibility but drastically reduced the enteric methane emission rate (p<0.05). Increasing the feeding level also significantly increased the energy retention and utilization efficiency (p<0.01). The Thai native cattle had greater enteric methane emission rate, digestibility, and energy utilization efficiency than the Charolais crossbred cattle (p<0.05). The daily metabolizable energy requirement for maintenance in Thai native cattle (388 kJ/kg BW0.75, where BW0.75 is metabolic body weight) was 15% less than that in Charolais crossbred cattle (444 kJ/kg BW0.75).ConclusionOur results suggested that the greater feeding level in zebu beef cattle fed above maintenance levels resulted in improved energy retention and utilization efficiency because of the reduction in enteric methane energy loss. The results also indicated higher efficiency of metabolisable energy utilization for growth and a lower energy requirement for maintenance in Bos indicus than in Bos taurus.

Effects of supplementary desalted mother liquor as replacement of commercial salt in diet for Thai native cattle on digestibility, energy and nitrogen balance, and rumen conditions.

Four Thai native cattle were used in a 4×4 Latin square design experiment to evaluate the availability of desalted mother liquor (DML) as replacement of salt in concentrate. Each cattle was assigned to one of the following concentrate feeding treatments: C1, 1% NaCl was added as salt; C2, 2% NaCl was added as salt; D1, 1% NaCl was replaced by DML; D2, 2% NaCl was replaced by DML, on a dry matter (DM) basis. The animals were fed rice straw and experimental concentrates (40:60) at 1.9% of body weight on a DM basis, daily. Acid detergent fiber expressed exclusive of residual ash (ADFom) digestibility in DML treatment was higher than salt treatment (p<.05) and D2 feeding showed the highest value (60.8%). There were no significant differences in blood metabolites, nitrogen retention, ruminal ammonia nitrogen, methane emission or energy efficiency among treatments. Molar percent of acetate on volatile fatty acids in rumen fluid 4hr post-feeding tended to be higher in DML treatment than salt treatment (p=.08). The results indicated that adding DML could improve ADFom digestibility and salt could be replaced by DML up to 2% as NaCl in concentrate without adverse effects on nitrogen balance, rumen conditions, blood metabolites and methane emission.

Transfer of Thai Native Cattle Feeding Technology to Cattle Farmers in Rural Communities in Sakon Nakhon Province, Thailand, in Response to Global Warming to Produce Cattle with the Characteristics of Physiological Adaptability, Heat Tolerance and Increased Production Performance

Transfer of Thai Native Cattle Feeding Technology to Cattle Farmers in Rural Communities in Sakon Nakhon Province, Thailand, in Response to Global Warming to Produce Cattle with the Characteristics of Physiological Adaptability, Heat Tolerance and Increased Production Performance

Feed intake, digestibility and energy partitioning in beef cattle fed diets with cassava pulp instead of rice straw.

ObjectiveThis study was conducted to assess the effects of replacing rice straw with different proportions of cassava pulp on growth performance, feed intake, digestibility, rumen microbial population, energy partitioning and efficiency of metabolizable energy utilization in beef cattle.MethodsEighteen yearling Thai native beef cattle (Bos indicus) with an average initial body weight (BW) of 98.3±12.8 kg were allocated to one of three dietary treatments and fed ad libitum for 149 days in a randomized complete block design. Three dietary treatments using different proportions of cassava pulp (100, 300, and 500 g/kg dry matter basis) instead of rice straw as a base in a fermented total mixed ration were applied. Animals were placed in a metabolic pen equipped with a ventilated head box respiration system to determine total digestibility and energy balance.ResultsThe average daily weight gain, digestible intake and apparent digestibility of dry matter, organic matter and non-fiber carbohydrate, total protozoa, energy intake, energy retention and energy efficiency increased linearly (p<0.05) with an increasing proportion of cassava pulp in the diet, whereas the three main types of fibrolytic bacteria and energy excretion in the urine (p<0.05) decreased. The metabolizable energy requirement for the maintenance of yearling Thai native cattle, determined by a linear regression analysis, was 399 kJ/kg BW0.75, with an efficiency of metabolizable energy utilization for growth of 0.86.ConclusionOur results demonstrated that increasing the proportion of cassava pulp up to 500 g/kg of dry matter as a base in a fermented total mixed ration is an effective strategy for improving productivity in zebu cattle.

