Seasonal variations of physiological responses, milk production, and fatty acid profile of local crossbred cows in Tunisia.

The study investigates the seasonal variations of physiological responses, milk yield, milk composition, and milk fatty acid profile of local crossbred cows (Friesian × Brown Atlas) in northwestern Tunisia. A total of 80 multiparous cows from smallholder farmers were sampled between 2018 and 2019. The cows were feed the same diet ad libitum and exposed to the same Mediterranean climatic conditions. Weekly rectal temperature (RT; °C), respiratory rate (RR; rpm), and heart rate (HR; bpm) were measured per cow in each season. Individual milk yield and samples were recorded bi-weekly and collected in duplicate for chemical analyses. Milk fatty acids (FAs) were analyzed using gas chromatography-mass spectrometry (GC-MS). Results showed an increase (P < 0.05) in RT (+ 1.3%), RR (+ 12.1%), and HR (+ 9.9%) when the temperature-humidity index (THI) increased from winter (53.6) to summer (74.4) in response to heat stress. Milk yield did not vary significantly between seasons (8.3 L/day on average). Summer milk contained more fat (+ 7.8%) and log SCC (+ 13.7%). The proportion of the monounsaturated (31.2 vs. 27.2%) and polyunsaturated (4.29 vs. 3.86%) FAs decreased (P < 0.05) between winter and summer. Saturated FAs (64.5 vs. 67.7%) were higher (P < 0.05) in summer than in winter. Winter milk fat contained higher levels of C18:2cis-9 trans-11 (CLA) (0.73 vs. 0.56%) and ω-3 FA (0.83 vs. 0.63%), but a lower ω-6/ω-3 ratio (4.07 vs. 6.17%) compared to summer. As the cows were fed the same diet throughout the two seasons, the performances obtained were mainly due to the resistance of the local crossbred cow to the hot conditions. It is concluded that the local crossbred cow maintains its productivity and tolerate the hot Mediterranean climate.

Responses to melatonin of 2 breeds of dairy ewes in early lactation under autumn photoperiod conditions.

A total of 72 dairy ewes of 2 breeds (MN, Manchega, 72.4 ± 1.9 kg of body weight, n = 36; LC, Lacaune, 77.7 ± 2.3 kg of body weight; n = 36) were used to evaluate the lactational effects of melatonin implants in early lactation and under the short-day photoperiod conditions of autumn (experiment was centered on the winter solstice). Ewes lambed in autumn and were penned indoors in 12 balanced groups of 6 ewes by breed, body weight, age, and number of lambs, and randomly assigned to a 2 × 2 × 3 factorial design (treatment × breed × replicate). Ewes suckled their lambs for 28 d. Treatments were (1) melatonin (MEL), which received 1 subcutaneous implant of melatonin (18 mg/ewe) in the ear base at 35 ± 1 d (1 wk after lamb weaning), and (2) control, which did not receive any treatment. Ewes were fed ad libitum a total mixed ration (forage:concentrate, 60:40) and machine milked twice daily. Daily milk yield was automatically recorded from d 29 to 105 of lactation and sampled every 2 wk for composition. Jugular blood was sampled for plasma hormone analyses at 30, 50, 80, 110, and 124 d of lactation. Body reserves were assessed every 2 wk. Feed intake was measured by pen during 3 separated periods after the start of the treatments (wk 2 to 3, wk 6 to 7, and wk 10 to 11). Feed intake, and milk yield and composition varied by breed, but no MEL effects were detected on dry matter intake, milk yield, milk composition, or fat and protein standardized milk in either breed. As a result of the unique composition of the implants and the variable body weights of the ewes, the MEL treatment dose (on average, 0.24 mg/kg of body weight) was 6.8% greater in the MN (lighter) than in the LC (heavier) ewes. Plasmatic melatonin markedly increased in the MEL-treated ewes (on average, 111%), but despite the amount of MEL used, the MN responded greatly compared with the LC ewes (150 vs. 63%, respectively). No differences in basal plasmatic melatonin were detected between breeds (6.4 ± 1.1 pg/mL, on average), indicating the greater responsiveness to the implants of the lighter MN ewes. Plasmatic prolactin tended to decrease in the MEL-treated ewes (-35%, on average), but the effect was significant only in the MN ewes (-54%), in agreement with their greater response to MEL. No effects of MEL treatment were detected on plasmatic IGF-I in either breed. Moreover, body reserves did not vary by effect of MEL treatment or breed throughout the experiment. In conclusion, the use of exogenous melatonin as MEL implants, together with the endogenous melatonin naturally produced under short-day photoperiod conditions, had no effects on the early-lactation performances of dairy sheep, despite their breed and level of production.

Suppression of prolactin and reduction of milk secretion by effect of cabergoline in lactating dairy ewes.

