Effects of Antidesma thwaitesianum Muell. Arg. pomace as a source of plant secondary compounds on digestibility,rumen environment,hematology, and milk production in dairy cows

Mao pomace meal (MPM) contains condensed tannins and saponins at 92 and 98 g/kg, respectively, and these substances can be used to manipulate ruminal fermentation in ruminant. Four multiparous lactating Holstein cows with 45 ± 5 days in milk were randomly assigned according to a 4 × 4 Latin square design to receive four different levels of MPM supplementation at 0, 100, 200, and 300 g/head/day, respectively. Cows were fed with concentrate diets at 1:1.5 of concentrate to milk yield ratio and urea‐treated (3%) rice straw was fed ad libitum. The results revealed that feed intake, nutrient digestibility, blood urea nitrogen, and hematological parameters were not affected by MPM supplementation (p > 0.05). However, ruminal pH and propionate were increased quadratically (p < 0.05) in cows receiving MPM whereas acetate, acetate to propionate ratio and estimate methane production were decreased (p < 0.05). Supplementation of MPM linearly decreased ruminal ammonia nitrogen and protozoal population at 4 hr postfeeding (p < 0.05). Milk production and milk composition were similar among treatments (p > 0.05). In conclusion, supplementation of MPM at 200 g/head/day could modify ruminal fermentation and reduce methane production without adverse effect on feed intake, digestibility, hematological parameters, and milk production in dairy cows.     

Effect of dried Sesbania sesban leaves supplementation on milk yield,feed intake,and digestibility of Holstein Friesian X Zebu (Arado) crossbred dairy cows

This experiment was conducted to investigate effect of dried Sesbania sesban leaves supplementation on milk yield, feed intake and digestibility of Holstein Frisian X Zebu (Arado) crossbred dairy cows. Twelve cows at midlactation (155.83?±?4.49 days of lactation), second parity, and 442.21?±?3.40 kg average live body weight were randomly assigned to one of four dietary treatments according to a randomized complete block design. Cows were blocked according to their daily milk yield into three blocks of four animals each. Cows were fed a basal diet (control) or a basal diet supplemented with 1.25 kg/day dried Sesbania sesban leaves, 2 kg/day dried Sesbania sesban leaves and 2.75 kg/day dried Sesbania sesban leaves on a dry matter basis for 8 weeks. Total dry matter intake, nutrient intake, milk yield, dry matter digestibility, and nutrient digestibility showed significant variation among treatments. Cows supplemented with the highest level of Sesbania sesban (2.75 kg/day) had higher total dry matter and nutrient intake. Similarly, cows supplemented with 2 and 2.75 kg/day had higher milk yield than the nonsupplemented cows (up to 11.3 and 16.2%, respectively). Digestibility was lower for the nonsupplemented cows compared to cows supplemented with 2 and 2.75 kg/day dried Sesbania sesban leaves but statistically similar to the cows supplemented with 1.25 kg/day dried Sesbania sesban leaves. Supplementation with 2.75 kg/day Sesbania sesban resulted in higher organic matter digestibility (OMD) compared to the control. Crude protein digestibility (CPD), neutral detergent fiber digestibility (NDFD), and acid detergent fiber digestibility (ADFD) were significantly affected by Sesbania sesban supplementation. The nonsupplemented cows had lower CPD, NDFD, and ADFD. These results indicate that dried Sesbania sesban leaves supplementation to dairy increases total DM intake, digestibility, and milk yield.

