Effect of glyphosate contaminated feed on rumen fermentation parameters and in sacco degradation of grass hay and corn grain

Four rumen fistulated wethers were used to investigate the effect of glyphosate contaminated feed on rumen fermentation. The rations were based on corn silage, urea and a vitamin-mineral premix, either in the absence or presence of 0.77?g glyphosate per kg DM. Furthermore, rations were fed either with or without aromatic amino acid supplementation. During four periods of 28 days, sheep received each of the four dietary treatments according to a Latin square. After 14 days of adaptation rumen fermentation parameters (pH, ammonia, volatile fatty acids) were measured on day 15 over a five-hour period after the morning feeding. The remaining 13 days served for in sacco degradation studies with grass hay and corn grain. Ammonia (NH₃) and pH of rumen fluid were within the normal range for all dietary treatments (NH₃: 9.1 – 32.3?mmol·l^???1, pH: 6.2 – 6.7). Neither rumen fermentation parameters nor in sacco DM and NDF degradation of incubated feedstuffs were significantly affected by glyphosate, with or without aromatic amino acid supplementation. Kinetic profiles of the in sacco dry matter and NDF degradation of grass hay were almost identical for the dietary treatments.     

High-grain diet feeding altered the composition and functions of the rumen bacterial community and caused the damage to the laminar tissues of goats

In the current intensive production system, ruminants are often fed high-grain (HG) diets. However, this feeding pattern often causes rumen metabolic disorders and may further trigger laminitis, the exact mechanism is not clear. This study investigated the effect of HG diet feeding on fermentative and microbial changes in the rumen and on the expression of pro-inflammatory cytokines and matrix metalloproteinases (MMPs) in the lamellar tissue. In all, 12 male goats were fed a hay diet (0% grain; n=6) or an HG diet (56.5% grain; n=6). On day 50 of treatment, samples of blood, rumen content, and lamellar tissue of hooves of goats were collected. The data showed that compared with the hay group, HG-fed goats had lower (P<0.05) rumen pH but higher (P<0.05) total volatile fatty acids and lactate in the rumen and higher (P<0.05) lipopolysaccharide (LPS) levels in the rumen and blood. HG diet feeding altered the composition of rumen bacterial community, and correspondingly, the results suggested that their functions in the HG group were also altered. HG diet feeding increased (P<0.05) the expression of interleukin-1β, interleukin-6, tumour necrosis factor-α and MMP-2 mRNA in the lamellar tissues compared with the hay group. Correlation analysis indicated that the expression of pro-inflammatory cytokines were positively correlated with MMP-2 expression in lamellar tissues. Overall, these results revealed that HG feeding altered the patterns of rumen fermentation and the composition and functions of rumen bacterial community, and lead to higher levels of LPS in the peripheral blood, and further activated the inflammatory response in lamellar tissues, which may progress to the level of laminar damage.     

Effects of feeding high-quality hay with graded amounts of concentrate on feed intake,performance and blood metabolites of cows in early lactation

Dairy cows are commonly fed energy-dense diets with high proportions of concentrate feedstuffs to meet the increased energy needs of early lactation. However, feeding large amounts of concentrates may cause rumen acidosis and impact cow health. The hypothesis tested was that the energy supply and metabolic health of early-lactation Simmental cows can be maintained when high-quality hay rich in water-soluble carbohydrates (WSC) and crude protein (CP) is fed, despite the proportion of concentrates in the diet being reduced or even excluded. Twenty-four Simmental cows were allocated to one of four feeding groups beginning 10 d before the expected calving date, until 28 d thereafter. The feeding groups were 60CH (60% conventional fibre-rich hay plus 40% concentrate feed), 60HQH (60% high-quality hay plus 40% concentrate feed), 75HQH (75% high-quality hay plus 25% concentrate feed) and 100HQH (100% high-quality hay). The fibre-rich hay and high-quality hay differed in WSC content (110 g vs. 198 g of dry matter (DM)), neutral detergent fibre (646 g vs. 423 g of DM) and CP (65 g vs. 223 g of DM). Individual feed intake and milk production were monitored daily, and blood samples were collected weekly. Dry matter intake (DMI) and milk yield increased post partum, but 4 weeks post partum, the DMI of cows fed 100HQH only reached a daily mean DMI of 18.6 kg, whereas the DMI of the other groups averaged 21.9 kg (p < 0.046). The negative energy balance was less pronounced in cows fed 75HQH since they showed similar milk yields to the cows fed 60CH and 100HQH, but their energy intake was higher. Concentrations of milk components were similar across rations 60CH, 60HQH and 75HQH, as were most of blood parameters. Cows fed 100HQH responded to the energy deficit post partum with a higher ratio of non-esterified fatty acids to cholesterol and a higher concentration of ß-hydroxybutyrate (significant in comparison to cows fed 75HQH, p < 0.05). In conclusion, feeding high-quality hay with a WSC content of 20% in DM has the potential to decrease the proportion of concentrates in dairy cow feeding in early lactation, but cannot fully replace their supplementation due to a limited rumen capacity for forage intake.     