The effects of cabergoline, an ergot derivative and dopamine receptor agonist, were investigated in 30 ewes of 2 dairy breeds (Manchega; MN, n = 15; Lacaune; LC, n = 15). Ewes were in a similar late-lactation stage, but differed in milk yield according to breed (MN vs. LC, 1.02 ± 0.03 vs. 2.27 ± 0.05 kg/d). Treatments consisted of a single intramuscular injection of cabergoline at different doses per ewe. Cabergoline doses (per ewe) were: low (0.56 mg), high (1.12 mg), and control (CON; 0 mg; 1 mL of saline). Milk yield was recorded daily (d -14 to 25), milk and blood were sampled, and udder traits were measured from d -2 to 14 after injection. No local reaction at the injection site, nor behavior and metabolic indicators of the ewes were detected after the cabergoline injection, but milk yield fell rapidly in both breeds (MN vs. LC, -54% vs. -27%) when compared with CON ewes. Cabergoline effects progressively disappeared after d 5, and no milk yield differences between treatments were detected from d 8 to 25 after injection. Milk fat and protein contents increased similarly (22% and 23%; respectively) in both breeds and at both cabergoline doses until d 5, and the effects disappeared thereafter. Plasma prolactin (PRL) decreased dramatically in the low- and high-treated ewes the day after injection when compared with the CON ewes, and reached values below the detection limit of the assay between d 1 and 5, increasing similarly thereafter. On d 14, PRL values were 58% greater in the low- and high-treated than in the CON ewes, showing that PRL concentrations rebounded when the cabergoline effects ceased. Total udder volume correlated with milk accumulated in the udder (r = 0.77) of all groups of ewes throughout the experiment, suggesting its use as a noninvasive method for the estimation of milk stored in the udder. Udder volume was similar for the low and high ewes, but both values were lower than those of the CON ewes from d 1 to 14 after injection. No other effects on udder size were detected. Cabergoline dramatically inhibited PRL secretion and decreased milk yield and udder volume of lactating dairy ewes. The low dose of cabergoline was as effective as the high dose in the 2 breeds of dairy ewes. These results suggest the use of cabergoline to facilitate the decrease of milk production in dairy ewes (e.g., dry-off, illness care), although further research in pregnant dairy ewes and during the following lactation is still needed.

Enhanced supply of methionine or arginine alters mechanistic target of rapamycin signaling proteins, messenger RNA, and microRNA abundance in heat-stressed bovine mammary epithelial cells in vitro.

Heat stress (HS) causes reductions in milk production, but it is unclear whether this effect is due to reduced number or functional capacity (or both) of mammary cells. Methionine supplementation improves milk protein, whereas Arg is taken up in excess by mammary cells to produce energy and nonessential AA that can be incorporated into milk protein. To evaluate molecular mechanisms by which mammary functional capacity is affected by HS and Met or Arg, mammary alveolar (MAC-T) cells were incubated at thermal-neutral (37°C) or HS (42°C) temperatures. Treatments were optimal AA profiles (control; Lys:Met = 2.9:1.0; Lys:Arg = 2.1:1.0), control plus Met (Lys:Met = 2.5:1.0), or control plus Arg (Lys:Arg = 1.0:1.0). After incubation for 6 h, cells were harvested and RNA and protein were extracted for quantitative real-time PCR and Western blotting. Protein abundance of mechanistic target of rapamycin (MTOR), eukaryotic initiation factor 2a, serine-threonine protein kinase (AKT), 4E binding protein 1 (EIF4EBP1), and phosphorylated EIF4EBP1 was lower during HS. The lower phosphorylated EIF4EBP1 with HS would diminish translation initiation and reduce protein synthesis. Both Met and Arg had no effect on MTOR proteins, but the phosphorylated EIF4EBP1 decreased by AA, especially Arg. Additionally, Met but not Arg decreased the abundance of phosphorylated eukaryotic elongation factor 2, which could be positive for protein synthesis. Although HS upregulated the heat shock protein HSPA1A, the apoptotic gene BAX, and the translation inhibitor EIF4EBP1, the mRNA abundance of PPARG, FASN, ACACA (lipogenesis), and BCL2L1 (antiapoptotic) decreased. Greater supply of Met or Arg reversed most of the effects of HS occurring at the mRNA level and upregulated the abundance of HSPA1A. In addition, compared with the control, supply of Met or Arg upregulated genes related to transcription and translation (MAPK1, MTOR, SREBF1, RPS6KB1, JAK2), insulin signaling (AKT2, IRS1), AA transport (SLC1A5, SLC7A1), and cell proliferation (MKI67). Upregulation of microRNA related to cell growth arrest and apoptosis (miR-34a, miR-92a, miR-99, and miR-184) and oxidative stress (miR-141 and miR-200a) coupled with downregulation of fat synthesis-related microRNA (miR-27ab and miR-221) were detected with HS. Results suggest that HS has a direct negative effect on synthesis of protein and fat, mediated in part by coordinated changes in mRNA, microRNA, and protein abundance of key networks. The positive responses with Met and Arg raise the possibility that supplementation with these AA during HS might have a positive effect on mammary metabolism.

