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.

     

饲粮粗蛋白质水平对泌乳水牛产奶量及氮代谢的影响

本试验旨在研究饲粮粗蛋白质水平对泌乳水牛产奶量及氮代谢的影响。试验采用４×４拉丁方试验设计,选用 １６头体况良好、上期泌乳量相近、产犊胎次 ２～３胎、健康的泌乳前期水牛,随机分为４组,进行动物饲养试验和消化代谢试验。将４组泌乳水牛随机分配到４个梯度的饲粮粗蛋白质水平组,即 １６．０％、１５．２％、１４．４％、１３．６％ ４个组,每组 ４头,进行 ４期饲养试验,每期 ２１ｄ,共 ８４ｄ。按照 ４×４拉丁方设计给各期各组泌乳水牛饲喂不同粗蛋白质水平的饲粮,每期试验预试期 ７ｄ。在第 ２期和第 ４期饲养试验的最后 ４ｄ开展 ２期氮消化代谢试验。结果表明,总采食氮、可消化氮、乳氮／进食氮以及氮表观消化率在部分组间差异显著（Ｐ＜０．０５）;乳氮、粪氮、尿氮在各组间差异不显著（Ｐ＞０．０５）。饲喂不同粗蛋白质水平饲粮对水牛产奶量、乳蛋白率、乳脂率、乳非脂固形物率和乳糖率均无显著影响（Ｐ＞０．０５）。血清总蛋白和尿素氮含量各组间差异不显著（Ｐ＞０．０５）。以试验期间进食氮水平（ｇ／ｄ）为横坐标（ｘ）,标准乳产量（ｋｇ／ｄ）为纵坐标（ｙ）,获得进食氮水平与标准乳产量的二次曲线关系,即 ｙ＝－０．００１６ｘ２＋０．９５５６ｘ－１２９．９１。由此可见,饲粮粗蛋白质水平对泌乳水牛生产性能及血液生化指标影响不显著,根据进食氮水平与标准乳产量的二次曲线关系可得,当进食氮水平为 ２９８．６２５ｇ／ｄ时,得到水牛标准乳产量最大值为 １２．７７３ｋｇ／ｄ。     

ORIGINAL ARTICLE: Effects of dietary glucose inclusion on reproductive performance,milk compositions and blood profiles in lactating sows

Twenty‐four multiparous sows were used to investigate the effects of dietary glucose inclusion on reproductive performance, milk compositions, blood metabolites and hormones during lactation. The sows were randomly assigned to four treatments and each treatment had six replicates (sows). The diets were added with 0%, 1%, 3% or 5% glucose at the expense of corn and fed to sows for 24 days. The loss of backfat thickness during lactation was quadratically decreased (p = 0.008) and the wean‐to‐oestrus interval was shortened (linear, p = 0.013; quadratic, p = 0.009) with increasing levels of dietary glucose supplementation. The reproductive performance was not affected (p > 0.05) by different dietary glucose contents. Increased concentrations of total solid and fat in milk were noted (p < 0.05), whereas there was no difference on colostrum compositions. With increasing levels of dietary glucose inclusion, the concentrations of blood urea nitrogen (p = 0.004) and glucose (p = 0.029) were linearly increased at weaning. The concentrations of insulin were increased at post‐farrowing (linear, p = 0.027; quadratic p = 0.013) and weaning (linear, p = 0.029; quadratic, p = 0.017), respectively. Furthermore, the pulses of insulin and FSH at weaning were linearly (p = 0.049) and quadratically (p = 0.015) increased with the increasing levels of dietary glucose inclusion. In conclusion, this study indicated that inclusion of 3% glucose in lactating diet could reduce backfat loss, increase milk fat and have no negative effect on reproductive performance in multiparous sows.     