Effect of wheat hay particle size and replacement of wheat hay with wheat silage on rumen pH,rumination and digestibility in ruminally cannulated non-lactating cows

This study examined the effects on intake, diurnal rumen pH changes, rumination and digestibility of feeding ruminally cannulated non-lactating cows in a Latin square design (four cows×four periods) with four total mixed rations (TMRs) typical for lactating cows. TMRs were based on: long wheat hay or short wheat hay, wheat silage or wheat silage+1.5% NaHCO₃ buffer, as the sole roughage source (30% of TMR dry matter (DM)). The level of physically effective NDF remaining above the 8 mm screen (peNDF) was similar in the long hay and silage-based TMRs (9.45% to 9.64% of DM) and lower in the short hay TMR (7.47% of DM). The four TMRs were offered individually at 95% of ad libitum intake to avoid orts within 24 h. Cows fed long hay consumed less DM than the short hay and silage groups (9.6 v. 10.5 and 10.8 kg/day, respectively) and sorted against large hay particles at 12 h post-feeding. Under the limitations of this study (non-lactating cows fed at restricted intake) short hay TMR prevented sorting within 12 h post-feeding, encouraged rumination per kg peNDF ingested, and had higher average rumen pH (6.24), whereas preventing sub acute ruminal acidosis (SARA, defined as pH<5.8 for at least 5 h/day). In contrast, the long hay and silage-based groups were under SARA. In vitro methane production of rumen fluid was higher in the hay-fed cows than in their silage-fed counterparts, and in all treatments lower at 1 h pre-feeding than at 6 h post-feeding. In vivo DM and NDF digestibility were similar for the short hay and silage TMRs, and higher than those of the long hay TMR. Under the conditions of this study, addition of 1.5% buffer to the wheat silage TMR had no effect on intake, rumen pH, creation of SARA and digestibility.     

Effects of considering the rate of comminution of particles and microbial contamination on accuracy of in situ studies of feed protein degradability in ruminants

Ruminal degradation of dry matter (DM) and crude protein (CP) in samples of soybean meal (SBM), barley grain (BG) and lucerne hay (LH) were measured by an in situ ruminal technique considering either only the outflow rate of particles from the rumen (k_p) or, both k_p and rate of particle comminution (k_c). The effect of correction for the microbial contamination using an ¹⁵N technique was also determined for LH. Degradation and transit studies were completed on three wethers cannulated in the rumen and duodenum and fed a mixed diet of LH and concentrate (2:1 on DM), at an intake level of 50 g DM/kg BW^0.75. Transit studies of concentrates and forages were completed with SBM and LH samples marked with Yb and Eu, respectively. Mean values of k_c were higher in SBM than in LH (0.357 versus 0.204 h, P < 0.05). The same trend was observed for k_p (0.0587 versus 0.0452/h; P < 0.1). Apparent estimates of the proportion of rumen undegraded CP obtained using both rates were 0.884, 0.745 and 0.825 of those obtained using only k_p (0.535, 0.247 and 0.303 for SBM, BG and LH, respectively). Differences occurred for SBM and LH (P < 0.01) and for BG (P < 0.05). The pattern of microbial contamination of LH, expressed as a proportion of residual DM or CP, fitted exponential curves with asymptotic values of 0.076 and 0.586, respectively. Correction for microbial contamination reduced (P < 0.05) estimates of undegraded CP from 0.303 to 0.238, which was further reduced to 0.178 (P < 0.01) when the effect of k_c was also considered.     

Effect of feeding schedule on apparent energy and amino acid digestibility by growing pigs