     

Effect of dietary supplementation of rutin on lactation performance,ruminal fermentation and metabolism in dairy cows

The effect of long‐term dietary supplementation with rutin on the lactation performance, ruminal fermentation and metabolism of dairy cows were investigated in this study. Twenty multiparous Chinese Holstein cows were randomly divided into four groups, and each was offered a basal diet supplemented with 0, 1.5, 3.0 or 4.5 mg rutin/kg of diet. The milk yield of the cows receiving 3.0 and 4.5 mg rutin/kg was higher than that of the control group, and the milk yield was increased by 10.06% and 3.37% (p < 0.05). On the basis of that finding, the cows supplemented with 0 or 3.0 mg rutin/kg of diet were used to investigate the effect of rutin supplementation on blood metabolites and hormone levels. Compared with the control group, the serum blood urea nitrogen (BUN) concentration of the 3.0 mg rutin/kg group is significantly decreased (p < 0.05). In another trial, four adult cows with permanent rumen fistula and duodenal cannulae were attributed in a self‐control design to investigate the peak occurrence of rutin and quercetin in different parts of the gastrointestinal tract, ruminal fermentation and microbial population in dairy cows. The cows supplemented with 3.0 mg rutin/kg in the diet differed from the control period. Samples of rumen fluid, duodenal fluid and blood were collected at 1, 2, 3, 4, 5, 6, 7 and 8 h after morning feeding. Compared to the control group, the pH, ammonia nitrogen concentration, number and protein content of rumen protozoa and blood urea nitrogen were lower, but the concentration of total volatile fatty acid (TVFA), microbial crude protein (MCP) and serum lysozyme content were higher for the cows fed the rutin diets. The addition of 3.0 mg rutin/kg to diets for a long term tended to increase the milk yield and improve the metabolism and digestibility of the dairy cows.     

Effect of mixed maize-legume silages on milk quality and quantity from lactating smallholder dairy cows

The study investigated the effect of the following maize:legume (70:30) mixed crop silages: maize:cowpea, maize:velvet bean, and maize:lablab on milk production during the 2016 dry season. Using a 5?×?5 double Latin square design, five Holstein-Friesian crossbred cows in early lactation (30?±?15 days) and five Jersey crossbred cows in early lactation (25?±?10 days) were given the supplementary mixed crop silage diets at 0.5 kg/l of milk produced over 105 days. Commercial dairy meal and sole maize silage were used as positive and negative controls, respectively. Milk yield was significantly higher (P?< 0.05) in cows given the dairy meal compared to mixed crop silages; however, milk yield was also significantly higher (P?< 0.05) for cows given the three mixed crop silages compared to cows given sole maize silage. Cows given mixed crop silages produced milk of significantly higher protein content (P?< 0.05) than those given sole maize silage. There was no significant difference (P?> 0.05) in butterfat content of milk across all the dietary treatments. The dietary cost of producing 1 l of milk was highest at 0.31USD/l for cows given commercial dairy meal and lowest for cows given maize:velvet bean and maize:cowpea silage at 0.19USD/kg. The highest dietary gross margins of 68% were observed when cows were given maize:velvet mixed silage compared to commercial dairy meal (47%) and sole maize silage (57%). The 70:30 maize:legume mixed crop silages showed the capability to increase milk quantity and quality at very low production costs in smallholder dairy schemes.     

Effect of carbohydrate source and cottonseed meal level in the concentrate: IV. Feed intake, rumen fermentation and milk production in milking cows

Four early-lactation crossbred cows (82.5 % Holstein) were selected to investigate the effect of carbohydrate source and cottonseed meal level in the concentrate on rumen fermentation and milk production. Cows were randomly assigned to receive four dietary treatments according to a 2?×?2 factorial arrangement in a 4?×?4 Latin Square design. Factor A was carbohydrate source: cassava chip (CC) and CC + rice bran at a ratio 3:1 (CR3:1), and factor B was variation in the level of cottonseed meal (CM): low (LCM) and high (HCM) in isonitrogenous diets (180 g CP/kg DM). It was found that carbohydrate source did not affect feed intake, dry matter digestibility, rumen fermentation, microbial population, milk yield and composition, or economic return (P?>?0.05). However, cows fed with CC had a higher population of amylolytic bacteria than cows fed with CR3:1 (P?<?0.05). Cows fed with HCM had a higher total feed intake, milk yield and composition, and milk income when compared with cows fed on LCM although the concentrate and roughage intakes, dry matter digestibility, rumen fermentation, and microbial populations were similar between treatments (P?>?0.05). In addition, the carbohydrate source and cottonseed meal level interactions were not significant for any parameter. It could be concluded that cassava chip and high level of cottonseed meal could usefully be incorporated into concentrates for dairy cows without impacting on rumen fermentation or milk production.     