Ruminal dynamics of ad libitum feeding in buffalo bulls receiving different level of rumen degradable protein

Four ruminally cannulated Nili-Ravi buffalo bulls were used in a 4 × 4 Latin Square Design to determine the influence of varying level of ruminally degradable protein (RDP) on dry matter intake (DMI), ruminal characteristics, digestibility, blood pH, blood urea nitrogen (BUN) and nitrogen (N) balance. Four isonitrogenous and isocaloric diets were formulated. The C diet contained 50% RDP while medium, high and very high RDP diets had 66, 82 and 100% RDP of the total crude protein (CP) and were denoted as MRDP, HRDP and VHRDP, respectively. The bulls were fed ad libitum. Nutrients intake decreased linearly with increasing the RDP proportion of total dietary CP. A quadratic effect of RDP on ruminal pH was noticed with increasing level of RDP with quadratic maxima at 66% RDP diet. Increasing level of dietary RDP also had a quadratic effect on total bacterial and protozoal count with maximum microbial count at 82% RDP diet. Increasing dietary RDP resulted in linear increase in DM digestibility. However, neutral detergent fiber digestibility was decreased linearly with increasing the level of dietary RDP. A linear increase in ruminal NH₃–N and BUN was noticed due to increasing level of dietary RDP. Higher positive N balance was noticed in bulls fed C diet compared to those fed MRDP, HRDP and VHRDP diets. The findings of this study indicated that buffalo bulls can effectively utilize 13.12% RDP of DM without any adverse effect on rumen and blood parameters.     

饲粮粗蛋白质水平对中国荷斯坦奶牛产奶性能、氮利用及血液激素的影响

本试验旨在研究饲粮粗蛋白质（ＣＰ）水平对中国荷斯坦奶牛产奶性能、氮利用及血液激素的影响。采用重复 ４×４拉丁方设计,８头经产中国荷斯坦奶牛随机分为 ４个处理。４个处理的饲粮 ＣＰ水平分别为 １２．５６％、１３．９６％、１５．５３％和 １６．９３％。试验分为 ４个周期,每个周期１８ｄ。在 ４ｄ收集期内,全量收集粪、尿,每天测量产奶量、乳成分和干物质摄入量（ＤＭＩ）,并在收集期最后 １ｄ采集血样。结果表明：４个饲粮处理的 ＤＭＩ基本相同（Ｐ＞０．０５）;饲粮 ＣＰ水平１２．５６％的产奶量和能量校正奶（ＥＣＭ）明显低于饲粮 ＣＰ水平 １３．９６％至 １６．９３％（Ｐ＜０．０５）,饲粮 ＣＰ水平 １３．９６％至 １６．９３％的产奶量和 ＥＣＭ 基本相同,其中饲粮 ＣＰ水平 １３．９６％和１６．９３％的产奶量分别为２８．１８和２８．７２ｋｇ／ｄ,ＥＣＭ分别为３２．６４和３２．０４ｋｇ／ｄ;乳成分中仅乳蛋白率随着饲粮 ＣＰ水平增加而提高（Ｐ＜０．０５）;饲粮 ＣＰ水平 １２．５６％和 １３．９６％的乳氮效率明显高于饲粮 ＣＰ水平 １５．５３％和 １６．９３％（Ｐ＜０．０５或 Ｐ＜０．０１）;随着饲粮 ＣＰ水平的提高,尿氮排出量不断增加,乳氮排出量也缓慢上涨,体内氮沉积显著增加（Ｐ＜０．０５或 Ｐ＜０．０１）,只有饲粮 ＣＰ水平 １６．９３％的粪氮排出量明显增加（Ｐ＜０．０５）;饲粮 ＣＰ水平 １２．５６％的血液瘦素浓度最高（Ｐ＜０．０５）,催乳素（ＰＲＬ）、生长激素（ＧＨ）、胰岛素样生长因子 １（ＩＧＦ １）、血糖、非酯化脂肪酸（ＮＥＦＡ）和 β－羟丁酸（ＢＨＢＡ）浓度较高;而饲粮 ＣＰ水平 １６．９３％的血浆尿素氮（ＰＵＮ）浓度最高（Ｐ＜０．０１）,胰岛素和 ＧＨ浓度较高,ＩＧＦ １浓度较低。由此可见,饲粮 ＣＰ水平１３．９６％适合中国荷斯坦奶牛产奶量２８ｋｇ／ｄ或 ＥＣＭ３２ｋｇ／ｄ的泌乳性能、氮利用和内分泌调节。     

