Mid Lactation Research Articles

The Effects of Cassava Pomace and Protected Soybean Meal on Dairy Milk Production and Quality

The objective of the study was to determine the effect of cassava pomace and protected soybean meal on dairy milk production and quality of mid lactating dairy cows. This research was conducted at Turen, Malang from January to April 2020. Twelve lactating Friesian Holstein dairy cows were divided into 2 groups so that each group consisted of 6, namely the control and treatment groups. The feed were a combination of forage and concentrate with a ratio of 35:65 in dry matter (DM). The control group received wet concentrate with DM content of 30.58%, 14.87% CP, and 75.06% TDN, while the treatment groups received concentrate with supplementation of cassava pomace 15% of DM ratio and protected soybean meal 45 g/l milk production. The variables observed were nutrient consumption, milk production and quality. Data between the two groups were analyzed using the Independent Sample T-test. The results showed that the addition of waste cassava and protected soybean meal increased (P<0.05) nutrient consumption (DM, OM, CP, CF, EE, and TDN). Milk production in the treatment group was higher (P<0.05) than control group (9.46 vs. 6.07 Ls/head/day). Milk protein production in the treatment group was higher (P<0.05) than control group (0.37 vs. 0.21 L/head/day). The content of milk protein and milk fat between the control and treatment groups was not significantly different (respectively 3.19 Vs 3.28; 4.46 vs 4.42 %). Milk protein and fat production in the treatment group was higher (P<0.05) than control group (0.21 vs 0.37; and 0.50 vs. 0.30 L/head/day respectively). The composition of glucose and blood urea in control and treatment dairy cows were not significantly different. In conclusion, giving cassava pomace and protected soybean meal to dairy cows during mid lactation increased nutrient consumption, milk production, milk protein production, and milk fat production but did not increase percentage of milk protein and fat. The treatment also did not affect blood glucose and nitrogen urea contents.

Effects of corn grain endosperm type and fineness of grind on site of digestion, ruminal digestion kinetics, and flow of nitrogen fractions to the duodenum in lactating dairy cows

Our objective was to evaluate effects of corn grain endosperm type and fineness of grind on feed intake, feeding behavior, and productive performance of lactating cows. Eight ruminally and duodenally cannulated Holstein cows in mid lactation (130 ± 42 d in milk; mean ± standard deviation) were used in a duplicated 4 × 4 Latin square design with 21-d periods. A 2 × 2 factorial arrangement of treatments was used with main effects of corn grain endosperm type (floury or vitreous) and fineness of grind (fine or medium). Rations included alfalfa silage, corn treatments, protein supplement, minerals, and vitamins and were formulated to contain 29% starch, 27% neutral detergent fiber, 18.2% forage neutral detergent fiber, and 18% crude protein. Corn grain treatments supplied 86.2% of dietary starch. Endosperm was 25% vitreous for the floury treatment and 66% vitreous for the vitreous treatment. The floury treatment increased rate of starch degradation by 94% (19.2 vs. 9.9%/h) and decreased rate of starch passage by 38% (16.1 vs. 25.8%/h), increasing apparent ruminal starch digestibility by 117% (53.7 vs. 24.7%). The floury treatment increased total-tract starch digestibility by 8% (92.2 vs. 85.1%) despite 37% lower postruminal starch digestion for the floury treatment compared with vitreous corn (38.4 vs. 60.7% of starch intake). Fine grind size increased apparent ruminal starch digestibility by 52% (47.2 vs. 31.1%) compared with medium grind size by increasing the rate of starch degradation by 105% (19.5 vs. 9.5%/h) with no effect on rate of starch passage. However, total-tract starch digestibility was not affected by fineness of grind because postruminal starch digestibility was 37% greater for medium compared with fine grind size (57.2 vs. 41.9% of starch intake). Endosperm type did not affect flow of nitrogen (N) fractions to the duodenum or microbial N efficiency, whereas fine grind size increased duodenal flow of nonammonia N by increasing duodenal flow of microbial N by 22% compared with medium grind size (438 vs. 359 g/d) but did not affect apparent total-tract N digestibility. No interactions were detected for any measure of starch digestion, ruminal N metabolism, or flow of N fractions to the duodenum. Endosperm type greatly affected ruminal and total-tract starch digestibility independent of the fineness of grind of corn grain with no effects on flow of N fractions.

Effects of corn grain endosperm type and fineness of grind on feed intake, feeding behavior, and productive performance of lactating dairy cows