Effects of shearing 2 breeds of dairy ewes during lactation under mild winter conditions.

The lactational effects of shearing (CO, control unshorn; SH, shorn) were investigated in 48 dairy ewes of 2 breeds (Lacaune, LC, n = 24; Manchega, MN, n = 24) having a similar stage of lactation (120 ± 6 d in milk) and body frame (65.1 ± 1.5 kg of body weight and 2.4 ± 0.1 body condition score), but differing in fleece and milk production. Ewes were penned indoors, adapted to the diet (alfalfa hay ad libitum and fixed amount of concentrate), and allocated for 30 d in 8 balanced groups to which the experimental treatments were applied. All ewes were sheared on the same day. Feed intake by pen and milk yield by ewe were recorded daily. Individual samples of milk (d -3, 3, 5, 7, and 15) and blood (d -7, 3, 7, and 15) were collected, as well as body weight and body condition score measured (d -15, 0, and 15), related to shearing. Pooled milk samples per pen were also collected before and after shearing for milk fatty acid analysis (d -3 and 15). Average temperatures in the barn before (12.6 ± 0.7°C) and after (13.7 ± 0.4°C) shearing were mild. Fleece was heavier in MN than in LC (1.04 ± 0.10 vs. 0.75 ± 0.09 kg/ewe) and tended to cover more body surface in MN than in LC ewes. Responses to shearing varied according to breed, the rectal temperature after shearing only decreasing significantly in the MN (-0.36 ± 0.09°C). Feed intake increased in the LC-SH (5%), when compared with LC-CO, but did not vary in the MN ewes. Ingestibility of the alfalfa hay, expressed as filling units for sheep and monitored in 2 groups of 6 dry and unshorn ewes of each breed (73.0 ± 2.5 kg of body weight and 3.1 ± 0.2 body condition score), was constant throughout the experiment (0.99 ± 0.03 filling units for sheep/kg of dry matter). Regarding milk production, LC-SH ewes yielded 10% more milk (1.38 ± 0.06 vs. 1.52 ± 0.05 kg/d) than LC-CO ewes, but no differences were detected in MN ewes (0.74 ± 0.03 kg/d, on average). No differences in the concentration of major milk components by effect of the shearing treatment were detected in either breed, but LC-SH ewes yielded 9% more milk protein than did LC-CO ewes. No relevant effects of shearing were detected on milk fatty acid profiles, although MN ewes showed lower C4:0, C6:0, C14:0, trans-11 and trans-12 C18:1 contents than did LC ewes. Moreover, no changes by effect of shearing were detected in plasma glucose, nonesterified fatty acids, cortisol, or insulin values in either breed, or in body weight or body condition score. In conclusion, shearing dairy ewes during lactation under mild winter conditions is a suitable management option that may increase feed intake and milk production, without deleterious effects on milk composition.

Using wireless rumen sensors for evaluating the effects of diet and ambient temperature in nonlactating dairy goats.

Sixteen Murciano-Granadina dairy goats, provided with wireless rumen sensors for pH and temperature, were used to assess the rumen environment variations produced by extreme forage to concentrate diets (experiment 1) and climatic conditions (experiment 2). To avoid the interference of feed intake, goats were fed at maintenance level. Rumen sensors were inserted by surgery and programmed to collect and store rumen pH and temperature every 30min. In experiment 1, 8 dry goats (38.6±2.3kg of body weight) in tiestalls were divided into 2 groups and fed at maintenance level with 2 diets varying in forage-to-concentrate ratio [high forage (HF) 70:30; low forage (LF) 30:70] according to a crossover design. Diets were offered once daily for 4h and tap water (4 L, 9.8±0.4°C) was offered for only 30min at 6h after feeding. Rectal temperatures were recorded 3 times during the day. Rumen pH fell immediately after feeding, reaching a nadir depending on the diet (HF=6.35±0.07 at 11h after feeding; LF=6.07±0.07 at 6h after feeding) and being on average greater (0.31±0.06) in HF than LF goats. No diet effects were detected in rectal (38.2±0.1°C) and ruminal (38.9±0.1°C) mean temperatures, which were positively correlated. Rumen temperature dramatically changed by feeding (1.4±0.1°C) and drinking (-3.4±0.1°C), and 2h were necessary to return to the fasting value (38.2±0.1°C). In experiment 2, 8 dry goats (43.9±1.0kg of body weight) were kept in metabolic cages, fed a 50:50 diet and exposed to 2 climatic conditions following a crossover design. Conditions were thermoneutral (TN; 20 to 23°C day-night) and heat stress (HS; 12-h day at 37°C and 12-h night at 30°C). Humidity (40±5%) and photoperiod (light-dark, 12-12h) were similar. Goats were fed at maintenance level, the feed being offered once daily and water at ambient temperature was freely available. Intake, rectal temperature, and respiratory rate were recorded 3 times daily. Despite no differing in dry matter intake, rumen pH was lower in HS than in TN goats (-0.12±0.04). On the contrary, rumen temperature (0.3±0.1°C), rectal temperature (0.4±0.1°C), respiratory rate (77±5 breaths/min), and water intake (3.2±0.7 L/d) had a greater increase in HS than TN, which might indicate an altered microbial fermentation under high temperature conditions. In conclusion, wireless bolus sensors proved to be a useful tool to monitor rumen pH and temperature as affected by different feeding and climatic conditions.