Effect of dietary protein on intake,nutrients utilization,nitrogen balance,blood metabolites,growth and puberty in growing Bhadawari buffalo (Bubalus bubalis) heifers

Fifteen Bhadawari buffalo heifers of 207?±?9.78 kg mean body weight were randomly distributed into three dietary groups to evaluate the effect of protein level on nutrient utilization, nitrogen (N) balance, growth rate, blood metabolites, and puberty. All animals were offered wheat straw-berseem diets supplemented with concentrate mixtures of similar energy (2.7 Mcal/kg) and different protein levels (14.3–22 %). Animals of standard-protein group (SPG) were offered protein and energy as per requirement, while animals of low-protein group (LPG) and high-protein group (HPG) were fed 20 % less and 20 % more protein, respectively, than SPG. Feed dry matter (DM) and metabolizable energy (ME) intake (% body wt. and g/kg w^0.75) were similar for all three diets; however, the crude protein (CP) and digestible crude protein (DCP) intake on percent body weight and per kilogram metabolic weight was higher (P?<?0.05) in HPG than in SPG or LPG. Digestibility of CP, cellulose, and hemicellulose was higher (P?<?0.05) in HPG versus LPG. Fecal N excretion was similar, while urinary N excretion was highest (P?<?0.05) in HPG (74.83 g/day) compared with SPG (50.03 g/day) and LPG (47.88 g/day), which resulted in lower N retention in HPG than in the other dietary groups. Level of dietary N had no effect on blood metabolites viz. glucose, urea, and N. Digestible energy (DE) and ME contents of diets were identical, while DCP contents were higher (P?<?0.05) in HPG than in LPG. Feed and nutrient (CP and ME) conversion efficiency to produce a unit kilogram weight gain was identical among the dietary groups. Dietary protein level had no effect on the heifer’s weight and age at puberty. The mean growth rate of heifers at 240 days was higher (P?>?0.05) in SPG (330.8 g/day) than in LPG (296.7 g/day), while the animals gained more weight in January to March months and the lowest weight in May to July months. Protein level had no effect on conception rate of heifers. Results revealed that 20 % higher or less protein than the ICAR requirement had no significant (P?>?0.05) on feed intake, nutrient conversion efficiency for weight gain, heifer growth, and puberty; however, 20 % more protein increased urinary N loss.

     

Growth and body composition of dairy calves fed milk replacers containing different amounts of protein at two feeding rates