Our objective was to evaluate effects of corn grain endosperm type and fineness of grind on feed intake, feeding behavior, ruminal fermentation, and productive performance of lactating cows. Eight ruminally and duodenally cannulated Holstein cows in mid lactation (130 ± 42 d in milk; mean ± standard deviation) were used in a duplicated 4 × 4 Latin square design with 21-d periods. A 2 × 2 factorial arrangement of treatments was used with main effects of corn grain endosperm type (floury or vitreous) and fineness of grind of corn grain (fine or medium). Rations were formulated to contain 29% starch, 27% neutral detergent fiber, 18.2% forage neutral detergent fiber, and 18% crude protein. Corn grain treatments supplied 86.2% of dietary starch. Endosperm was 25% vitreous for floury corn and 66% vitreous for vitreous corn. Fineness of grind did not affect dry matter intake (DMI), but floury corn tended to reduce DMI (23.8 vs. 25.1 kg/d) compared with vitreous corn. Floury corn increased meal frequency more for fine grind size (9.57 vs. 9.41 meals/d) than medium grind size (9.78 vs. 9.75 meals/d). However, there were no effects of treatment on any other measure of feeding behavior. Endosperm type did not affect yields of milk or milk components or milk composition except that vitreous corn tended to decrease milk lactose concentration compared with floury corn. Finely ground corn decreased yields of milk (31.1 vs. 33.1 kg/d), 3.5% fat-corrected milk (33.1 vs. 35.1 kg/d), milk fat (1.22 vs. 1.32 kg/d), milk lactose (1.48 vs. 1.59 kg/d), and solids not fat (2.46 vs. 2.63 kg/d) compared with medium grind size. However, fineness of grind did not affect milk composition. Treatments had no effect on change in body weight or body condition score or efficiency of milk production (kg of 3.5% fat-corrected milk/kg of DMI). Mean ruminal pH was not affected by treatment, but pH variance was decreased by vitreous compared with floury corn. Total volatile fatty acids and propionate concentrations in the rumen were increased by floury compared with vitreous corn but were not affected by fineness of grind. Effects of fineness of grind on yield of milk and milk components were greater than the effects of corn grain vitreousness.

Effects of the circadian rhythm on milk composition in dairy cows: Does day milk differ from night milk?

Metabolism in most organisms can show variations between the day and night. These variations may also affect the composition of products derived from livestock. The aim of the present study was to investigate the difference in composition between the day milk and night milk of dairy cows. Ten multiparous Holstein cows (milk yield = 25.2 ± 5.00 kg/d) were randomly selected during mid lactation. Milk samples were collected at 0500 h ("night milk") and 1500 h ("day milk") and analyzed to determine their composition. Mid-infrared spectroscopy was used to analyze macronutrient content of milk. Metabolomics and lipidomics were used to detect and analyze small molecules and fatty acids, respectively. An automatic biochemical analyzer and ELISA kits were used to determine biochemical indicators, as well as antioxidant and immune parameters in the milk. Though milk fat, protein, lactose, and total milk solids were not different between day milk and night milk, small molecules, metabolites and lipids, and hormones and cytokines differed between day milk and night milk. Regarding biochemical and immune-related indicators, the concentrations of malondialdehyde, HSP70, and HSP90 in night milk were lower than that in day milk. However, interferon-γ levels were higher in night milk. Additionally, night milk was naturally rich in melatonin. Lipidomics analyses showed that the levels of some lipids in night milk were higher than those in day milk. Metabolomics analyses identified 36 different metabolites between day milk and night milk. Higher concentrations of N-acetyl-d-glucosamine, cis-aconitate, and d-sorbitol were observed in day milk. However, the other 33 metabolites analyzed, including carbohydrates, lipids, AA, and aromatic compounds, showed lower concentrations in day milk than in night milk. The present findings show that the composition of night milk differs considerably from that of day milk. Notable changes in the circadian rhythm also altered milk composition. These results provide evidence to support the strategic use and classification of day milk and night milk.

The hidden cost of disease: I. Impact of the first incidence of mastitis on production and economic indicators of primiparous dairy cows

Mastitis is a highly prevalent disease, which negatively affects cow performance, profitability, welfare, and longevity. The objectives of this study were (1) to quantify the impact of the first instance of mastitis, at different stages of lactation, on production and economic performance, and (2) to further quantify the impact of the first instance of mastitis when only cows that remain in the herd for at least 100 d in milk (DIM) and those that remain for 305 DIM are included in the analysis. A retrospective longitudinal study was conducted using data from existing animal health record files and Dairy Herd Improvement records. After editing based on selected inclusion criteria and completeness of health records, data consisted of records from first-lactation Holstein cows, from 120 herds, that calved for the first time between 2003 and 2014, inclusive. Mastitic cows were assigned to 1 of 4 groups based on when in the lactation the first event of mastitis occurred: transition (1-21 DIM), early lactation (22-100 DIM), mid lactation (101-200 DIM), or late lactation (201+ DIM). Mid-lactation and late-lactation mastitic cows were also stratified by cumulative milk yield before the mastitis event. Healthy cows (i.e., no recorded mastitis event) were randomly assigned for each lactation stage, with mid-lactation healthy and late-lactation healthy cows similarly stratified. Production performance (cumulative milk, fat, and protein yield) and economic performance [milk value, margin over feed cost (MOFC), and gross profit] were analyzed using a mixed model with herd as a random effect. Significant losses in cumulative milk yield (-382 to -989 kg) and correspondingly lower fat and protein yields were found in mastitic cows, with transition and late-lactation mastitic cows having the highest losses. Drops in production translated to significant reductions in cumulative milk value (-Can$287 to -Can$591; -US$228 to -US$470), MOFC (-Can$243 to -Can$540; -US$193 to -US$429), and gross profit (-Can$649 to -Can$908; -US$516 to -US$722) for mastitic cows at all stages. Differences between mastitic and healthy cows in the early lactation and transition stages remained for all variables in the 100-DIM analysis, but, aside from gross profit, were nonsignificant in the 305-DIM analysis. Gross profit accounted for all costs associated with mastitis and thus continued to be lower for mastitic cows at all stages, even in the 305-DIM analysis in which culled cows were omitted (-Can$485 to -Can$979; -US$386 to -US$779). The research reflects the performance implications of mastitis, providing more information upon which the producer can make informed culling decisions and maximize both herd profitability and cow longevity.