An experiment was conducted to investigate the effects of feeding schedule on dry matter (DM), gross energy (GE), crude protein (CP), and amino acid (AA) digestibility by growing pigs. Six growing castrates (initial body weight: 40.5 ± 2.25 kg) were equipped with a T-cannula in the distal ileum and allotted to a repeated 3 × 3 Latin square design with three animals and three periods in each square. A maize–soybean meal based diet (181 g CP/kg) was formulated and fed to the pigs in three different feeding schedules; i.e., one meal per day, two meals per day, or free access to feed. Pigs fed one or two meals per day were allotted a daily amount of feed equivalent to three times the maintenance energy requirement. Fecal and ileal samples were collected from all pigs in each period. The coefficients of ileal apparent digestibility (CIAD) for DM, GE, CP, and AA were calculated as were the coefficients of total tract apparent digestibility (CTTAD) of DM and GE. Results of the experiment showed that there were no differences in the CIAD for DM, GE, or for any of the AA among the three feeding schedules. In contrast, pigs given free access to the diet had lower (P<0.002) CTTAD for DM and GE compared with pigs fed a restricted amount of feed either once or twice daily. Therefore, the concentration of digestible energy in the diet was lower if calculated from pigs given free access to the diet compared with pigs fed the diet once or twice daily (14.38 MJ/kg versus 14.83 MJ/kg and 15.13 MJ/kg). It is concluded that the feeding schedule does not influence the CIAD for DM, GE, CP, or AA by pigs. Therefore, any of the three feeding schedules that were used in the current experiment may be used in experiments aimed at measuring CIAD in pigs. However, if the CTTAD of DM and GE are measured, it is recommended that pigs are given free access to feed.     

Effects of dietary crude protein and tannic acid on rumen fermentation,rumen microbiota and nutrient digestion in beef cattle

The objectives of the trial were to study the effects of dietary crude protein (CP) and tannic acid (TA) on rumen fermentation, microbiota and nutrient digestion in beef cattle. Eight growing beef cattle (live weight 350 ± 25 kg) were allocated in a 2 × 2 crossover design using two levels of dietary CP [111 g/kg dry matter (DM) and 136 g/kg DM] and two levels of TA (0 and 16.9 g/kg DM) as experimental treatments. Each experimental period lasted 19 d, consisting of 14-d adaptation and 5-d sampling. The impacts of dietary CP and TA on ruminal microbiota were analysed using high-throughput sequencing of 16S rRNA gene. Results indicated that no interactions between dietary CP and TA were found on rumen fermentation and nutrient digestibility. Increasing dietary CP level from 111 to 136 g/kg DM increased the ruminal concentrations of ammonia nitrogen (NH₃-N) (p < 0.01) and improved the CP digestibility (p < 0.001). Adding TA at 16.9 g/kg DM inhibited rumen fermentation and decreased the digestibility of dietary CP (p < 0.001), DM (p < 0.05) and organic matter (p < 0.01). Increasing the dietary CP level or adding TA did not affect the relative abundances of the major bacteria Firmicutes and Proteobacteria at the phylum level and Prevotella_1 and Christensenellaceae_R-7_group at the genus level, even though adding TA increased the Shannon index of the ruminal bacterial community. TA was partly hydrolysed to pyrogallol, gallic acid and resorcinol in rumen fluid and the inhibitory effects of TA on rumen fermentation and nutrient digestibility could have been resulted from the TA metabolites including pyrogallol, gallic acid and resorcinol as well as the protein-binding effect.     

Effects of feeding nutritionally balanced rations on animal productivity,feed conversion efficiency,feed nitrogen use efficiency,rumen microbial protein supply,parasitic load,immunity and enteric methane emissions of milking animals under field conditions

Milking animals produce milk commensurate with their genetic potential only when they are fed a nutritionally balanced ration in an amount that provides nutrients to express their genetic potential. As animals kept by smallholder farmers are rarely fed a balanced ration, a programme to feed balanced rations to animals of such farmers was launched in India. Based on their milk yield, the animals were categorized as: low (<8 kg/d), medium (8–12 kg/d) and high (>12 kg/d) yielders. Milk yield, milk fat and net daily income to milk producers were recorded before and after feeding a balanced ration. Nutritional status of animals showed that, for 71% of animals’, crude protein (CP) and metabolizable energy intakes were higher and, for 65% of animals’, calcium and phosphorus intakes were lower than requirements. Ration balancing improved milk yield by 2–14% and its milk fat proportion by 0.2–15%. Feed conversion efficiency, as kg of fat corrected milk (FCM)/kg of dry matter intake of buffaloes (n = 1131) before and after feeding balanced rations was 0.6 and 0.7, respectively, and in cows (n = 540) the values were 0.6 and 0.8. Dietary N secreted into milk increased from 0.16 to 0.25 and 0.16 to 0.19 in low and medium yielding cows and buffaloes, respectively. Rumen microbial CP synthesis also increased (P<0.05) by 36 and 38% in cows and buffaloes, respectively. On feeding balanced rations, levels (mg/ml) of plasma immunoglobulins IgG, IgM and IgA increased from 14.48 to 22.11, 2.69 to 3.29 and 0.48 to 0.67, and the parasitic load was reduced from 168 to 81 eggs/g of faeces. Enteric CH₄ emissions (g/kg milk yield) was reduced by 15–20% (P<0.05) in these lactating animals. Results demonstrate that feeding nutritionally balanced rations increased milk production and reduced enteric CH₄ emissions and N excretion from lactating cows and buffaloes. While implementation of a ration balancing programme under small holding systems is challenging, large scale use of this programme in tropical countries can help improve productivity of milking animals with available feed resources in an environmentally sustainable manner.     