Implementing electronic identification for performance recording in sheep: I. Manual versus semiautomatic and automatic recording systems in dairy and meat farms.

With the aim of assessing the secondary benefits of using electronic identification (e-ID) in sheep farms, we compared the use of manual (M), semiautomatic (SA), and automatic (AU) data-collection systems for performance recording (i.e., milk, lambing, and weight) in 3 experiments. Ewes were identified with visual ear tags and electronic rumen boluses. The M system consisted of visual ear tags, on-paper data recording, and manual data uploading to a computer; the use of a personal digital assistant (PDA) for data recording and data uploading was also done in M. The SA system used a handheld reader (HHR) for e-ID, data recording, and uploading. Both PDA and HHR used Bluetooth for uploading. The AU system was only used for body weight recording and consisted of e-ID, data recording in an electronic scale, and data uploading. In experiment 1, M and SA milk-recording systems were compared in a flock of 48 dairy ewes. Ewes were milked once- (×1, n=24) or twice- (×2, n=24) daily in a 2 × 12 milking parlor and processed in groups of 24. Milk yield (1.21 ± 0.04 L/d, on average) was 36% lower in ×1 than ×2 ewes and milk recording time correlated positively with milk yield (R(2)=0.71). Data transfer was markedly faster for PDA and HHR than for M. As a result, overall milk recording time was faster in SA (×1=12.1 ± 0.6 min/24 ewes; ×2=22.1 ± 0.9 min/24 ewes) than M (×1=14.9 ± 0.6 min/24 ewes; ×2=27.9 ± 1.0 min/24 ewes). No differences between PDA and HHR were detected. Time savings, with regard to M, were greater for ×2 than for ×1 (5.6 ± 0.2 vs. 2.8 ± 0.1 min per 24 ewes, respectively), but similar for PDA and HHR. Data transfer errors averaged 3.6% in M, whereas no errors were found in either SA system. In experiment 2, 73 dairy and 80 meat ewes were monitored at lambing using M and SA. Overall time for lambing recording was greater in M than SA in dairy (1.67 ± 0.06 vs. 0.87 ± 0.04 min/ewe) and meat (1.30 ± 0.03 vs. 0.73 ± 0.03 min/ewe) ewes. Recording errors were greater in dairy (9.6%) than in meat (1.9%) ewes. Data uploading errors only occurred in M (4.9%). In experiment 3, 120 dairy and 120 meat ewes were weighed using M and AU systems. In both flocks, mean BW recording and data uploading times, as well as overall BW recording time (0.63 ± 0.02 and 0.25 ± 0.01 min/ewe, respectively) were greater in M than in AU, and uploading errors only occurred in M (8.8%). In conclusion, HHR and PDA systems were time-effective for performance recording, both saving time and improving data accuracy. Working load and time for ewe identification were faster in HHR but it did not affect the performance recording time. The PDA was the fastest device for data download. Further research will evaluate the costs of implementing e-ID for performance recording and other uses in sheep farms.

Implementing electronic identification for performance recording in sheep: II. Cost-benefit analysis in meat and dairy farms.

Costs and secondary benefits of implementing electronic identification (e-ID) for performance recording (i.e., lambing, body weight, inventory, and milk yield) in dairy and meat ewes were assessed by using the results from a previous study in which manual (M), semiautomatic (SA), and automatic (AU) data collection systems were compared. Ewes were identified with visual ear tags and electronic rumen boluses. The M system used visual identification, on-paper data recording, and manual data uploading to a computer. The SA system used e-ID with a handheld reader in which performances were typed and automatic uploaded to a computer. The use of a personal digital assistant (PDA) for recording and automatic data uploading, which transformed M in a SA system, was also considered. The AU system was only used for BW recording and consisted of e-ID, automatic data recording in an electronic scale, and uploading to a computer. The cost-benefit study was applied to 2 reference sheep farms of 700 meat ewes, under extensive or intensive production systems, and of 400 dairy ewes, practicing once- or twice-a-day machine milkings. Sensitivity analyses under voluntary and mandatory e-ID scenarios were also included. Benefits of using e-ID for SA or AU performance recording mainly depended on sheep farm purpose, number of test days per year, handheld reader and PDA prices, and flock size. Implementing e-ID for SA and AU performance recording saved approximately 50% of the time required by the M system, and increased the reliability of the data collected. Use of e-ID increased the cost of performance recording in a voluntary e-ID scenario, paying only partially the investment made (15 to 70%). For the mandatory e-ID scenario, in which the cost of e-ID devices was not included, savings paid 100% of the extra costs needed for using e-ID in all farm types and conditions. In both scenarios, the reader price was the most important extra cost (40 to 90%) for implementing e-ID in sheep farms. Calculated extra costs of using the PDA covered more than 100% of the implementation costs in all type of sheep farms, indicating that this device was cost-effective for sheep-performance recording.