Effect of dietary inclusion of date seed (<Emphasis Type="Italic">Phoenix dactylifera</Emphasis> L.) on intake,digestibility, milk production,and milk fatty acid profile of Holstein dairy cows

The objective of this experiment was to investigate the influence of ground date seed (GDS) on intake, digestibility, and milk yield and milk fatty acid (FA) composition of lactating Holstein cows. The experimental design was a 4?×?4 replicated Latin square with eight lactating dairy cows with an average milk production of 35.5?±?1.5 kg and 75?±?5 days in milk (DIM). Dairy cows were fed one of the four treatments contained 0, 2, 4, and 6% of diet dry matter (DM) GDS in replacement of wheat bran. All diets contained the same amount of forages (alfalfa hay and corn silage). Dietary treatments had no effect on DM intake (DMI), total tract apparent digestibility, milk yield, and milk composition. Increasing GDS linearly decreased concentration of C13:0 and increased cis-9 C14:1 and trans-11 C18:1 (vaccenic acid) (P?<?0.05). A linear tendency for more C16:1 content in milk fat was observed with increasing GDS (P?=?0.06). Feeding GDS resulted in a linear decrease (P?<?0.01) in saturated FA (SFA) but increased milk fat monounsaturated FA (MUFA) and trans FA (TFA) (P?<?0.05). Therefore, low levels of GDS (up to 6%) in the diet of Holstein dairy cows can beneficially modify milk FA composition without any adverse effects on intake, digestibility, and milk yield.     

Effect of tannins and saponins in Samanea saman on rumen environment,milk yield and milk composition in lactating dairy cows

The objective of this study was to investigate the effects of tannins and saponins in Samanea saman on rumen fermentation, milk yield and milk composition in lactating dairy cows. Four multiparous early‐lactating dairy cows (Holstein‐Friesian cross‐bred, 75%) with an initial body weight (BW) of 405 ± 40 kg and 36 ± 8 day in milk were randomly assigned to receive dietary treatments according to a 4 × 4 Latin square design. The four dietary treatments were unsupplemented (control), supplemented with rain tree pod (S. saman) meal (RPM) at 60 g/kg, supplemented with palm oil (PO) at 20 g/kg, and supplemented with RPM at 60 g/kg and PO at 20 g/kg (RPO), of total dry matter (DM) intake. Cows were fed with concentrate diets at a ratio of concentrate to milk yield of 1:2, and chopped 30 g/kg of urea‐treated rice straw was fed ad libitum. The RPM contained condensed tannins and crude saponins at 88 and 141 g/kg of DM respectively. It was found that s upplementation with RPM and/or PO to dairy cows diets did not show negative effect on ruminal pH, blood urea nitrogen and milk urea nitrogen concentration (p > 0.05). However, supplementation with RPM resulted in lower ammonia nitrogen (NH₃‐N) concentration (p < 0.05). In addition, propionic acid and milk production increased while acetic acid, acetic to propionic ratio, methane production, methanogens and protozoal population decreased with RPM and/or PO supplementation. Furthermore, addition of PO and RPO in the diets increased milk fat while supplementation of RPM resulted in greater milk protein and Fibrobacter succinogenes numbers (p < 0.05). The population of Ruminococcus flavefaciens and Ruminococcus albus were not affected by any treatments. The findings on the present study showed that supplementation with RPM and RPO to diets of cows improved the rumen environment and increased milk yield, content of milk protein and milk fat.     