Uterine artery flow velocity waveform, arterial flow indices, follicular dynamics, and sex hormones during preovulatory period in synchronized ovulatory cycle of Bos indicus beef cows

A greater understanding of the uterine artery’s (UtA) biology is essential to the increase in female reproductive abilities. The UtA flow velocity waveform, blood flow volume (BFV), pulsatility and resistance indices (PI and RI), blood flow velocities, dynamics of the dominant follicle (DF), and estradiol (E2) and progesterone (P4) levels in an induced ovulatory cycle were evaluated in Thai native cattle. Twenty cows were induced with synchronized ovulation through a P4-releasing device, from Day −9 to Day −4, concurrent with the administration of two doses of a gonadotropin-releasing hormone on Day −9 and Day −1, and two doses of prostaglandin F2α on Day −4 and 8 h later. Day 0 was designated as the day of ovulation. The cows underwent Doppler sonographic determination and blood collection from Day −4 to Day 0. The cows were classified in the non-ovulating (n = 5) and ovulating groups (n = 15). The ovulating cows presented higher BFV values, blood flow velocities, DF growth rates, and E2 levels; yet lower PI values and P4 concentrations, than those of the non-ovulating cows. The BFV values and the blood flow velocities were greater, but the RI and PI values were lower in the ovulatory side UtA than in the contraovulatory side UtA. The BFV values were positively correlated with blood flow velocities, DF growth rates and E2 concentrations in the ovulating cows; confirming the importance of UtA blood flow, follicular growth, and E2-vasodilation during preovulatory phase in the induced ovulatory cycle of Bos indicus beef cows.

Studies on supplementary desalted mother liquor on digestibility of nutrients, ruminal fermentation, and energy and nitrogen balance in Thai native cattle.

Four Thai native steers were used to determine the adequate levels of supplementary desalted mother liquor (DML) for energy and nitrogen balances and ruminal fermentation. The crude protein and sodium chloride contents of DML were 25.5% and 60.3% on a dry matter (DM) basis, respectively. A 4×4 Latin square design experiment was conducted by adding different amounts of DML to three experimental diets (T1: 1.1%, T2: 2.2%, T3: 3.4% sodium chloride concentration with supplementary DML on a DM basis) and comparing their effects with those of a control diet (C) containing 1.0% commercial salt on a DM basis. The animals were given the experimental diets and rice straw daily at 1.2% and 0.8% of body weight, respectively, on a DM basis. No significant differences in the apparent digestibility of nutrients were observed among treatments. T3 achieved the lowest nitrogen retention (P<0.05), followed by C, T2 and T1. The ratios of energy retention to gross energy were higher in T1 and T3 than T2, and that in C was lowest (P<0.05). Supplementary NaCl concentration at 1% and 2% can be replaced with DML without an adverse effect on the digestibility of nutrients or on the nitrogen and energy retention.

Comparison of three superovulation protocols with or without GnRH treatment at the time of artificial insemination on ovarian response and embryo quality in Thai native heifers.

To optimize the superovulation protocol in Thai native cattle, the present research was designed to (1) compare three different protocols designed to induce superstimulation and (2) study the effect of gonadotropin-releasing hormone (GnRH) administration at insemination time (to induce ovulation) on ovarian follicular activities in terms of the number of large follicles, corpora lutea (CLs) and unovulated follicles, and the number and quality of ova/embryos recovered in Thai native heifers. Initially, the estrous cycles of animals (n = 36) at unknown stages were synchronized by two prostaglandin F2α (PGF2α) injections at an interval of 12days. Follicular development of heifers was randomly superstimulated with one of three different treatment protocols: treatment A-a total of 100mg of pituitary-derived FSH (pFSH; Folltropin®-V) administered in eight decreasing doses; treatment B-a single dose of 100mg pFSH dissolved in 30% (w/v) polyvinylpyrrolidone; or treatment C-ablation of all follicles ≥5mm with a single dose of pFSH. All heifers received PGF2α 48h after the initiation of FSH treatment to induce luteolysis from the previous cycle, and they were twice inseminated at 12 and 24h after the onset of estrus. Heifers in each treatment were assigned to be injected or not with GnRH at the time of first insemination with frozen/thawed semen to induce ovulation. About 7days after artificial insemination (AI), ova/embryos were collected and classified. The numbers of large follicles at the onset of estrus were not statistically significantly different; meanwhile, the maximum diameters of follicles at the time of first insemination in treatment C were smaller compared with the other treatment groups (p < 0.001). The administration of GnRH at the first insemination time resulted in a greater number of CLs and fewer unovulated follicles at the time of ova/embryo collection (p = 0.001), which subsequently resulted in a higher number of total ova/embryos recovered (p = 0.030). Among heifers treated with different superstimulation protocols, the ablation of all follicles ≥5mm in diameter before superstimulation (treatment C) resulted in significantly higher quality of fertilized ova and transferable embryos (p = 0.001). In summary, it could be inferred that GnRH treatment improved ovarian function rather than embryo quality. Dominant follicle ablation prior to superstimulation is preferable for collecting a greater number of transferable embryos.