Thermographic variation of the udder of dairy ewes in early lactation and following an Escherichia coli endotoxin intramammary challenge in late lactation.

A total of 83 lactating dairy ewes (Manchega, n=48; Lacaune, n=35) were used in 2 consecutive experiments for assessing the ability of infrared thermography (IRT) to detect intramammary infections (IMI) by measuring udder skin temperatures (UST). In experiment 1, ewes were milked twice daily and IRT pictures of the udder were taken before and after milking at 46 and 56d in milk (DIM). Milk yield was 1.46 ± 0.04 L/d, on average. Detection of IMI was done using standard bacterial culture by udder half at 15, 34, and 64 DIM. Twenty-two ewes were classified as having IMI in at least one udder half, the others being healthy (142 healthy and 24 IMI halves, respectively). Four IMI halves had clinical mastitis. No UST differences were detected by IMI and udder side, being 32.94 ± 0.04°C on average. Nevertheless, differences in UST were detected for breed (Lacaune - Manchega=0.35 ± 0.08°C), milking process moment (after - before=0.13 ± 0.11°C), and milking schedule (p.m. - a.m.=0.79 ± 0.07°C). The UST increased linearly with ambient temperature (r=0.88). In experiment 2, the UST response to an Escherichia coli O55:B5 endotoxin challenge (5 µg/udder half) was studied in 9 healthy Lacaune ewes milked once daily in late lactation (0.58 ± 0.03 L/d; 155 ± 26 DIM). Ewes were allocated into 3 balanced groups of 3 ewes to which treatments were applied by udder half after milking. Treatments were (1) control (C00, both udder halves untreated), (2) half udder treated (T10 and C01, one udder half infused with endotoxin and the other untreated, respectively), and (3) treated udder halves (T11, both udder halves infused with endotoxin). Body (vaginal) temperature and UST, milk yield, and milk composition changes were monitored by udder half at different time intervals (2 to 72 h). First local and systemic signs of IMI were observed at 4 and 6h postchallenge, respectively. For all treatments, UST increased after the challenge, peaking at 6h in T 0055 (which differed from that in C00, C01, and T10), and decreased thereafter without differences by treatment. Vaginal temperature and milk somatic cell count increased by 6h postchallenge, whereas lactose content decreased, in the endotoxin-infused udder halves. Effects of endotoxin on lactose and somatic cell count values were detectable in the infused udder halves until 72 h. In conclusion, despite the accuracy of the camera (± 0.15°C) and the moderate standard errors of the mean obtained for UST measures (± 0.05 to 0.24°C), we were unable to discriminate between healthy and infected (subclinically or clinically) udder halves in dairy ewes.

Identifying the major bacteria causing intramammary infections in individual milk samples of sheep and goats using traditional bacteria culturing and real-time polymerase chain reaction.

Use of DNA-based methods, such as real-time PCR, has increased the sensitivity and shortened the time for bacterial identification, compared with traditional bacteriology; however, results should be interpreted carefully because a positive PCR result does not necessarily mean that an infection exists. One hundred eight lactating dairy ewes (56 Manchega and 52 Lacaune) and 24 Murciano-Granadina dairy goats were used for identifying the main bacteria causing intramammary infections (IMI) using traditional bacterial culturing and real-time PCR and their effects on milk performance. Udder-half milk samples were taken for bacterial culturing and somatic cell count (SCC) 3 times throughout lactation. Intramammary infections were assessed based on bacteria isolated in ≥2 samplings accompanied by increased SCC. Prevalence of subclinical IMI was 42.9% in Manchega and 50.0% in Lacaune ewes and 41.7% in goats, with the estimated milk yield loss being 13.1, 17.9, and 18.0%, respectively. According to bacteriology results, 87% of the identified single bacteria species (with more than 3 colonies/plate) or culture-negative growth were identical throughout samplings, which agreed 98.9% with the PCR results. Nevertheless, the study emphasized that 1 sampling may not be sufficient to determine IMI and, therefore, other inflammatory responses such as increased SCC should be monitored to identify true infections. Moreover, when PCR methodology is used, aseptic and precise milk sampling procedures are key for avoiding false-positive amplifications. In conclusion, both PCR and bacterial culture methods proved to have similar accuracy for identifying infective bacteria in sheep and goats. The final choice will depend on their response time and cost analysis, according to the requirements and farm management strategy.