Effect of feeding dried distillers' grains with solubles on milk yield and milk composition of cows in mid‐lactation and digestibility in sheep

We evaluated the effect of three sources of dried distillers' grains with solubles (DDGS) in diets of mid‐lactating dairy cows on milk production and milk composition and on digestibility in sheep. DDGS from wheat, corn and barley (DDGS₁), wheat and corn (DDGS₂) and wheat (DDGS₃) were studied and compared with a rapeseed meal (RSM). RSM and DDGS were characterized through in situ crude protein (CP) degradability. Nutrient digestibility was determined in sheep. Twenty‐four multiparous cows were used in a 4 × 4 Latin square design with 28‐day periods. Treatments included total mixed rations containing as primary protein sources RSM (control), DDGS₁ (D1), DDGS₂ (D2) or DDGS₃ (D3). RSM contained less rapidly degradable CP (fraction a), more potentially degradable CP (fraction b) and more rumen undegradable CP (UDP) than the three DDGS. In vivo digestibility of RSM organic matter was similar to DDGS. Calculated net energy for lactation (NE_L) was lower for RSM (7.4 MJ/kg DM) than for DDGS, which averaged 7.7 MJ/kg DM. Cows' dry matter intake did not differ between diets (21.7 kg/day). Cows fed D1 yielded more milk than those fed D3 (31.7 vs. 30.4 kg/day); no differences were found between control and DDGS diets (31.3 vs. 31.1 kg/day). Energy‐corrected milk was similar among diets (31.2 kg/day). Diets affected neither milk fat concentration (4.0%) nor milk fat yield (1.24 kg/day). Milk protein yield of control (1.12 kg/day) was significantly higher than D3 (1.06 kg/day) but not different form D1 and D2 (1.08 kg/day each). Feeding DDGS significantly increased milk lactose concentration (4.91%) in relation to control (4.81%). DDGS can be a suitable feed in relation to RSM and can be fed up to 4 kg dry matter per day in rations of dairy cows in mid‐lactation. However, high variation of protein and energy values of DDGS should be considered when included in diets of dairy cows.     

Effects of Moringa oleifera silage on milk yield,nutrient digestibility and serum biochemical indexes of lactating dairy cows

This study investigated the effects of Moringa oleifera (MO) as a partial substitute of alfalfa hay on milk yield, nutrient apparent digestibility and serum biochemical indexes of dairy cows. MO was harvested at 120 days post‐seeding. Fresh MO was cut, mixed with chopped oat hay (425:575 on a DM basis), ensiled and stored for 60 days. Sixty healthy Holstein dairy cows were allocated to one of three groups: NM (no MO or control), LM (low MO; 25% alfalfa hay and 50% maize silage were replaced by MO silage) or HM (high MO; 50% alfalfa hay and 100% maize silage were replaced by MO silage). The feeding trial lasted 35 days. The LM and HM diets did not affect dry matter (DM) intake, milk yield or milk composition (lactose, milk fat, milk protein and somatic cell count). The apparent digestibility of DM and NDF was lower for HM group than NM group. Additionally, there were no significant differences in serum biochemical indexes between the LM and NM groups. The HM group had lower serum concentrations of total cholesterol, high‐density lipoprotein cholesterol, and low‐density lipoprotein cholesterol and higher serum concentrations of urea than the NM group. The partial replacement of alfalfa hay (≤50%) and maize silage with MO silage had no negative effects on milk yield, in vivo nutrient apparent digestibility or serum biochemical indexes of lactating cows.     