Energy, nitrogen partitioning, and methane emissions in dairy goats differ when an isoenergetic and isoproteic diet contained orange leaves and rice straw crop residues

The aim of this study was to evaluate the effects of incorporating rice straw and orange leaves into the diets for goats. Ten Murciano-Granadina goats at mid lactation weighing 45 ± 0.3 kg were used in a crossover design. Two isoproteic and isoenergetic diets (180 g/kg DM and 17 MJ/kg DM, respectively) with alfalfa hay as forage source (33% of DM) were fed. A control diet (CON) incorporated barley as energy source and soy hulls as fiber component. The experimental diet (ORG) replaced barley and soy hulls with orange leaves (19% on DM basis), rice straw (12%, on DM basis) and soya oil (2%). Peas and horsebeans were the protein source in both diets. Each goat received the 2 treatments in 2 periods. Goats were fed the experimental diets and after 14 d on their respective treatments moved to individual metabolism cages for another 7 d. Subsequently, feed intake, total fecal and urine output and milk yield were recorded daily over the first 5 d. During the next 2 d ruminal fluid and blood samples were collected, and then individual gas-exchange measurements were recorded by a mobile open-circuit indirect calorimetry system using a head box. No differences in dry matter intake were detected, and apparent total-tract digestibility was greater in CON than ORG. Efficiency of metabolizable energy intake for milk and maintenance also was lower in response to ORG (0.65 vs. 0.63), with energy balance being negative (-12 kJ/kg of BW0.75) due to mobilization of fat (-16 g/animal vs. 68 g/animal for ORG and CON, respectively). Although actual milk yield was lower in goats fed ORG (2.32 vs. 2.06 kg/d, respectively), energy-corrected milk did not differ (2.81 kg/d on average). In terms of milk quality, milk fat content, and concentrations of monounsaturated (18.54 vs. 11.55 g/100 g milk fat) and polyunsaturated fatty acids (5.75 vs. 3.99 g/100 g milk fat) were greater in goats fed ORG. Based on various indices, the milk produced by ORG would be less atherogenic and thrombogenic than CON milk. Compared with CON, enteric CH4 emission was lower due to feeding ORG (reduction of 38 g CH4/kg milk fat). Data suggest that greater fat mobilization in goats fed ORG might have been due to the apparent lack of synchrony between degradable protein and carbohydrate and the lipogenic nutrients associated with the lower cereal content of the ORG diet. Thus, goats fed ORG seemed to rely more on fat depots to help meet energy requirements and reach optimal performance. As such, the lower content of glucogenic nutrients in ORG did not favor body fat deposition and partitioning of ME into body tissue. Overall, responses in terms of CH4 emissions and milk quality suggest that inclusion of rice straw and orange leaves in diets for small ruminants could be a valuable alternative to reuse, recycle and revalue agricultural by-products.

Changes in nutrient balance, methane emissions, physiologic biomarkers, and production performance in goats fed different forage-to-concentrate ratios during lactation.

The objective was to determine the effect forage-to-concentrate (F:C) ratio and stage of lactation on methane emissions, digestibility, nutrient balance, lactation performance, and metabolic responses in lactating goats. Twenty Murciano-Granadina dairy goats were used in an experiment divided into 3 periods: early (30 d), mid (100 d), and late (170 d) lactation. All goats were fed a diet with 35:65 F:C (FCL) during early-lactation. Then, 1 group (n = 10 goats) remained on FCL through mid- and late-lactation while the other group (n = 10 goats) was fed a diet with 50:50 F:C at mid-lactation (FCM) and 65:35 (FCH) at late lactation. A greater proportion of concentrate in the diet was associated with greater overall intake and digestibility (P < 0.05). Energy balance was negative in early-lactation (-77 kJ/kg of BW0.75, on average) and positive for FCL at mid- and late-lactation (13 and 35 kJ/kg of BW0.75, respectively). Goats fed FCM and FCH maintained negative energy balance throughout lactation. Plasma concentrations of non-esterified fatty acids at mid-lactation were greater for FCM than FCL (680 mEq/L), and at late-lactation concentrations were greater for FCH and FCL (856 mEq/L). A similar response was detected for plasma β-hydroxybutyrate. Methane emission was greater (P < 0.05) for FCM than FCH (1.7 g CH4/d). This study demonstrated that differences in F:C across stages of lactation lead to distinct metabolic responses at the level of the rumen and tissues.