Previous research has demonstrated that increasing the CP concentration from 16 to 26% in milk replacers fed to male preruminant dairy calves at 1.5% of BW (DM basis) daily resulted in increased ADG, G:F, and deposition of lean tissue. However, the effects of dietary CP would be expected to vary depending on ME intake. Here, male Holstein calves < 1 wk old were used to determine the effects of feeding rate and CP concentration of isocaloric, whey protein-based milk replacers on growth and body composition. After a 2-wk standardization period, calves were assigned randomly to an initial baseline group or to treatments in a 2 x 4 factorial arrangement of feeding rate (1.25 or 1.75% of BW daily, DM basis) and milk replacer CP concentration (14, 18, 22, or 26% of DM). No starter was offered, but calves had free access to water. After a 5-wk feeding period, calves were slaughtered and body composition was determined. Increasing the feeding rate increased (P < 0.05) ADG, G:F, empty-body gains of chemical components and energy, the percentage of fat in empty BW gain and in the final empty body, and concentrations of IGF-I and insulin in plasma. Increasing the feeding rate decreased (P < 0.01) percentages of water and protein in the empty body and decreased urea N in plasma. Increasing dietary CP concentration linearly increased (P < 0.05) ADG, body length, heart girth, and gains of water and protein but linearly decreased (P < 0.05) fat gain. As dietary CP increased, fat content in empty body gain decreased, and water and protein increased. Increasing CP concentration increased (quadratic, P < 0.02) G:F, with greatest efficiencies for calves fed 22% CP. Gross energetic efficiency (retained energy:intake energy) was greater (P < 0.05) for calves fed at 1.75% of BW daily. Efficiency of dietary protein use for protein gain was greater for calves fed at 1.75% of BW daily but was not affected by dietary CP. The ratio of protein gain to apparently digestible protein intake above maintenance decreased as dietary CP increased. Interactions (P < 0.05) of feeding rate and CP concentration for gains of water and protein indicated that when dietary CP was 26% the ME supply limited protein use by calves fed at 1.25% of BW daily. Body composition of preruminant calves can be markedly altered by manipulating the protein to energy ratio in milk replacers. These dietary effects on body composition and growth are not predicted by current NRC standards.     

Mesquite pod meal as an additive increases milk total solids,lactose, fat and protein content in dairy cows

The objective was to evaluate the intake, digestibility, milk yield and composition of cows fed mesquite pod meal (MPM). Five crossbred dairy cows, with an average body weight of 450?±?5 kg and producing 10?±?1 kg of milk/day were distributed in a 5?×?5 Latin square arrangement with five periods of 20 days each, comprised of 15 days for adaptation to the experimental diets (T1?=?0%, T2?=?1.5%, T3?=?3.0%, T4?=?4.5% and T5?=?6.0% MPM) and 5 days for data collection. Variables were assessed by analysis of variance and regression at P?<?0.01 and P?<?0.05 of significance, using the Student’s test. Animals were kept on pastures and the concentrates were provided at 6 kg/animal divided in two meals per day. The inclusion of 3.0% mesquite pod meal did not affect the intake, digestibility of nutrients and milk yield, but it changed milk composition. The dietary inclusion of 3.0% mesquite pod meal as a palatability enhancer increases the percentage of milk solids, lactose, fat and protein. Therefore, mesquite pod meal can be included in diets for dairy cows to improve the nutritive value of milk.

     

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 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.     

Effects of dietary nonprotein nitrogen on performance, digestibility, ruminal characteristics, and microbial efficiency in crossbred steers

Two trials were conducted to evaluate the effects of dietary NPN levels on animal performance, diet digestibility, ruminal characteristics, and microbial efficiency. Experiment 1 was conducted with 24 Holstein x Nellore crossbred steers (350 +/- 20 kg of BW) distributed in 6 blocks to evaluate intake and digestibility of nutrients and performance. The diets consisted of 70% corn silage and 30% concentrate (DM basis) and were formulated to contain 12.5% CP (DM basis). Treatments consisted of 0, 15.5, 31, and 46.5% of dietary N as NPN. There were no treatment differences in the daily intakes of DM (P = 0.47), OM (P = 0.60), CP (P = 0.24), nonfiber carbohydrates (NFC; P = 0.74), or TDN (P = 0.63); however, NDF intake decreased linearly as NPN increased (P = 0.02). Additionally, no effects of NPN were observed on apparent total tract digestibility of DM (P = 0.50), OM (P = 0.53), NDF (P = 0.63), or NFC (P = 0.44). The apparent total tract digestibility of CP increased linearly (P = 0.01), but ADG (1.14 kg/d) was not influenced (P = 0.96) as NPN increased. In Exp. 2, 4 ruminally and abomasally cannulated steers (300 +/- 55 kg of BW) were fed the same diet used in Exp. 1 to evaluate the effects of NPN levels on intake and digestibility of nutrients, ruminal characteristics, and microbial efficiency. There were no differences in the daily intakes of DM (P = 0.22), OM (P = 0.17), CP (P = 0.31), NDF (P = 0.29), or TDN (P = 0.49). However, NFC intake increased linearly (P = 0.02), and there was a quadratic effect (P = 0.01) on intake of ether extract as NPN increased. Ruminal digestibility of CP increased linearly (P = 0.01) with the increase of dietary NPN. There were no differences (P >or= 0.28) in microbial protein synthesis and microbial efficiency among the treatments. The results of these trials suggest that dietary NPN levels (up to 46.5% of total N) can be fed to crossbred steers receiving corn silage-based diets without affecting their growth performance or ruminal protein synthesis.     