Milk production and composition,food consumption,and energy balance of postpartum crossbred Holstein-Gir dairy cows fed two diets of different energy levels

The objective of this study was to evaluate the production, consumption, and energy balance parameters of primiparous 3/4 and 7/8 Holstein × Gir (HG) dairy cows fed two diets of differing energy levels during the postpartum period. At the beginning of the study, 28 days prepartum, the average weight of both genetic groups was 498?±?12 kg and body condition score (BCS) was 3.5?±?0.05. At the end of the study, 61 days postpartum, the 3/4 HG cows had higher weight and body condition scores than the 7/8 HG (456?±?8 and 429?±?8 kg and 3.13?±?0.03 and 2.94?±?0.03 BCS for 3/4 HG and 7/8 HG, respectively). Milk from cows fed the high-energy diet had higher percentages of fat, protein, lactose, and total dry extract than cows fed the low-energy diet. Cows fed the high-energy diet had higher net energy intake (95.3?±?1.9 vs. 88.1?±?2.1 MJ/day) and higher energy balance (3.64?±?2.13 vs ??6.02?±?2.30 MJ/day). The 3/4 HG cows displayed higher energy for maintenance (33.1?±?0.4 MJ/day) than the 7/8 HG (31.5?±?0.5 MJ /day). In conclusion, although the primiparous 3/4 HG were heavier than the 7/8 HG and had a higher body condition score, no differences in milk produced up to 60 days postpartum were observed. The higher energy diet during the postpartum period increased energy balance, resulting in higher production of milk fat, protein, and lactose.

     

Performance of lactating dairy cows fed a diet based on treated rice straw and supplemented with pelleted sweet potato vines

The purpose of this study was to evaluate the effects of sweet potato vine pellet (SWEPP) in concentrate diets on nutrient digestibility and rumen ecology in lactating dairy cows fed on urea-treated rice straw. Three multiparous Holstein crossbred cows in mid-lactation were randomly assigned according to a 3?×?3 Latin square design, and the treatments were as follows: T1 = control (no supplementation), T2 = supplementation of sweet potato vine pellet with 50 g/kg urea (SWEPP I) at 300 g/head/day, and T3 = supplementation of sweet potato pellet with 100 g/kg urea (SWEPP II) at 300 g/head/day, in concentrate diets, respectively. The result revealed that supplementation of SWEPP did not affect feed intake, ruminal pH, and blood urea nitrogen (P?>?0.05). However, apparent digestibilities of organic matter, crude protein, and neutral detergent fiber were higher in SWEPP II than those in others. Furthermore, ruminal ammonia nitrogen (NH₃-N) and milk yield were significantly higher (P?<?0.05) in animals fed with SWEPP II than those fed with SWEPP I and control, respectively. In addition, there were no differences in purine derivatives and microbial nitrogen supply among all the treatments. Based on this study, it could be concluded that SWEPP is a good source of supplement which resulted in significant improvement in apparent digestibility, rumen fermentation, and milk yield in lactating dairy cows fed on urea-treated rice straw.     

Milk production performance of Friesian-Holstein cows fed diets containing Medicago sativa, Centrosema pubescens, or groundnut haulms (Arachis hypogaea)

To investigate the effect of feeding dairy cows diets containing lucerne hay, centrosema hay, and groundnut haulms (crop residue) on dry matter intake (DMI), milk yield, and milk composition, nine multiparous Friesian-Holstein cows in their mid-lactation stage were used in a 3?×?3 crossover design replicated three times. Dairy cows fed lucerne hay had significantly (p?<?0.001) higher DMI than dairy cows fed centrosema hay. DMI for cows fed groundnut haulms and lucerne hay was not significantly different. Daily milk yield for dairy cows fed diet containing lucerne hay was significantly (p?<?0.01) higher than that for dairy cows fed diets containing groundnut haulms or centrosema hay. Milk composition and body condition scores of the cows were not significantly affected by either lucerne hay, groundnut haulms, or centrosema hay. Overall, the results in this study indicated that feeding dairy cows diets containing lucerne hay increased milk yield.     