Influence of gradual adaptation of cattle to Leucaena leucocephala leaf meal on biodegradation of mimosine and 3- hydroxy-4(1H)-pyridone (3,4 DHP) in rumen,their levels in blood,fate and influence of absorbed DHP on thyroid hormones and liver enzymes

Three rumen fistulated Karan Fries crossbred (Holstein X Tharparkar) calves were fed increasing dry matter (DM) levels of 25%, 50%, 75% and 100% through leucaena leaf meal (LLM) starting at week 1, 2, 3 and 4, respectively. The mimosine, 3,4 DHP and 2,3 DHP levels were determined in strained rumen liquor (SRL) and serum at 0, 1, 2, 4, 8, 12 and 24 h postfeeding on days 1, 8, 15, 22, 29 and 42. LLM was incubated for 24 h with SRL in vitro on days 0, 7, 14, 21, 28 and 41 to study mimosine and dihydroxypyridone (DHP) biodegradation. On day 43, 1–1.5 l of rumen liquor was transferred to another set of three unadapted calves which were fed 50% LLM after transfer of inoculum. DM intake was 1.78%, 2.13%, 2.27%, 1.66%, 1.54% and 1.35% of live weight during the 1st through 5th week, respectively. Both in vitro and in vivo studies showed extensive degradation of mimosine to 3,4 DHP and 2,3 DHP from first day of LLM feeding. The overall in vitro DHP degradation was nil, 28.6%, 43.3% and 40.1% on day upto 15, 21, 28 and 42 of LLM feeding. No mimosine was found in serum on any day of sampling. The 3,4 DHP detected (56.94±31.65 μg ml⁻¹ serum) one hour post feeding on day 1 exhibited a decline from day 22 onwards. The serum also contained 2,3 DHP on days 8, 15, 22, 42. The faecal and urinary excretion of 3,4 DHP and 2,3 DHP as percent of mimosine intake declined from first week (76.3±2.8) to 4th week (42.1±4.1). The feeding of LLM resulted in reduced level of T₃ and T₄ within a week of LLM feeding. The level of T₃ improved to normal by 6th week while that of T₄ remained low. The SGOT and SGPT activities were within normal range. The gradual adaptation to LLM feeding caused Karan Fries calves to acquire DHP degrading ability to nontoxic compounds and this ability was transferred through transfer of rumen liquor from such calves to other unadapted calves at as early as 9th day of LLM feeding. The results revealed the possibility of two types of microbes degrading mimosine and 3,4 DHP to 2,3 DHP. One type of 2,3 DHP degrading microbes may be inhibited in the presence of 3,4 DHP whereas the other type may be active.     

Effects of ensiling on in situ ruminal degradability and intestinal digestibility of corn forage

The effective degradability of dry matter (DM), crude protein (CP) and amino acids (AA), and the intestinal effective digestibility (IED) of DM and CP of a green forage corn (GC) and its silage (EC) were determined on freeze-dried samples using three rumen and duodenum cannulated wethers. Two rumen incubations with duplicate bags were performed for each feed. Rumen degradation was determined on one series of bags from each incubation. The other series was freeze-dried and used to determine IED using mobile nylon bags. Microbial contamination of rumen incubated residues (determined with ¹⁵N techniques) fitted exponential functions, which showed a greater microbial contribution in EC than in GC in the undegradable DM (18.6% vs. 13.5%) and CP (81.7% vs. 69.4%). Degradability was calculated considering the particle rumen outflow rate (k_p : 0.056/h) of the EC (ED_p) or additionally the rate of comminution and mixing (k_c : 0.130/h) of these particles (ED_cp). Ensiling increased ED_p (9.33%, p < 0.01) or ED_cp (5.30%, p = 0.062) of DM and was associated with losses of nitrogen and with large changes in the AA profile. It is necessary to correct the microbial contamination, because it represents 32.0% (GC) and 42.5% (EC) of the undegraded CP when using k_p and k_c . Ensiling caused higher degradabilities for some AA as well as large differences in the changes due to the rumen fermentation on the AA profile. However, it had only limited effects on the undegraded protein profile. Ensiling also reduced the IED of DM (23.3% vs. 14.6%; p = 0.057). In conclusion, results do not show losses of nutritive value by ensiling corn cut at vitreous grain stage.     