Sulfate supplementation of alpine goats: effects on milk yield and composition, metabolites, nutrient digestibilities, and acid-base balance.

Effects of sulfate supplementation on milk yield and composition, ruminal and blood metabolites, acid-base status, and nutrient digestibilities were determined using 30 multiparous, lactating Alpine does. Goats were fed isonitrogenous diets containing .16 (basal), .26, or .36% S (DM basis) during a 13-wk lactation trial that coincided with wk 3 to 15 of lactation. During wk 16 to 17, four does from each treatment were placed in a metabolism crate to measure nutrient digestibility and balance. Feed intake, yield of 4% fat-corrected milk, and milk S content were not affected by added S, but the goats fed the .26% S diet had a trend of higher persistency of lactation (P < .20). During wk 10 and 15 of lactation, milk solids-not-fat percentage was higher (P < .10) for does fed the .26% S diet. Sulfur supplementation resulted in quadratic decreases in ruminal ammonia N (P < .05) in wk 15 and in plasma urea N in wk 10 and 15 (P < .05) but in linear increases (P < .05) in ruminal protein S concentrations throughout the experiment. Added S had little effect on blood acid-base status. Apparent digestibilities of DM, OM, ash, ADF, and GE were increased linearly (P < .10) by added S. The milk N:S ratio remained constant. Increasing S from .16 to .26% of diet DM was beneficial to lactating Alpine goats during early lactation.     

Effect of propylene glycol and undegradable protein source on rumen fermentation, blood metabolism and milk production in lactating dairy cows

Eight lactating Holstein cows were divided into two groups ( n  = 4) and used in a double reversal trial with three periods of 14 days each, to evaluate diets containing propylene glycol (PG) and ruminally undegradable protein (RUP) blend on milk yield and composition, ruminal fermentation and blood metabolism. The control diet contained 20% chopped Sudangrass hay, 20% cubed alfalfa hay, 12% corn silage, and 48% of the respective concentrate mixtures (dry matter basis). The experimental diet (PG + RUP) partially replaced the concentrate mixture from the control diet with 1.4% PG and 2.1% RUP. Both diets contained about 16% crude protein and 71% total digestible nutrients. Dry matter intake was similar between the two diets. Daily production of milk, milk lactose and milk solids-not-fat increased by 9.0%, 11.3% and 9.3%, respectively ( P  < 0.1), for cows fed diets with PG + RUP; milk composition was unchanged. Although the concentration of ruminal total volatile fatty acids was unchanged, the proportion of propionic acid increased, and the proportion of acetic acid decreased with PG + RUP. The concentration of ruminal ammonia nitrogen and number of ciliate protozoa was not significantly affected by PG + RUP. The concentration of glucose in blood plasma increased, the concentration of urea nitrogen was unaffected, and the concentration of some essential free amino acids decreased with PG + RUP. It is suggested that these changes might be caused predominantly by PG, and the addition of PG may exert a favorable effect on milk production through increased metabolism.     