Physiological responses and lactational performances of late-lactation dairy goats under heat stress conditions.

Eight Murciano-Granadina dairy goats in late lactation were exposed to different ambient conditions, using metabolic cages in a climatic chamber. The experimental design was a crossover (2 periods of 35 d and 4 goats each) and conditions were (1) thermal neutral (TN; 15 to 20 °C day-night) and (2) heat stress (HS; 12-h day at 37 °C and 12-h night at 30.5 °C). Humidity was maintained at 40% and light-dark was constant (12-12h). The forage:concentrate ratio was adjusted daily for maintaining similar value in TN and HS goats (70:30). Water was freely available at ambient temperature. Rectal temperature and respiratory rate (0800, 1200 and 1700 h) and milk yield were recorded daily, whereas milk composition, nonesterified fatty acids and haptoglobin in blood were analyzed weekly. At d 25, additional blood samples were taken for analysis of metabolites and indicators of the acid-base balance. Digestibility coefficients and N balance were determined (d 31 to 35) and body weight was recorded (d 35). Compared with TN goats, HS goats experienced greater rectal temperature (+0.58 °C), respiratory rate (+48 breaths/min), water intake (+77%) and water evaporation (+207%). Intake of HS goats rapidly declined until d 7 (-40%), partially recovered from d 7 to 19, and steadied thereafter (-14%). No changes in digestibility or N balance were detected. Blood nonesterified fatty acids and haptoglobin peaked at d 7 in HS goats but did not vary thereafter. Although milk yield did not vary by treatment, milk of HS goats contained -12.5% protein and -11.5% casein than TN goats. Panting reduced concentration and pressure of CO2 in the blood of HS goats, but they were able to maintain their blood pH similar to the TN group by lowering HCO3(-) and increasing Cl(-) concentrations in their blood. In conclusion, HS dairy goats showed dramatic physiological changes during the first week of treatment and partially recovered thereafter. They were able to maintain milk yield by losing body mass, but milk protein content and protein yield were depressed. Further research is needed to assess the response of dairy goats to HS at earlier stages of lactation.

When to shear dairy ewes: before breeding, during pregnancy or let them unshorn?

Shearing dairy ewes may improve their fitness and heat tolerance during late pregnancy, with positive effects on lambs and lactation performances. To test this hypothesis, two Mediterranean breeds (MN, Manchega, n = 43; LC, Lacaune, n = 28), differing in lactation performances and fleece traits, were submitted to three shearing strategies: (i) shorn before breeding (SBB), (ii) shorn at day 100 of pregnancy (S100) and (iii) unshorn (CO). Ewes were bred in spring and gestated during summer. Fleece traits and respiratory rate were measured on pregnant (107-121 days) resting ewes at different barn temperatures. Blood and colostrum were sampled at lambing. Ewes suckled their lambs (28 days) and were machine-milked until 180 days of lactation. Lamb and ewe weights, and condition score of the ewes, were recorded throughout the experiment. Milk yield was assessed during suckling (fortnightly) and milking (daily), and milk was sampled for composition (fortnightly). Fleece extension and wool weight at S100 were 13 and 45% greater in MN than in LC ewes, respectively, but the ewe's respiration rate at late pregnancy, between 20 and 25 °C, did not vary among shearing treatments nor breeds. Nevertheless, S100 ewes had a 37% lower respiration rate than SBB and CO ewes at 28 °C. At lambing, SBB and S100 ewes had 86% higher glycaemia than CO in MN, but LC ewes did not vary. Shearing treatment had no effect in plasma insulin, ß-hydroxybutyrate or non-esterified fatty acids (NEFAs) at lambing in both breeds. Lamb's birthweight and growth during suckling did not differ by shearing treatment in both breeds. Colostrum composition and milk yield during suckling were not modified by shearing treatment in either breed, although S100 suckling milk composition increased in MN (protein and casein, 6%) and LC ewes (total solids, 8%; fat, 18%), compared to CO and SBB. No effects were detected in milk yield or composition during milking, but S100 tended to yield 28% more milk than CO in the LC ewes. The S100 treatment improved the body reserves in late pregnancy, when compared to CO and SBB in both breeds. In conclusion, shearing dairy ewes in late pregnancy was a recommendable management practice under summer conditions, because alleviated heat stress and improved the weight of the ewes, without detrimental effects on lambing and lactational performances, the last tending to increase milk yield in high-yielding dairy ewes.

Modeling the retention of rumen boluses for the electronic identification of goats.