Effect of moist heat treatment on in-vitro degradability and ruminal escape protein and amino acids of mustard meal

A study was conducted to determine the effects of moist heat treatment (127°C, 117 kPa steam pressure) for 10 min on protein fractions and in-vitro crude protein (CP) degradability of mustard meal. Rumen undegraded protein (RUP) and amino acid disappearance of unheated, and heated, mustard meal were measured following 12 h of rumen incubation using two ruminally fistulated cows. Intestinal availability of RUP was estimated using an enzymatic (pepsin–pancreatin) procedure. Heat treatment reduced (p<0.05) protein solubility and increased (p<0.05) neutral detergent insoluble CP without affecting acid detergent insoluble CP of mustard meal. Relative to the control, heated mustard meal had a lower (p<0.05) effective in-vitro CP degradability (445.2 vs. 746.8 g kg⁻¹ of CP) and a higher (p<0.05) ruminal escape CP (615.1 vs. 120.2 g kg⁻¹ of CP) value. Amino acid composition was not affected by heat treatment except for the concentration of arginine and lysine which was lower (p<0.05) in heated than in unheated mustard meal. Disappearance of all amino acids following 12 h of rumen incubation was lower (p<0.05) in unheated than in heated mustard meal. Heat treatment increased (p<0.05) the amount of protein available for digestion in the small intestine from 75.7 to 518.1 g kg⁻¹ of CP. It was concluded that moist heating of mustard meal for 10 min will reduce ruminal CP and amino acid degradability without compromising the intestinal availability of ruminal undegraded protein.     

Using mixed silages of sweet sorghum and alfalfa in total mixed rations to improve growth performance,nutrient digestibility,carcass traits and meat quality of sheep

Combining sweet sorghum (SS) with alfalfa for ensiling has the potential to make a high-quality silage with relatively a better nutrient balance. However, the existing data are insufficient about how changes in ratios of SS to alfalfa in different silage mixtures affect animal performance and meat quality. Therefore, the objective of this study was to determine the effect of feeding total mixed rations containing mixed silages of SS and alfalfa on growth performance, nutrient digestibility, carcass traits and meat quality of Karakul sheep. Five total mixed rations were formulated with different SS proportions at 100%, 80%, 60%, 40%, and 20% on a fresh weight basis. Thirty 4-month old male Karakul sheep with 25.5 ± 1.4 kg BW were randomly allocated into five treatment groups, each with six lambs for this experiment. The results indicated that the Karakul sheep consuming total mixed rations containing SS-Alfalfa (SS-AF) silage mixtures with a lower proportion of SS tended to increase nutrient digestibility, growth performance, carcass traits, and meat quality. Feeding diets with SS at 40% and 20% inclusion rate showed a significant linear increase in the apparent digestibility of DM, CP and NDF, as well as subcutaneous fat thickness and water holding capacity (P < 0.5). Moreover, reduction in SS inclusion rate in these diets caused significant (P < 0.05) linear and quadratic increases in DM intake, final BW, average daily gain, carcass weight, and the amino acid contents of meat (P < 0.05). Conversely, feeding diet with lower SS inclusion rate led to decrease in feed conversion ratio and shear force significantly (P < 0.05) for these sheep. It appears that 40% inclusion of SS was the optimal rate in making the SS-AF silage mixture for lambs to achieve a superior production performance and high-quality meat products in Karakul sheep. However, further research is needed to investigate the effect of feeding SS-AF silage mixtures alongside contrasting ingredients on rumen function, ruminal microorganisms and digestive enzyme activity of sheep and other ruminant animals.     

Effect of feeding long or short wheat hay v. wheat silage in the ration of lactating cows on intake,milk production and digestibility

The objective of this study was to evaluate in lactating cows the effect of either chopping or ensiling of wheat roughage on: intake, digestibility, lactation performance and animal behavior. Three groups of 14 lactating cows each, were fed total mixed rations (TMRs) based on either long wheat hay (HL), short wheat hay (HS) or wheat silage (SI), as the sole roughage source (30% of TMR dry matter (DM)). Parameters examined: sorting behavior, DM intake, milk yield and composition, rumination, recumbence, average daily rumen pH, digesta passage rate, and in-vivo digestibility. Performance data was summarized by day and analyzed using a proc-mixed model. The content of physically effective neutral detergent fiber (peNDF) was similar in the HL and SI and lower in the HS, resulting in similar differences among the three corresponding TMRs. In vitro DM digestibility of wheat silage was higher than that of the two hays (65.6% v. 62.8%) resulting in higher in vitro DM digestibility of the SI-TMR compared with the hay-based TMRs (79.3 v. 77.0%). HS-TMR was better than HL- or SI-TMRs at preventing feed sorting by cows after 12 or 24 h eating of the diets. Cows fed HS-TMR consumed more DM and NDF but less peNDF than the other two groups. Average daily rumen pH was similar in the three groups, but daily rumination time was highest in the cows fed HS-TMR. Rumen retention time was longest in cows fed HL-TMR. DM digestibility in cows fed SI-TMR was higher than that of HS and HL groups (65.2%, 61.8% and 62.4%, respectively), but NDF digestibility was similar in the three treatments. The highest intake of digestible DM was observed in cows fed SI-TMR, HS cows were intermediate and HL cows were the lowest. Consequently, cows fed SI-TMR had higher yields of milk, 4% fat corrected milk and energy-corrected milk (47.1, 42.9 and 43.2 kg/day, respectively) than cows fed HS-TMR (45.7, 41.0 and 41.0 kg/day, respectively) or HL-TMR (44.1, 40.3 and 40.3 kg/day, respectively). Net energy production (NE_L+M+gain) per kg DM intake was highest in the SI-TMR, lowest in the HS-TMR and intermediate in the HL-TMR (1.52, 1.40 and 1.45, respectively). Animal welfare, as expressed in daily recumbence time and BW gain was similar in the SI and HS groups and higher than the HL cows.     