Haemato-biochemical profile during different stages of lactation in local Sahiwal crossbred dairy cows at Savar area of Dhaka district of Bangladesh

The present study was carried out to investigate the haemato-biochemical profile during different stages of lactation in local Sahiwal crossbreed dairy cows at Savar area of Dhaka district of Bangladesh. Twenty four local Sahiwal crossbreed cows were selected randomly from different small farms and divided into three groups: early stage lactation (1-3 months), mid stage lactation (4-6 months) and late stage lactation (7-9 months). Blood samples were collected during three stages of lactation. There were no statistical significant (p&lt;0.05) variations observed in hematological parameters amongst the three stage of lactation. Although the packed cell volume (PCV), hemoglobin (Hb) concentration and RBC count were found lowest in early stage of lactation than the other groups. Total leucocyte count (TLC), platelet count (PLT), mean corpuscular volume (MCV) and mean corpuscular haemoglobin (MCH) were recorded within normal limits. Similarly, biochemical parameters were observed statistically non-significant amongst the groups studied. The glucose level was recorded lowest in early stage of lactation; whereas, the protein and creatinine concentrations were slightly higher in this stage. Aspartate aminotransferase (AST), Alanine aminotransferase (ALT) and Alkaline phosphatase (ALP) were not varied amongst the three groups of cows. Data generated during the current study may be useful as reference values for the scientific community.&#x0D; Asian J. Med. Biol. Res. March 2021, 7(1): 1-5

Effects of replacing soybean meal with slow-release urea on milk production of Holstein dairy cows

The study investigated the effects of replacing soybean meal (SBM) with slow-release urea (SRU) on milk production, milk composition, and rumen fermentation of Holstein dairy cows. Sixteen Holstein cows weighing between 550 and 680 kg in mid lactation were randomly assigned to four dietary treatments in a 12-week study. The treatments consisted of T1: a diet containing 16.7% crude protein (CP), T2: T1 with 0.5% SRU replacing plant protein, T3: T1 with 0.75% SRU replacing plant protein, and T4: T1 with 1.00% SRU replacing plant protein. Animals were fed three times a day with feed being offered ad libitum. Dry matter intake (DMI) and average daily gain (ADG) were not affected by the level of SRU. Feeding SRU did not affect milk production and milk composition significantly, but milk fat and milk urea nitrogen (MUN) levels were increased. Significant differences were observed in ruminal volatile fatty acid (VFA) concentration. Feeding SRU increased butyrate concentration with no significant effects on concentrations of acetate or propionate. Significant differences were observed in cholesterol, triglyceride, high-density lipoprotein (HDL), low-density lipoprotein (LDL), and nonesterified fatty acid (NEFA) concentrations, but glucose, very-low-density lipoprotein (VLDL) and β-hydroxybutyrate (BHB) levels were not affected significantly by the treatments. Thus, feeding SRU altered the release rate of ammonia and provided more ammonia nitrogen (NH3-N) for microbial protein synthesis in the rumen.

Effect of exogenous dietary phytase and concentrate mixtures based on faba beans, rapeseed meal or soybean meal as main protein source on phytate and total phosphorus excretion in dairy cows

The aim of this study was to test the effect of exogenous dietary phytase on in vivo phytate P and total P excretion in dairy cows fed three different concentrate mixtures. Excretion and apparent total tract digestibility (ATTD) of phytate P and total P were measured in 24 Danish Holstein cows (18 multiparous and 6 primiparous), in early and mid-lactation. The cows were fed total mixed ration (TMR) with 60:40 forage to concentrate ratio. Three different concentrate mixtures were used, either with faba beans (FAB), rapeseed meal (RSM) or soybean meal (SBM) as the main protein source, constituting 270, 110 and 170 g/kg of dry matter (DM) in TMR, respectively. Addition of exogenous phytase enzyme was used to formulate 6 diets in a 3 × 2 factorial arrangement, used in a 6 × 4 incomplete balanced Latin square design with 4 periods. The six diets were formulated to be between 3.2 and 3.4 g P/kg of DM, below actual P recommendations (3.8 g P/kg of DM), and to have similar CP and Ca concentration. The main protein source accounted for 350−400 g/kg of total P supply. Obtained concentrations of P were 0.35 g/kg of DM higher than expected in RSM and SBM diets, and overall, intake of P was higher in cows fed RSM than in cows fed FAB and SBM diets. Cows fed RSM diets had lower P ATTD and excreted more P than cows fed FAB and SBM diets, likely because of a higher P intake. Cows fed FAB and SBM diets excreted similar amount of P, but cows fed SBM had higher P ATTD than cows fed FAB diet, indicating that P absorption was influenced by diet composition. Addition of phytase reduced phytate P excretion and increased phytate P ATTD independently of concentrate mixture in TMR. Addition of phytase tended to decrease faecal P concentration, tended to increase P ATTD and increased P balance in early lactation cows but not in mid lactation cows. This could have been caused by higher milk production and therefore higher P requirement in early latation cows than in mid lactation cows. Excess of dietary P reduced the effect of addition of phytase in mid-lactation cows, and possibly, to a lower extend, also in early lactation cows. Cows fed SBM had slightly lower dry matter intake than cows fed FAB and RSM, but no difference in milk production was observed between diets. Use of faba beans as main protein source can lower dietary P without compromising milk production, which can improve P digestibility and reduce P excretion.