Effects of a Brown‐midrib corn hybrid on nutrient digestibility in wethers and on dry matter intake,performance, rumen and blood variables in dairy cows

The aim of the present trials was to determine the effect of an experimental Brown‐midrib (Bm) corn hybrid in relation to a commercial corn hybrid (Con) on digestibility in wethers and on dry matter intake (DMI), milk yield and milk composition in dairy cows. Digestibility of crude fibre (CF), neutral detergent fibre (NDFom) and acid detergent fibre (ADFom) were higher for Bm (CF Con: 57.8%; Bm: 67.2%; NDFom Con: 56.8%; Bm: 64.8%; ADFom Con: 52.0%; Bm: 63.9%), but concentration of net energy for lactation did not differ (Con: 6.4 MJ/kg DM; Bm: 6.3 MJ/kg DM). A total of 64 lactating German Holstein cows were assigned to one of the two dietary treatments Con or Bm according to milk yield, lactation number, days in milk and live weight. In Trial 1, cows were fed a total mixed ration consisting of 50% corn silage (Con or Bm) and 50% concentrate on dry matter (DM) basis. In Trial 2, the same animals were fed the respective silage for ad libitum intake and 5.3 kg of concentrate DM per animal per day. In Trial 1, DMI and milk‐fat content were decreased significantly for the Bm‐treatment (DMI Con: 22.5 kg/day; Bm: 21.5 kg/day; milk fat Con: 3.8%; Bm: 3.3%). In Trial 2, milk yield and fat‐corrected milk (FCM) were increased significantly, whereas milk‐fat% was decreased significantly (milk yield Con: 25.8 kg/day; Bm: 29.4 kg/day; FCM Con: 27.2 kg/day; Bm: 29.6 kg/day; fat Con: 4.4%; Bm: 4.0%). Diets did not influence ruminal pH or temperature. Diets, furthermore, did not influence rumination in either trial. Additional research on digestibility and rumen fermentation should, however, be carried out using dairy cows at respective intake levels as trials with wethers cannot be transferred to high‐yielding ad libitum fed cows.     

Development of enteric methane emission factors for Holstein-Friesian and Norwegian first lactation cows

Abstract

The objectives were to accurately quantify enteric methane (CH₄) emissions for first lactation dairy cows and to use these data to develop CH₄ prediction equations. Calorimeter measurements and production data were used to calculate CH₄ emissions for Holstein-Friesian (HF, n?=?32) and Norwegian (n?=?32) first lactation cows during a 305-d lactation period. Methane outputs were similar between HF and Norwegian (123 vs. 126?kg/305 d) when offered high-concentrate diets, but HF produced more CH₄ (P?<?0.05) than Norwegian (105 vs. 98?kg/305 d) when given low-concentrate diets. The HF offered high-concentrate diets had a lower (P?<?.05) CH₄ emission per energy-corrected milk yield (16.3?g/kg) than the other three treatments (19.7–20.4?g/kg). These data were then used to develop CH₄ prediction equations, which provide an alternative approach to estimate enteric CH₄ emissions for HF and Norwegian first lactation dairy cows.     

Feeding <Emphasis Type="Italic">Moringa oleifera</Emphasis> fresh or ensiled to dairy cows—effects on milk yield and milk flavor

Moringa oleifera, either fresh or ensiled, was compared with Elephant grass as a main feedstuff for dairy cows. To test the effects feed had on milk yield, milk composition, ration digestibility, and the organoleptic characteristics of milk, six lactating dairy cows were used in a Changeover 3 × 3 Latin Square experiment, replicated twice. With equal intake of metabolizable energy the intake of protein and fiber differed (p < 0.001) between all diets where fresh Moringa had the highest and the Elephant grass diet had the lowest intake. Compared with the control diet, ensiled Moringa had higher digestibility (P < 0.05) of both protein and fiber. With the exception of DM digestibility, no digestibility differences were found between fresh Moringa and Moringa silage treatments. Milk yield did not differ between any of the treatments and averaged 13.7 kg cow day⁻¹. Milk composition was similar among all treatments. Milk from the fresh Moringa treatment, however, had a grassy flavor and aroma, significantly different from the other two treatments, even though it was normal in color and appearance. No organoleptic differences were found between milk from the control treatment and the Moringa silage treatment. The conclusion is that Moringa silage can be fed to dairy cows in large quantities to produce the same quantity and quality of milk as traditional diets.     