Degradability characteristics of dry matter and crude protein of forages in ruminants

Twelve corn silages, 22 grass silages and 14 grass hays, obtained from various farms located in the lower Fraser Valley region of British Columbia, and 16 alfalfa hays, grown primarily in the Columbia basin of central Washington State, were evaluated using both the rumen and the mobile nylon bag in situ techniques. Nylon bags containing each forage were incubated in duplicate for 0, 2, 4, 8, 12, 24, 48, 72, or 96 h in two of six non-lactating Holstein cows fitted with rumen and duodenal cannulae. All forage types were evaluated in terms of the following dry matter (DM) and crude protein (CP) digestion characteristics: soluble fraction A, degradable fraction B, degradation rate, lag phase, and effective degradability. The mobile nylon bag technique was used to determine intestinal disappearance of DM and CP from the forages following pre-incubation in the rumen for 12 h. Significant (P < 0.05) differences in degradation characteristics occurred within all forages with regard to the soluble and potentially degradable DM and CP fractions. Soluble CP content in the rumen varied from 44.08 to 75.37% and from 18.74 to 65.38% in the corn and grass silages, respectively, and from 48.27 to 75.43% and from 30.13 to 65.95% in the alfalfa and grass hays, respectively. Significant differences within each forage type were also observed for the degradable CP in fraction B: 10.89 to 45.28% for corn silage, 20.72 to 82.77% for grass silage, 16.67 to 44.88% for grass hay and 25.44 to 62.93% for alfalfa hays. Significant differences (P > 0.05) were observed in fractional rates of ruminal DM degradation of the grass hays and corn silages. Significant differences did exist in the fractional rates of ruminal CP degradation within all forage types with the exception of alfalfa hays. Effective degradabilities of DM and CP were also significantly different between samples of a particular forage type. The mobile nylon bag data indicated that approximately 20% of the original CP in the grass silage, grass hay and alfalfa hay samples disappeared in the intestine and that there was significant variation between individual samples. On average, in the corn silage samples more than 10% of the original nitrogenous material disappeared in the intestine. The results presented in this study clearly demonstrate that the use of tabulated values for describing individual batches of forages in terms of their degradability characteristics is inaccurate since they may not reflect the particular forage being used in the ration and thus may lead to errors in diet formulation.     

Effects of feeding propylene glycol to mid-lactating dairy cows

Propylene glycol (PG) is a gluconeogenic precursor widely used to prevent and treat ketosis postpartum. The study has investigated the effects of PG administration to dairy cows at mid stage of lactation. According to a 3 × 3 latin square design, three Italian Brown lactating cows (125 ± 7 days in milk) fitted with rumen cannula were fed a corn silage based diet (CP 14.7%, NDF 41.1% DM) with 0, 200 or 400 g day⁻¹ PG added. Dry matter intake was increased by feeding PG with a significant quadratic component per dose (16.2, 17.2 and 16.5 kg day⁻¹ for 0, 200 and 400 g PG day⁻¹, respectively). Milk yield was not affected by PG, averaging 17.1 kg day⁻¹. Average daily gain increased from 64 to 206 and 302 g day⁻¹ when cows received 200 and 400 g day⁻¹ of PG (linear component per dose P < 0.05). Digestibility of the diet did not differ among treatments, whereas repeated rumen fluid samples, taken 0, 2, 4, 6 and 8 h after the meal, showed a consistently lower acetate to propionate ratio when feeding PG. Blood insulin was not affected by PG administration. Except for therapeutic treatments, PG administration to dairy cows at mid stage of lactation should be advised against. Despite the positive effect on intake, administration of the additive, increasing the molar percentage of rumen propionate, contributes to shift the energy partition from milk production to liveweight gain.     