Assessing feed efficiency in early and mid lactation and its associations with performance and health in Holstein cows

Objectives were to evaluate the associations between residual dry matter (DM) intake (RFI) and residual N intake (RNI) in early lactation, from 1 to 5 wk postpartum, and in mid lactation, from 9 to 15 wk postpartum, and assess production performance and risk of diseases in cows according to RFI in mid lactation. Data from 4 experiments including 399 Holsteins cows were used in this study. Intakes of DM and N, yields of milk components, body weight, and body condition were evaluated daily or weekly for the first 105 d postpartum. Milk yield by 305 d postpartum was also measured. Incidence of disease was evaluated for the first 90 d postpartum and survival up to 300 d postpartum. Residual DM and N intake were calculated in early and mid lactation as the observed minus the predicted values, which were based on linear models that accounted for major energy or N sinks, including daily milk energy or N output, metabolic body weight, and daily body energy or N changes, and adjusting for parity, season of calving, and treatment within experiment. Cows were ranked by RFI and RNI in mid lactation and categorized into quartiles (Q1 = smallest RFI, to Q4 = largest RFI). Increasing efficiency in mid lactation resulted in linear decreases in RFI (depicted from Q1 to Q4; -0.93, -0.05, -0.04, and 0.98 kg/d), DMI (16.0, 16.9, 17.3, and 18.4 kg/d), net energy for lactation (NEL) intake (26.8, 28.4, 29.0, and 30.8 Mcal/d), and NEL balance (-9.0, -8.1, -8.2, and -5.5 Mcal/d) during early lactation, but no differences were observed in body NEL or N changes or yield of energy-corrected milk in the first 5 wk of lactation. Residual DM intake in mid lactation was associated with RFI (Pearson r = 0.43, and Spearman ρ = 0.32) and RNI (r = 0.44, ρ = 0.36) in early lactation, and with RNI in mid lactation (r = 0.91, ρ = 0.84). Similarly, RNI in mid lactation was associated with RNI in early lactation (r = 0.42, ρ = 0.35). During the first 15 wk postpartum, more efficient cows in mid lactation consumed 3.5 kg/d less DM (Q1 = 19.3 vs. Q4 = 22.8 kg/d) and were more N efficient (Q1 = 31.6 vs. Q4 = 25.8%), at the same time that yields of milk (Q1 = 39.0 vs. Q4 = 39.4 kg/d), energy-corrected milk (Q1 = 38.6 vs. Q4 = 39.3 kg/d), and milk components did not differ compared with the quartile of least efficient cows. Furthermore, RFI in mid lactation was not associated with 305-d milk yield, incidence of diseases in the first 90 d postpartum, or survival by 300 d postpartum. Collectively, rankings of RFI and RNI are associated and repeatable across lactation stages. The most feed-efficient cows were also more N efficient in early and mid lactation. Phenotypic selection of RFI based on measurements in mid lactation is associated with improved efficiency without affecting production or health in dairy cows.

Physically effective neutral detergent fiber improves chewing activity, rumen fermentation, plasma metabolites, and milk production in lactating dairy cows fed a high-concentrate diet

Subacute ruminal acidosis (SARA) continues to be a common and costly metabolic disorder in high-producing dairy cows worldwide. The objective of this study was to evaluate if increasing the concentration of physically effective neutral detergent fiber (peNDF) in diets can reduce the risk of SARA in cows fed a high-concentrate diet. Thirty second-parity Holstein cows in mid lactation (131 ± 8.3 d in milk) were randomly allocated to 3 dietary treatments (10 dairy cows per group): high (11.3%, high peNDF8.0), medium (10.6%, medium peNDF8.0), or low (9.0%, low peNDF8.0) concentration of peNDF8.0. The diets were prepared by mixing the same total mixed ration (57% concentrate and 43% roughages) for 10, 18, or 60 min, respectively. The treatments were fed for 36 d with 21 d for adaptation and 15 d for sampling. The peNDF8.0 intake was positively correlated with the peNDF8.0 concentration. Chewing and ruminating times adjusted for dry matter intake and NDF intake were linearly increased with the increased dietary peNDF8.0 concentration. The high peNDF8.0 diet decreased the number of meals per day. The increased dietary peNDF8.0 concentration linearly increased the rumen fluid pH, the molar percentage of acetate and isobutyrate, acetate-to-propionate ratio, and ammonia nitrogen concentration, but linearly decreased the molar percentages of propionate and valerate. The total VFA concentration and the molar percentages of butyrate and isovalerate remained unchanged. Meanwhile, the increase in the peNDF8.0 concentration of the diet linearly increased the activities of carboxymethyl cellulase, avicelase, β-glucanase, and ferulic acid esterase in rumen fluid, but did not affect the activities of xylanase. Total plasma antioxidant capacity, γ-glutamyl transpeptidase activity, and plasma concentrations of total protein, albumin, creatinine, and malondialdehyde were linearly decreased by the increased dietary peNDF8.0 concentration. The increase in peNDF8.0 concentration raised the plasma concentrations of glucose, triglyceride, cholesterol, and blood urea nitrogen. Somatic cell counts in the milk were positively correlated with the dietary peNDF8.0 concentration. The feed and milk energy efficiencies were unaffected by the treatments. Shortening the total mixed ration mixing time may be a practical strategy to increase the peNDF8.0 concentration and reduce the risk of SARA in dairy cows fed high-concentrate diets.