Growth,nutrient utilization,and body composition of dairy calves fed milk replacers containing different amounts of protein

Male Holstein calves < 1 wk of age were allowed a 2-wk adaptation period after purchase, and then were blocked by BW and assigned randomly within block to either a baseline slaughter group or one of four experimental groups (n = 8 to 9 per group). Treatments were isocaloric milk replacers (12.5% solids) fed at 12% of BW that contained 16.1, 18.5, 22.9, or 25.8% CP (DM basis) from whey protein sources. After a 6-wk feeding period, all calves were slaughtered and the weights and chemical composition of the viscera-free carcasses (VFC; including head, hide, feet, and tail) were determined. Gain of BW (0.38, 0.45, 0.56, and 0.62 kg/d) and gain:feed ratio (0.51, 0.59, 0.71, and 0.78) increased linearly (P < 0.001) as dietary CP increased; rate of change in body length, wither height, and heart girth also increased linearly (P < or = 0.05). Balance measurements conducted during wk 3 and 4 of the experimental period showed that both absorbed N (16.9, 20.0, 25.8, and 30.6 g/d) and retained N (7.6, 9.0, 13.2, and 15.6 g/d) increased linearly (P < 0.001) as dietary CP increased. Retained N as a percentage of absorbed N increased linearly (P < 0.01) as dietary CP increased (44.3, 44.7, 50.7, and 50.9%), whereas biological value was unaffected (71.1, 68.7, 69.5, and 67.3%; P = 0.26). Digestible energy and ME represented 94.5 and 89.7% of intake energy, respectively, and were not affected by dietary CP content. Plasma urea N concentration increased linearly (2.9, 3.3, 4.6, and 6.0 mg/dL) as dietary CP increased. Contents of water (68.2, 69.1, 70.2, and 70.5%; P < 0.001) and protein (19.6, 20.0, 20.0, and 20.2%; P < 0.10) in VFC increased linearly, whereas contents of fat (7.2, 6.2, 5.5, and 5.2%; P < 0.001) and ash (5.1, 5.2, 4.8, and 4.7%; P < 0.02) decreased linearly as dietary CP increased. Trends in visceral tissue composition were similar to those for VFC. The content of water in VFC tissue gain increased, whereas contents of fat and energy decreased, as dietary CP increased. Final VFC energy and gain of energy in VFC were not affected by dietary CP. At similar initial ME intakes, increasing dietary CP (i.e., increasing protein: energy) linearly increased ADG, gain:feed, N retention, and deposition of lean tissue in VFC, demonstrating that diet composition can markedly affect components of body growth in preruminant dairy calves.     

Metabolic and productive response to ruminal protein degradability in early lactation cows fed untreated or xylose‐treated soybean meal‐based diets

Effects of different dietary rumen undegradable (RUP) to degradable (RDP) protein ratios on ruminal nutrient degradation, feed intake, blood metabolites and milk production were determined in early lactation cows. Four multiparous (43 ± 5 days in milk) and four primiparous (40 ± 6 days in milk) tie‐stall‐housed Holstein cows were used in a duplicated 4 × 4 Latin square design with four 21‐day periods. Each period had 14‐day of adaptation and 7‐day of sampling. Diets contained on a dry matter (DM) basis, 23.3% alfalfa hay, 20% corn silage and 56.7% concentrate. Cows were first offered alfalfa hay at 7:00, 15:00 and 23:00 hours, and 30 min after each alfalfa hay delivery were offered a mixture of corn silage and concentrate. Treatments were diets with RUP:RDP ratios of (i) 5.2:11.6 (control), (ii) 6.1:10.6, (iii) 7.1:9.5 and (iv) 8.1:8.5, on a dietary DM% basis. Different RUP:RDP ratios were obtained by partial and total replacement of untreated soybean meal (SBM) with xylose‐treated SBM (XSBM). In situ study using three rumen‐cannulated non‐lactating cows showed that DM and crude protein (CP) of SBM had greater rapidly degradable fractions. The potentially degradable fractions were degraded more slowly in XSBM. Treatment cows produced greater milk, protein, lactose, solids‐non‐fat and total solids than control cows. Increasing RUP:RDP reduced blood urea linearly. Feed costs dropped at RUP:RDP ratios of 6.1:10.6 and 7.1:9.5, but not at 8.1:8.5, compared with the 5.2:11.6 ratio. Intake of DM and CP, rumen pH, blood glucose, albumin and total protein, faecal and urine pH, changes in body weight and body condition score, and milk lactose and solids‐non‐fat percentages did not differ among treatments. Results provide evidence that increasing dietary RUP:RDP ratio from 5.2:11.6 to 7.1:9.5 optimizes nitrogen metabolism and milk production and reduces feed costs in early lactation cows. Reduced blood urea suggests reprodutive benefits.     