We constructed a regression model to estimate the retention of electronic boluses in goats. With this aim, 2,482 boluses were administered to goats from dairy (Murciano-Granadina, n=1,326; French Alpine, n=381) and meat (Blanca de Rasquera, n=532) breeds. A total of 19 bolus types made of materials (ceramic, plastic tubes filled with concrete or silicone, and ballasts) differing in their specific gravity (SG) were used, thereby obtaining a wide variation in bolus features: diameter (9 to 22 mm), length (37 to 84 mm), weight (5 to 111 g), volume (2.6 to 26 mL), and SG (1.0 to 5.5). Each bolus contained a half-duplex glass encapsulated transponder (32 × 3.8mm) and was administered using adapted balling guns. Murciano-Granadina and Blanca de Rasquera goats also wore 2 visual plastic ear tags: V1 (double flag, 5.1g) and V2 (flag-button, 4.2g). No data on ear tags in French Alpine goats was available. Bolus and ear tag retention [(retained/monitored) × 100] was recorded for at least 1 yr. Dynamic reading efficiency [(dynamic reading/static reading) × 100] was also evaluated from 1,496 bolus readings. No administration incidences or apparent negative behavior or performance effects were observed for any bolus type. Static reading efficiency of retained boluses was 100%, except for the prototypes with metal ballasts, which yielded a 93.3% reading efficiency. Retention of metal-ballasted boluses was confirmed using x-ray equipment. Excluding ballasted boluses, a 99.5% dynamic reading efficiency was obtained. Ear tag losses were 6.5% for V1 and 3.7% for V2, ranging from 3.2 to 7.8% depending on ear tag type and goat breed. Bolus retention varied (0 to 100%) according to their physical features. Obtained data allowed the fitting of a logistic model of bolus retention rate according to bolus volume and weight (R(2) = 0.98); the SG was implicitly considered. Estimated weight and SG to produce medium- (15 mL) and standard-sized (22 mL) boluses for 99.95% retention rate in goats were 73.0 and 94.1g, and 4.87 and 4.28, respectively. Mini-boluses are not recommended, as none of the available radio translucent materials reach the required SG. In conclusion, increase of SG was fundamental to optimize bolus retention. Medium-sized boluses (10 to 15 mL; SG 5.8 to 4.9) for early administration and efficient retention in adult goats could be produced, thereby addressing the problem of using proper boluses for goat identification.

Readability of visual and electronic leg tags versus rumen boluses and electronic ear tags for the permanent identification of dairy goats.

Murciano-Granadina dairy goats (n=220) were used to assess the performance of visual and electronic identification devices: 1) leg tags (LT) on the shank of the right hind leg (metatarsus) consisting of plastic bands (181 × 39mm, 21g; n=220) printed with a 3-digit code and closed with 2 types of electronic button tags (ET1, 3.9 g, 26 mm o.d., n=90; ET2, 5.5 g, 25 mm o.d., n=130); 2) electronic rumen boluses (RB, 75 g, 68 × 21 mm, n=220) containing 32 × 3.8 mm transponders; 3) electronic ear tags (EE, button-button, 4.8 g, 24 mm, n=47); and 4) visual plastic ear tags (VE, flag-button, 4.2 g, 40 × 38 mm, n=220). The shank circumference of 47 replacement kids (5 to 6 mo of age) and 103 adult goats was measured to evaluate the proper circumference for fastened LT. Goats were identified with RB and VE before the experiment. Time for leg tagging, reading, and data recording with a handheld transceiver was measured. Readability [(read/readable) × 100] was monitored for 1 yr with goats restrained in the milking parlor. Reading time and errors of RB and ET2 in the milking parlor using the handheld transceiver were recorded. Shank circumference of kids (70±1 mm) was 79.5% of that in adult goats (88±1 mm), thus LT (107±1 mm inner circumference) were only applied to adult goats as they were inadequate for 6-mo-old kids. Time for leg tagging and data recording was 53±3 s. At 1 yr, readability of RB was 96.5%. No LT losses occurred and all were visually readable, although 3 (1.5%) had to be removed due to limping, leading to a final LT retention of 98.5%. Moreover, 7 (3.6%) LT were found open and electronically unreadable. Readability of button transponders, excluding removed LT, was 93.6% (3 lost and 2 unreadable) for ET1, and 98.3% (2 lost) for ET2. Readability was 95.7 and 97.0% in EE and VE ear tags, respectively. Only LT and ET1 readabilities differed. Reading time and reading errors (0.3 vs. 0%) in the milking parlor were greater for RB (61.2s) than for ET2 (45.9s). In conclusion, LT were not adequate for the identification of goat kids under 6 mo of age. Only LT with ET2 transponders met International Committee for Animal Recording requirements for official identification of adult goats (readability >98%) under the conditions of this experiment.

Long-term performance of visual and electronic identification devices in dairy goats.