Measuring liveweight changes in lactating dairy ewes with an automated walk-over-weighing system

Monitoring liveweight (LW) is an important part of sound management practices at the individual and flock level (e.g., controlling for nutritional status based on body condition, reproduction, and health-related issues), but it is time consuming and stressful. To our knowledge, no literature has reported on the evaluation of automated weighing systems in dairy sheep as an alternative to conventional static scales. The objective of this research was to evaluate the practical feasibility of using an automated walk-over-weighing (WoW) prototype to measure daily LW changes in dairy ewes without human intervention. We used adult Lacaune dairy ewes in 2 complementary trials conducted indoors. Trial 1 aimed at evaluating the repeatability, precision, and accuracy of LW measures recorded using WoW scales compared with a static scale (the gold standard). Forty-two adult ewes (LW ± standard deviation = 71.3 ± 10.4 kg) were randomly drafted from the main flock and used in a 1-day session. The trial included 3 passages. In each passage, ewes were weighed first on a static scale; once a static position was achieved and LW recorded, they continued the circuit and immediately traversed the WoW scale for an automated LW record. Trial 2 aimed to demonstrate the feasibility of using the WoW device under real-world conditions in a dairy sheep-farming system. The WoW scale was installed in the exit race of the milking parlor and evaluated over 7 wk with adult ewes in mid lactation (n = 93; LW 78.5 ± 8.1 kg). Once the ewes were acclimated to the WoW system, 1 group of ewes (n = 48) continued to receive the same feeding regimen (controls), and the other group (n = 45) underwent a nutritional challenge [challenged; 2 wk of undernutrition and then back to control regimen (refeeding) for 1 wk]. We evaluated the ability of the WoW to detect small changes in LW. We collected LW data (2 weighings per ewe per day) from the WoW after each of the 2 milking sessions (morning and evening). We also obtained LW values by weighing the ewes using a static scale once a week. The automated WoW system showed substantial agreement with the gold standard when assessed using Lin's concordance correlation coefficient and Bland and Altman's method, largely due to high repeatability. The WoW system was adequate for detecting small daily variations in LW during undernutrition and refeeding periods. Misbehaviors resulted in spurious WoW values in trial 2, requiring us to use filtration methods to exclude outlier weights and allow meaningful assessment of small LW changes. The WoW system evaluated here is an alternative to the static scales conventionally used on dairy sheep farms. If sound filtration of raw data is applied, WoW could contribute to the close (daily) monitoring of individual LW without operator intervention (i.e., voluntary weighing) and taking animal welfare into account (i.e., no stress related to the weighing session on static scales).

Feeding concentrates with different protein sources to high-yielding, mid-lactation Norwegian Red cows: Effect on cheese ripening

Soybean meal is one of the most important protein sources in concentrate feeds for dairy cows. The objective of the present study was to provide knowledge on the effects of using a novel yeast microbial protein source (Candida utilis) in concentrate feed for dairy cows on the production and quality of a Gouda-type cheese. Forty-eight Norwegian Red dairy cows in early to mid lactation were fed a basal diet of grass silage, which was supplemented with 3 different concentrate feeds. The protein source of the concentrates was based on conventional soybean meal (SBM), novel yeast (C. utilis; YEA), or barley (BAR; used as negative control because barley has a lower protein content). The experiment was carried out for a period of 10 wk, with the first 2 wk as an adaptation period where all dairy cows were fed grass silage and the SBM concentrate. The cows were then randomly allocated to 1 of the 3 different compound feeds: SBM, yeast, or barley. Cheeses were made during wk 8 and 9 of the experiment, with 4 batches of cheese made from milk from each of the 3 groups. The cheeses made from milk from cows fed SBM concentrate (SBM cheese) had a higher content of dl-pyroglutamic acid and free amino acids than the other cheeses, indicating a faster ripening in the SBM cheeses. Despite these differences, the sensory properties, the microbiota, and the Lactococcus population at 15 wk of ripening were not significantly different between the cheeses. This experiment showed that although the raw materials used in the concentrate feed clearly influenced the ripening of the cheeses, this did not affect cheese quality. Yeast (C. utilis) as a protein source in concentrate feed for dairy cows can be used as a replacement for soybean meal without compromising the quality of Norwegian Gouda-type cheeses.

Metabolic and hormonal control of energy utilization and partitioning from early to mid lactation in Sarda ewes and Saanen goats