Improving the nutritive value of wheat straw with urea and yeast culture for dry season feeding of dairy cows

The study evaluated the effects of feeding urea treated/supplemented wheat straw-based diets with addition of yeast culture (YC) as a dry season feed for dairy cows. Wheat straw diets with 3.6 % urea and 5.8 % molasses were formulated to upgrade nonprotein nitrogen levels and fibre degradation in the rumen. Yeast culture was included at 0 and 10 g/cow/day in mixer with commercial dairy meal to improve on fibre degradation and milk yield. Two experiments were conducted. Firstly, an in sacco dry matter degradability (DMD) trial with three steers in a completely randomized design (CRD) with a 3?×?2 factorial arrangement to determine the effects on intake and rumen degradation parameters. Secondly, feeding trial with 18 lactating cows in a 3?×?2 factorial arrangement at two levels of yeast culture (0 and 10 g/cow/day) and three types of urea interventions: No intervention (WS); addition of urea to straw at the time of feeding (USWS); and 7 days incubation of straw with urea (UTWS). Yeast cultures addition had no effect on rumen pH and NH₃-N, but urea intervention showed an effect on rumen pH with USWS being lowest (p?<?0.05). Both urea interventions and yeast culture addition had no effect (p?>?0.05) on dry matter intake, milk yield, and milk composition but they increased (p?<?0.05) propionate yields.     

饲粮蛋白质水平对冬毛生长期水貂生长性能、血清生化指标及毛皮质量的影响

本文旨在探讨饲粮蛋白质水平对水貂生长性能、营养物质消化吸收、毛皮品质和血清生化指标的影响.随机选取日龄体重相近的70只健康公水貂平均分至5组,饲喂5个蛋白质水平的饲粮(32%、28%、24%、20%和16%),每千克干物质中含蛋白质分别为326.4、284.7、249.3、203.9和172.8 g.试验组编号分别为P...     

Effects of replacing wheat bran by pistachio skins on feed intake,nutrient digestibility,milk yield,milk composition and blood metabolites of dairy Saanen goats

The objective of this study was to investigate the effect of pistachio skins (PiS) as a replacement of wheat bran on feed intake, nutrient digestibility, milk yield, milk composition and blood metabolites of dairy Saanen goats. Eight multiparous lactating Saanen goats (55 ± 7.2 days post‐partum, 45 ± 2 kg body weight) were randomly assigned to one of the four dietary treatments arranged in a replicated 4 × 4 Latin square design. The dietary treatments were 1) 0 g/kg PiS and 210 g/kg wheat bran in the TMR (0PiS), 2) 70 g/kg PiS and 140 g/kg wheat bran in the TMR (7PiS), 3) 140 g/kg PiS and 70 g/kg wheat bran in the TMR (14PiS) and 4) 210 g/kg PiS and 0 g/kg wheat bran in the TMR (21PiS). The trial consisted of four 21‐day periods, each composed of 14 days adaptation and 7 days data collection. Dry matter intake (p < 0.05) and crude protein digestibility (p < 0.01) increased linearly with increasing PiS proportions in the diet. Increasing the proportion of PiS in the diet caused a quadratic increase in apparent digestibility of dry matter (p < 0.05), and tended (p = 0.05) to increase quadratically organic matter, and ether extract digestibility. Replacing wheat bran with PiS in the diet had no effects on milk yield, whereas milk fat concentration increased linearly (p < 0.01) with increasing inclusion of PiS in the diet. As the dietary proportion of PiS increased, ruminal pH tended (p = 0.07) to increase linearly, whereas ammonia‐N concentration declined in the rumen. Plasma concentrations of glucose and BUN remained unaffected, whereas triglycerides (p < 0.05) and cholesterol (p < 0.01) concentrations increased linearly with increasing inclusion of PiS in the diet. It was concluded that PiS based on local ingredients can successfully replace wheat bran in diets of dairy goats without detrimental effects on feed intake, nutrient digestibility and milk production.     