Diet selection and eating behaviour of lactating goats subjected to time restricted feeding in choice and single feeding system

This study was carried out to investigate diet selection and eating behaviour of lactating German Fawn × Hair Crossbred goats in different feeding methods and levels. Twenty German Fawn × Hair first backcross does (B₁) were allocated into 4 treatment groups (2 feeding methods single (TMR) and choice feeding × 2 feeding levels ad libitum and restricted) with 5 replicates. Restricted feeding was applied only 4 h feed allocation during day. Barley, corn, soybean meal, corn gluten meal, wheat bran and alfalfa hay were feed ingredients for single and choice feeding. Eating patterns, milk yield and composition were determined for 8 weeks. The following results were obtained: (1) the meal criteria for goats restricted single and choice-fed, ad libitum single and choice-fed were determined as 1.00 and 0.63, 12.88 and 10.23 min, respectively. (2) Ad libitum feeding increased meal size, meal length, intermeal interval, total eating duration and decreased eating rate and meal number, compared to restricted feeding (P < 0.01). Choice feeding decreased meal size (P < 0.05), meal length (P < 0.01) and increased eating rate and meal number (P < 0.01), compared to single feeding. Restricted fed goats decreased intermeal interval in single feeding compared to choice feeding (P < 0.01), but increased meal number in choice feeding (P < 0.01). (3) Ad libitum choice-fed does made a diet containing 12.79% corn, 35.41% barley, 13.21% wheat bran, 5.35% soybean meal, 1.28% corn gluten meal and 29.80% alfalfa meal while restricted choice-fed does made a diet having more corn (27.69%), corn gluten meal (5.62%) and wheat bran (16.17%) and less barley (14.37%) and soybean meal (4.51%). (4) Choice feeding decreased RUP intake (P < 0.05) without affecting milk protein, irrespective to feeding levels, while having a tendency to increase in milk yield (14.2%) and 4% FCM (8.8%). (5) Restricted feeding decreased DM, ME, ADF and NDF intakes (P < 0.05) with concomitant decreases in 4% FCM, total milk solid, ash and fat compositions (P < 0.05), irrespective to feeding methods. (6) Choice-fed goats changed their preferences for a possible synchronized nutrient intake during a daytime, as sorted barley, soybean meal and alfalfa hay from early morning to late afternoon.It could be concluded that choice-fed goats have the ability to make their diet to meet nutrient requirements and had a tendency to increase in milk yield. Restriction in feeding time resulted in lower feed intake and milk yield, although the animal changed their feed preference in favour of high quality ingredients and eating pattern with lower meal criterion and intermeal interval.     

Partial replacement of barley grain and soybean meal by fleabane (Conyza bonariensis) in diets of growing Awassi lambs

Effects of partial substitution of barley grain and soybean meal with fleabane (FB) Conyza bonariensis on growth performances and body compositions of 24 male local Awassi lambs were studied. All lambs were male with an average BW of 20.3 kg (s.d. = 2.0 kg) at the beginning of the experiment. Animals were randomly divided into four groups of six lambs each. Lambs in each group received individually their cereal–soybean-based total mixed rations with levels of FB: 0, 50, 100 and 150 g/kg dry matter (DM) diet, which replaced similar values of barley and soybean meal. All rations were isonitrogenous and isocaloric. The fattening experiment lasted 9 weeks, after which all lambs were slaughtered. The composition of nutrients in the C. bonariensis were 89.6%, 15.0%, 28.0%, 30.0% and 10% for organic matter, CP, NDF, ADF and lignin, respectively. At the end of the experiment, lambs fed 100 and 150 g FB/kg DM diets gained more weight (P < 0.05) than those fed the control and 50 g FB/kg DM diets. The DM intake was lower in lambs fed the highest level of FB compared with intakes of lambs in other treatments. Diet content of FB had significant effect (P < 0.05) on weights of empty body, carcass, gut and external (hide, head and feet) among all animals. However, FB had no effects on lambs’ thoracic organs (lungs and heart) and liver. Muscle, bone, omental and mesenteric fat, subcutaneous, intermuscular, pelvic and kidney fat weights (g/kg empty BW) were not affected by FB feeding. Carcass fat was decreased (P < 0.05) by the increase of FB. Total body fat was the same in all animals of the experiment.     