In a recent study, we observed that starch-rich diets used in mid lactation induced lower milk production persistency and higher body fat accumulation in dairy ewes compared with dairy goats. Because these species differences could be linked to hormonal mechanisms that drive energy partitioning, in the same experiment, we explored the evolution of metabolic and hormonal status during lactation to test this hypothesis. Twenty mature Sarda dairy ewes and 20 mature Saanen goats [15-134 ± 11 d in milk (DIM), mean ± SD] were compared simultaneously. In early lactation, each species was allocated to one dietary treatment: high-starch diet [HS: 20.4% starch, on dry matter (DM) basis], whereas from 92 ± 11 DIM, each species was allocated to 1 of 2 dietary treatments: HS (20.0% starch, on DM basis) and low-starch (LS: 7.8% starch, on DM basis) diets. Blood samples were collected in the morning to analyze glucose, nonesterified fatty acids (NEFA), growth hormone (GH), insulin, and insulin-like growth factor I (IGF-I). Data were analyzed using the PROC MIXED procedure of SAS with repeated measurements (SAS Version 9.0). The HS and LS diets applied in mid lactation did not affect metabolic status of the animal within species; thus, only a comparison between species was carried out. From early to mid lactation, plasma glucose concentration was higher in ewes than in goats (54.57 vs. 48.35 ± 1.18 mg/dL), whereas plasma NEFA concentration was greater in goats than in ewes (0.31 vs. 0.25 ± 0.03 mmol/L). Goats had higher plasma GH concentration and lower plasma insulin content than ewes (4.78 vs. 1.31 ng/mL ± 0.47; 0.11 vs. 0.26 μg/L ± 0.02). Plasma IGF-I concentration did not vary between species. The comparison of metabolic and hormonal status of lactating Sarda dairy ewes and Saanen goats, carried out by studying simultaneously the 2 species in the same stage of lactation and experimental conditions, suggests that the higher insulin and glucose concentration observed in Sarda ewes explains why they partitioned more energy toward body reserves than to the mammary gland, especially in mid lactation. This can justify the negative effect of high-starch diets in mid-lactating Sarda ewes. Conversely, the highest GH and NEFA concentration observed in Saanen goats explain why they partitioned more energy of starch diets toward the mammary gland than to body reserves and justify the positive effect of high-starch diet in mid lactation. Together, these different responses contribute to explain why specialized dairy goats, such as the Saanen breed, have a higher milk production persistency than specialized dairy sheep breeds, such as the Sarda.

The influence of lactation stage on the milk constituents of Sahelian goats

Twelve lactating sahelian goals aged between 2 and 3 years and averaging 25kg body weight were selected from the herd of the University of Maiduguri Teaching and Research Farm, for a 19-week lactation study. The does were classified into early mid and late lactation stages and maintained daily on 1kg concentrate mixture per animal in addition to grazing on Gambia Grass. Milk collected were analysed for total solids (TS), butterfat, protein, solids-non-fat (SNF), Ash and energy. The mean percentage values (M+SE) of colostrum were TS 14.96 ± 0.41; butterfat 8.58±1.0; protein 5.64±0.31; ash 0.93±0.07; SNF 6.37±0.51; and energy 3.21 ± 0.39 MJ/kg. The overall mean values for mature milk were 13.18±0.27, 7.52±0.18, 4.81±0.14, 0.76±0.03, 5.66±0.16% and 2.79±0.12 MJ/KG respectively for TS. fat, protein, ash SNF and energy. There was a gradual decline in the values of all the components of colostrum from day 1-6 after kidding. Generally, colostrum constituents were higher in concentration than those of mature milk on the 7th day after parturition. The mature milk constituents tended to increase with advancing lactation. Milk constituents (especially Fat, Protein and SNF), as evident from this study could be manipulated through feeding.

Predicting Daily Dry Matter Intake Using Feed Intake of First Two Hours after Feeding in Mid and Late Lactation Dairy Cows with Fed Ration Three Times per Day.

Simple SummaryIt is difficult to obtain feed intake of dairy cows in experiments since all cows are raised in a free-stall barn in commercial dairy farms nowadays. Therefore, it is necessary to develop a simple, accurate, and reliable feed intake prediction model to replace direct measurement. In this study, we generated a forecasting model to predict daily dry matter intake (DMI) of dairy cows in mid and late lactation based on the feed intake of first 2 h after feeding (DMI-2h). The proposed prediction equation was: DMI (kg/day) = 8.499 + 0.2725 × DMI-2h (kg/day) + 0.2132 × Milk yield (kg/day) + 0.0095 × Body weight (kg/day) (R2 = 0.46). Compared with NRC model (2001), our model shows higher accuracy and precision on predicting daily DMI of dairy cows with fed ration three times per day in mid and late lactation period. This prediction model could be used as an alternative approach for researchers who have difficulty in measuring DMI in dairy cows’ experiments.The objective of this study was to evaluate the feasibility of using the dry matter intake of first 2 h after feeding (DMI-2h), body weight (BW), and milk yield to estimate daily DMI in mid and late lactating dairy cows with fed ration three times per day. Our dataset included 2840 individual observations from 76 cows enrolled in two studies, of which 2259 observations served as development dataset (DDS) from 54 cows and 581 observations acted as the validation dataset (VDS) from 22 cows. The descriptive statistics of these variables were 26.0 ± 2.77 kg/day (mean ± standard deviation) of DMI, 14.9 ± 3.68 kg/day of DMI-2h, 35.0 ± 5.48 kg/day of milk yield, and 636 ± 82.6 kg/day of BW in DDS and 23.2 ± 4.72 kg/day of DMI, 12.6 ± 4.08 kg/day of DMI-2h, 30.4 ± 5.85 kg/day of milk yield, and 597 ± 63.7 kg/day of BW in VDS, respectively. A multiple regression analysis was conducted using the REG procedure of SAS to develop the forecasting models for DMI. The proposed prediction equation was: DMI (kg/day) = 8.499 + 0.2725 × DMI-2h (kg/day) + 0.2132 × Milk yield (kg/day) + 0.0095 × BW (kg/day) (R2 = 0.46, mean bias = 0 kg/day, RMSPE = 1.26 kg/day). Moreover, when compared with the prediction equation for DMI in Nutrient Requirements of Dairy Cattle (2001) using the independent dataset (VDS), our proposed model shows higher R2 (0.22 vs. 0.07) and smaller mean bias (−0.10 vs. 1.52 kg/day) and RMSPE (1.77 vs. 2.34 kg/day). Overall, we constructed a feasible forecasting model with better precision and accuracy in predicting daily DMI of dairy cows in mid and late lactation when fed ration three times per day.