Effects of feeding different dietary protein and energy levels on the performance of 12–15-month-old buffalo calves

The study investigated the performance response of different dietary protein and energy levels of Nili-Ravi buffalo calves. Sixty buffalo calves of 12–15 months of age and similar body weight (140 ± 14 kg) were divided in to 12 groups, five animals in each group, according to 4 × 3 factorial arrangements. Twelve rations were formulated containing four levels of crude protein (CP; 10.5%, 12.20%, 13.80%, and 15.55%) each with three levels (1.72, 2.11, and 2.5 Mcal/Kg) of metabolizable energy (ME). Experiment lasted for 100 days; first 10 days were given for dietary adaptation. Daily feed consumption in calves fed all experimental diets were statistically significant (p < 0.05) across all treatments. Higher feed intake was observed in buffalo calves fed diets containing 12.20% and 13.85% CP with 2.11 Mcal/kg ME. Results of dry matter (DM) digestion were significantly different (p < 0.05) across all treatments. There was a quadratic (p < 0.05) response of DM digestibility for levels of dietary protein while, curvilinear (p < 0.05) trend with respect to dietary energy levels. Daily weight gain of buffalo calves did not show any treatment effect. The outcome of the present study indicate that 12–15-month-old buffalo calves perform adequately well when fed on diets containing 12.2% CP and 2.10 ME Mcal/Kg.     

Feeding different dietary protein to energy ratios to Holstein heifers: effects on growth performance,blood metabolites and rumen fermentation parameters

Eighteen Chinese Holstein heifers average age 230 ± 14 days were allocated to 1 of 3 dietary crude protein (CP) to metabolizable energy (ME) ratios to examine the effects on growth performance, blood metabolites and rumen fermentation parameters with 90‐days experiment. Three different dietary CP:ME ratios were targeted based on the formulation of dietary CP contents of 10.85%, 12.78% and 14.63% on dry matter (DM) basis with similar ME contents (10.42 MJ/kg DM), which were categorized as low, medium and high dietary CP:ME ratios. The actual CP:ME ratios obtained in this study significantly increased from low to high CP:ME ratio groups with a value of 10.59, 11.83 and 13.38 g/MJ respectively. Elevated CP:ME ratios significantly increased CP intake (kg/day) and feed efficiency (FE) which was defined as dry matter intake as a proportion of average daily gain (ADG), whereas little difference was observed in body weight (kg), ADG (kg/day), DM intake (kg/day) and ME intake (MJ/day) among the three different CP:ME ratio groups. Increasing dietary CP to ME ratios significantly increased CP digestibility, whereas digestibility of DM and gross energy remained constant in the current experiment. Blood urea nitrogen and insulin‐like growth factor‐1 linearly increased with increasing dietary CP:ME ratios. There was significantly dietary treatment effect on rumen fermentation parameters including acetate, propionate, butyrate and total volatile fatty acids. Therefore, this study indicated that increasing dietary CP levels with similar energy content contributed to increased protein intake and its digestibility, as well as FE. Holstein heifers between 200 and 341 kg subjected to 13.38 dietary CP:ME ratio showed improved feed efficiency, nutrient digestibility, some blood metabolites and rumen fermentation characteristics for 0.90 kg/day rate of gain.