Substitution of fresh forage ramie for alfalfa hay in diets affects production performance,milk composition,and serum parameters of dairy cows

We hypothesized that ramie, Boehmeria nivea (a nettle native to Asia), can be used as a high-quality forage to replace alfalfa hay in diets of dairy cows. Accordingly, we aimed to examine the effects of substituting fresh forage ramie for alfalfa (Medicago sativa) hay on production performance, milk composition, and serum parameters of dairy cows. Thirty-two Holstein cows (body weight (BW)?=?590?±?50.6 kg) were randomly divided into four groups of eight cows. The experimental period lasted 10 weeks. The dietary treatments consisted of four proportions of fresh forage ramie (0, 33, 67, and 100%) as a substitute for alfalfa hay (designated as CON, FR33, FR67, and FR100, respectively). On days 69 and 70 of the experimental period, milk and blood samples were collected for analysis. We found no significant differences in the milk yield and milk quality (milk protein percentage, milk fat percentage, and milk lactose percentage) between the treatments. We did find that forage ramie significantly reduced dry matter intake (DMI) and 4% fat-corrected milk (FCM) yield. Meanwhile, no significant differences were detected in serum parameters between the treatments, with the exception of triglyceride (TG) and alanine aminotransferase (ALT). In conclusion, our data indicate that alfalfa hay can be replaced with forage ramie in the diet of Holstein cows in the milk lactation stage, with no negative effects on milk quality and blood parameters.

     

饲喂高淀粉饲粮时不同瘤胃降解淀粉水平对奶牛泌乳性能、营养物质表观消化率和氮平衡的影响

本试验旨在研究饲喂高淀粉饲粮时不同瘤胃降解淀粉水平对奶牛泌乳性能、营养物质表观消化率和氮平衡的影响。选用10头荷斯坦经产奶牛[平均泌乳天数为(214±38)d,平均乳产量为(26.2±2.4)kg/d,平均体重为(727±65)kg]作为试验动物,随机分成2组,每组5头。试验设计2种不同瘤胃降解淀粉水平的试验饲粮,分别为瘤胃降解淀粉水平为62.3%(占总淀粉的百分比)的低瘤胃降解淀粉水平饲粮(L-RDS)和瘤胃降解淀粉水平为72.1%(占总淀粉的百分比)的高瘤胃降解淀粉水平饲粮(H-RDS)。采用交叉试验设计,试验分为2期,过渡期7 d,每期试验21 d,其中适应期14 d,采样期7 d。结果显示:1)相比L-RDS组,H-RDS组有机物和淀粉的表观消化率显著升高(P0.05),中性洗涤纤维和酸性洗涤纤维的表观消化率显著降低(P0.05),干物质表观消化率有升高趋势(P=0.07),蛋白质表观消化率无显著差异(P0.05)。2)相比L-RDS组,H-RDS组尿素氮及它们占摄入氮比例有降低趋势(P=0.09),摄入氮、乳氮、粪氮、尿氮和沉积氮及它们占摄入氮比例无显著变化(P0.05),尿中总嘌呤衍生物排出量和微生物蛋白产量亦无显著变化(P0.05)。3)饲粮瘤胃降解淀粉水平对奶牛干物质采食量、乳产量和乳成分均无显著影响(P0.05)。综合以上结果可知,饲喂高淀粉饲粮时不同瘤胃降解淀粉水平影响饲粮营养物质的表观消化率,对泌乳性能和氮平衡无显著影响。     

Oats (Avena strigosa) as winter forage for dairy cows in Vietnam: an on-farm study