Impact of Parity Order on Nutritional Values of Camel Milk in Modern System

Camel milk has important role in human nutrition in desert and semi-desert regions; this milk provides the man with all essential nutrients in addition to its medicinal properties. A study was conducted to determine the impact of parity order on nutrition values of camel milk overall four months postpartum under modern system. Eight she-camels were selected immediately after calving and assigned to two equal groups, early lactation (GY) and mid lactation (GD). Both groups were managed together at the same environmental conditions under intensive system. Collection of milk samples started at second week postpartum and continued biweekly interval up to end of 4th month postpartum. The total fat, protein, lactose, solid non-fat (SNF) and density percentages were determined by automatic milk analyzer device (lactoscan Model-90, Europe). Results elucidated that there was no significant difference of lactose and fat content between two groups throughout experiment period. Where the significant difference (P˂0.05) of protein, SNF and density contents of milk were detected during lactation stages throughout four months. Otherwise, the levels of fat, lactose, protein and SNF were increased significantly (P˂0.05) with advancement of lactation stage, beside fluctuation of density values during experiment period. The current study revealed that milk produced by young is slightly richer in fat content, whereas milk of old camel is richer in protein content. The variation of nutrition values of milk should be attributed to parities, calve number and physiological factors.

Energetic parameters in pregnant and lactating rat (Lasiopodomys brandtii) fed high- or low-fibre diets

The effect of diet quality (high-fibre (HF) or low-fibre (LF)) on energetic parameters in pregnant and lactating rats (Lasiopodomys brandtii) was examined. There was no significant difference (p&gt;0.05) in body mass of voles prior to dietary acclimation and during pregnancy. Energetic parameters (dry matter, gross energy, digestible energy intake and digestibility) as well as body mass of pups was not significantly (p&gt;0.05) affected by diet quality. Low fibre diet caused a decreased (p&lt;0.05) in feed and gross energy intake and increased (p&lt;0.001) digestible energy intake at mid lactation while digestibility was significantly increased at early lactation. Liver and kidney were significantly (p&lt;0.05) lighter in voles on low fibre diet. No significant difference was observed between diets for metabolic rate. These results revealed that rats can compensate for poor quality (HF) diet physiologically by increasing food intake and decreasing digestible energy intake and digestibility to keep reproductive performance unaffected. The most energetically demanding period of breeding cycle of rat was mid lactation.

Comparative evaluation of lactation performance of West African dwarf and red sokoto goats raised in a hot-humid environment

The milk yield and compositions of twelve lactating does comprising six each of West African Dwarf (Fouta djallon) and Red Sokoto (Maradi) were compared in a 21-week study. The does in their second parity were monitored over a full lactation. The goats received daily basal grass and browse fodder in addition to a concentrate supplement in a 2 × 3 factorial experiment. The does were hand milked and milk yield (g/d) was quantified daily. Milk samples were analyzed weekly for total solids (TS %), butter fat (BF %), solids-not-fat (SNF %), crude protein (CP %) and total ash (TA %). Lactose concentration (LC %) was analyzed daily immediately after sampling. Macro-minerals in milk samples were determined by dry ash extraction method specific for each mineral element. Milk yield was influenced significantly (p&lt;0.05) by both breed and stage of lactation. The WAD produced more milk (97.34 g/d than RS (87.01 g/d). For both breeds, the average mid lactation milk yield (119.04 g/d) was significantly (p&lt;0.05) different than either early (88.35 g/d) or late (69.14 g/d). The highest milk production was by WAD does in mid lactation (125.10 g/d) and the least was by RS in late lactation (47.07 g/d). The TS, BF, SNF, CP and LC concentrations in milk were not influenced (P&gt;0.05) by breed. The TA was significantly (P&lt;0.05) higher in WAD milk (0.89 %) relative to RS milk (0.88 %). Also, stage of lactation significantly (P&lt;0.05) influenced the concentrations of TS, BF, TA and LC in WAD and RS goats milk. Total solids was significantly (P&lt;0.05) higher in late (13.47 %) than in early (12.53 %) lactation for both breeds. The BF and LC in milk followed similar trend, recording 4.45, 3.89 and 4.13 and 3.98 % in late and early stages of lactation respectively. On the other hand, The TA decreased with advancing lactation and the highest value was obtained in the early (0.92 %) than in mid (0.89 %) and late (0.86 %) lactation in both WAD and RS goat milk. TA was highest in WAD milk in early lactation (0.92 %) and least in RS milk in late lactation (0.85 %). All macro minerals were influenced (p&lt;0.05) by lactation stage and breed differences, except potassium (K) and sodium (Na) which were only influenced by the stage of lactation. The milk of both WAD and RS goats yielded more calcium (Ca) than K, which was attributed to the nutrients in the diets.