Variation of lupin protein degradation in ruminants studied in situ and using chemical protein fractions

The main objective of this study was to evaluate the variability in in situ CP degradation characteristics of 15 batches lupin grains from nine genotypes in a standardised approach. This study also investigated whether differences in CP degradation can be described by protein fractionation using the Cornell Net Carbohydrate and Protein System (CNCPS) and also whether thermal processing of lupins has an effect on CP degradation in the rumen and analysed protein fractions. The rising political and consumer demand for milk products from dairy production systems based on domestic protein sources and the wide range of lupin types and varieties that can be chosen as protein feed in dairy nutrition requires research to determine the variability in CP degradation characteristics in the rumen. For CP degradation measurements, ground grains were incubated in the rumen of three lactating Jersey cows fitted with a ruminal cannula for different times from 2 to 48 h, and the washing loss of non-incubated samples was also measured. Protein fractions were analysed according to CNCPS and used for the estimation of ruminally degraded protein. In situ CP degradation parameters varied widely between untreated samples. The mean value for the washout fraction was 29.3% (from 16.4% to 43.6%). The potentially degradable fraction averaged 70.5% (from 55.6% to 83.7%), hence maximal degradation of CP was close to completeness. Mean degradation rate was 16.6%/h (from 12.6 to 21.0%/h). Variation in estimated parameters led to variation in the effective degradation (ED) averaging 76.6% (from 67.3% to 83.0%) when calculated assuming a ruminal outflow of 8%/h. Thermal treatment of lupins induced changes in degradation characteristics, primarily by lowering degradation rates, and also led to a significant reduction in ED. The ED calculated from analysed protein fractions averaged 10 percentage points higher than ED calculated from in situ parameters for untreated grains. The ED based on protein fractionation was also reduced by heat treatment, but the correlation with in situ based ED was poor. It can be concluded that the variation in ED indicates a potential to increase the amount of rumen undegraded protein without additional chemical or physical treatment and the effect of genetic factors and agronomic practices on ED of lupin grains should be investigated in systematic studies in the future.     

Variation of in situ rumen degradation of crude protein and amino acids and in vitro digestibility of undegraded feed protein in rapeseed meals

In this study, 10 samples of rapeseed meal (RSM) from 10 different oil plants in Germany were examined. In situ rumen degradation of CP was determined by incubation over 1, 2, 4, 8, 16, 32 and 72 h in duplicate per time point using three rumen fistulated dry cows. Degradation kinetics were estimated by an exponential model and effective CP degradation was calculated. Degradation was corrected for small particle loss as the difference between washing loss and water-soluble fraction. Amino acid analysis was carried out in the samples and in the residues after 8 and 16 h of incubation in situ and degradation of individual amino acids was calculated for these incubation times. In vitro pepsin–pancreatin digestibility of CP (IPD) was determined in the samples as well as in the 8 and 16 h residues. Effective CP degradation for a rumen outflow rate of 8%/h (ED8) averaged 54.3% with a considerable variation among samples ranging from 44.3% to 62.7%. A multiple regression equation containing acid detergent insoluble N, total glucosinolates and petroleum ether extract as independent variables predicted ED8 with satisfying accuracy (R² = 0.74; RSD = 6.4%). Degradation of amino acids was different from that of CP for most amino acids studied, especially after 8 h of incubation. Compared with CP, degradation of essential amino acids was predominantly lower while degradation of non-essential amino acids was higher in most cases. However, for lysine and methionine no distinct difference with CP degradation was found. Degradation of individual amino acids was predicted from CP degradation with high accuracy using linear regression equations. Average IPD of RSM was 79.8 ± 2.6%. IPD was lower in the incubation residues and decreased with longer incubation time and increasing rumen degradation, respectively.     

Utilisation of fish oil in ruminants: I. Fish oil metabolism in sheep

Five sheep with rumen and abomasal cannulae were offered three diets sequentially in the order: control (C) pellets (lucerne hay-oat grain: 60/40, w/w), control plus unprotected tuna oil (UTO pellets), and control plus tuna oil protected (casein-formaldehyde matrix) against ruminal biohydrogenation (PTO pellets). In supplemented diets, tuna oil constituted 3% (w/w) of total dry matter (DM), and each supplement was fed for 12 days, with 9 days allowed between the two fish oil feeding periods to minimise carry-over effects. Daily DM intake was 785±38 g/head during the control period. It was significantly reduced by UTO feeding (6.2%, P<0.05) but not PTO feeding. The level of EPA in the abomasum during PTO feeding was double that measured during UTO feeding (1.30 versus 0.61% of FA, P<0.05). The level of DHA in the abomasum did not significantly differ between UTO and PTO feeding periods. Both tuna oil supplements significantly increased the levels of 18:1 trans and that of a fatty acid derivative identified as 10-hydroxystearic acid (10-HSA) in both the rumen and abomsum. Tuna oil supplementation also altered the fatty acid composition of plasma lipid fractions and 10-HSA was solely incorporated into plasma free fatty acids. This study indicates that substantial protection of tuna oil against ruminal hydrogenation inhibited reduced feed intake, but increased the proportion of 18:1 trans isomer and fatty acids derivatives (10-HSA), which indicate interference with metabolism in the rumen.