In North Vietnam, during winter, alternative forage resources are needed to balance the feed ration of dairy cows. The objective of this study was to investigate the effect of oat forage as a component of traditional winter roughage diets on feed intake, milk production and feeding cost in dairy cows. The study was conducted on-farm using 24 mid-lactation Holstein–Friesian cows. The feeding experiment consisted of two successive periods and two dietary treatments per period. Traditional basal diets included fresh tropical grasses, maize silage and hay. The oat forage had no effect on the dry matter intake of the basal diet, but the total crude protein intake was higher in cows fed with oat diets than in those fed with control diets. The yield of butterfat-corrected milk (FCM) was not significantly different between diets during period 1, but there was a trend (P?=?0.078) of higher FCM yields in cows fed with the oat diet compared to those with control diet during period 2 (17.3 vs. 16.3 kg/day). The decline rate in milk yield was significantly higher (P?<?0.001) in cows fed with control diets than in those fed with oat diets in both experimental periods. The total feeding cost of cows fed with oat diets was on average 12 % lower than those fed with control diets (P?<?0.01). So, the oat forage is an important winter resource for cows in North Vietnam allowing higher milk yield whilst reducing feeding cost, compared to traditional roughage diets.     

Effect of partly replacing cottonseed cake with Mucuna spp. (var. Ghana) hay on feed intake and digestibility, milk yield and milk composition of zebu cows

The effect of partly replacing cottonseed cake with Mucuna hay (Mucuna spp. var. Ghana) on feed intake, digestibility and milk production of dairy cows was studied using six Zebu cows randomly assigned to three dietary treatments in a replicated Latin square design. All cows were fed hay from natural pastures ad libitum and 1.1 kg molasses as a basal diet, which was supplemented with: (1) 2 kg cottonseed cake (control diet), (2) 1.5 kg cottonseed cake and 1.2 kg Mucuna hay (low Mucuna, LM), and (3) 1.0 kg cottonseed cake and 3.3 kg Mucuna hay (high Mucuna, HM). Dry matter (DM) and crude protein (CP) intake were similar for all the diets. The addition of Mucuna significantly increased DM and organic matter digestibility, whereas CP, acid detergent fibre and neutral detergent fibre digestibility were similar among the diets. The treatments had no effect on daily milk yield (3.38, 3.43 and 3.38 kg milk) or milk composition (41.1, 43.7 and 42.7 g fat/kg milk; 35.1, 36.4 and 35.9 g protein/kg milk; and 46.1, 45.8 and 45.3 g lactose/kg milk, respectively, for cows fed control, LM and HM diets). The treatments had no significant effect on live weight changes. The results showed that replacing 50% of the cottonseed cake with Mucuna hay had no negative effects on feed intake and digestibility, milk yield or milk composition.     

Starch levels on performance,milk composition and energy balance of lactating dairy cows

The objective of this experiment was to evaluate the effects of starch levels in diets with the replacement of citrus pulp for corn on milk yield, milk composition, and energy balance of lactating dairy cows. Twenty-eight multiparous Holstein cows were used in seven 4?×?4 Latin squares conducted concurrently, and each experimental period consisted of 20 days (16 days for adaptation and 4 days for sampling). The experimental treatments comprised four starch levels: 15, 20, 25, and 30 % in the diet. The dry matter intake increased linearly with increasing starch levels. The milk yield and 3.5 % fat-corrected milk yield showed quadratic response to increasing starch levels. The milk protein content and milk total solids content responded linearly to increasing starch levels. The feed efficiency, milk lactose content, milk urea nitrogen, plasma urea nitrogen, and plasma glucose concentration were not affected by starch levels. The estimated net energy for lactation (NE_L) intake increased linearly as the starch level was raised. Although the milk NE_L output per kilogram of milk was not affected by starch, the milk NE_L output daily responded quadratically to starch levels. In addition, the NE_L in body weight gain also responded quadratically to increasing starch levels. The efficiency of energy use for milk yield and the NE_L efficiency for production also responded quadratically to increasing starch levels. Diets for mid-lactating dairy cows producing around 30 kg/day of milk should be formulated to provide around 25 % starch to optimize performance.