Dairy goat kids born during a 3-yr period (n = 97) and their mothers (n = 29) were used for a long-term evaluation of the performance of 9 types of identification (ID) devices. Kids wore multiple ID devices: visual ear tags (V1, tip-tag, n = 47; V2, official, n = 50), electronic ear tags (E1, button-button, n = 46; E2, flag-button, n = 46), electronic rumen boluses (B1, mini-bolus 14 g, n = 92; B2, mini-bolus 20 g, n = 28; B3, standard bolus 75 g, n = 34) and glass-encapsulated transponders injected in the forefeet (T1, 15 mm, n = 75; T2, 12 mm, n = 100). Visual ear tags were applied at birth and removed in yearlings, whereas electronic ear tags were applied after bolusing with B1 (6.7 kg BW and 30 d, on average); B2 were administered in the event of a B1 loss, and B3 in case of a B2 loss and in goat does. At d 60 of age, kids were allocated into 2 groups to evaluate the effects of rearing system on ID. Treatments were: weaned (n = 46), and not weaned (n = 46) where kids suckled a milk substitute until d 150. Readability of ID devices (read/readable x 100) was monitored from 1 to 3 yr of age, depending on device and year of birth. Long-term readability was analyzed using a nonparametric survival analysis. A total of 3.3% infections and 6.5% tissue reactions were reported for electronic ear tags, but ears were fully healed in yearlings. Weaning numerically reduced B1 losses at d 150 (weaned, 84.8% vs. not weaned, 73.3%). Readability of visual ear tags in yearlings (V1, 82.9%; V2, 94.0%) was lower than for electronic ear tags (E1 and E2, 100%). Mini-bolus readability in yearlings did not differ by type (B1, 71.4%; B2, 84.6%) or with visual ear tags. No effect of inject type was reported (T1, 92.0%; T2, 96.0%). Survival analysis after yr 3 gave the greatest readability value for E1 (100%), which did not differ from B3 (96.8%). The lowest readability was estimated for B1 (66.3%), followed by E2 (79.8%), B2 (81.4%), and T1 (90.4%). In conclusion, button-button electronic ear tags and standard boluses were the more efficient devices under our conditions, their readability values being greater than injects, electronic mini-boluses, and visual and flag-button electronic ear tags. Transponders injected in the forefeet and mini-boluses used here are not recommended in practice. Further research on E1 and B3 electronic devices should be done in a higher number of goats to confirm the current results.

Long- and short-term effects of omitting two weekend milkings on the lactational performance and mammary tight junction permeability of dairy ewes.

The long- and the short-term effects of omitting 2 milkings weekly in early (wk 8 to 14) and mid lactation (wk 15 to 22) were investigated in an experiment conducted with a total of 58 dairy ewes (40 Manchega and 18 Lacaune). Ewes submitted to 2 milking omissions were milked twice daily from Monday to Friday (0800 and 1800 h), and once daily on Saturday and Sunday (1600 and 1400 h, respectively). Individual data were collected for milk yield (weekly), milk composition (biweekly), and somatic cell count (SCC; monthly). Omitting 2 milkings per week in early lactation tended to decrease milk yield in Manchega ewes (-15%), whereas no effects were observed in Lacaune ewes. Averaged milk composition was not modified by milking omissions in either breed. Milking omissions in late lactation did not affect milk yield and milk composition in either breed. The SCC were unaffected by milking omissions in both breeds and in both stages of lactation. A sample of 22 Manchega and 11 Lacaune ewes were used to evaluate the short-term (daily) effects of the 2 milking omissions per week on milk yield and composition, udder health, and tight junction permeability, both in early lactation (wk 12) and in mid lactation (wk 20). Milking omission decreased milk yield, milk fat, and milk lactose contents on the first omission day in both breeds, with losses being more noticeable in early lactation than in mid lactation. Milk protein content and SCC did not vary by effect of the weekend milking omissions. After restoring the twice-daily milking routine on Monday, milk yield showed a compensatory increase that was greater in the large-cisterned than in the small-cisterned ewes, which allowed milk yield to return to Friday values in both breeds. Milk fat content increased during Sunday and Monday, reestablishing Friday values thereafter in both breeds. Weekend milking omissions in early lactation caused tight junction leakiness in both breeds, but mammary epithelia adapted to extended milking intervals when applied successively, recovering their tight state after milking. In mid lactation, the mammary tight junction showed leakiness only in Manchega ewes. In conclusion, 2 milkings per week could be omitted with no negative effects on milk yield, milk composition, and milk SCC values in large-cisterned dairy ewes, as observed in Lacaune and large-cisterned Manchega ewes. Losses in milk yield could be reduced if milking omissions were done from mid lactation in small-cisterned ewes.

Response to lactation induction differs by season of year and breed of dairy ewes.

Lactation artificially induced (ART) by steroid hormones and natural lactation (NAT) after lambing were compared in 2 dairy sheep breeds (Manchega and Lacaune) in 2 experiments conducted during winter and spring. In experiment 1, ART ewes (14 Manchega and 9 Lacaune) were induced into lactation in winter by the standard protocol, which consisted of s.c. injections of estradiol and progesterone administered in 2 portions daily from d 1 to 7. Hydrocortisone acetate was injected s.c. daily on d 18 to 20. Milking was initiated on d 21 and continued for 13 wk. A similar group of NAT ewes was selected for the contemporary comparison of NAT vs. ART lactation. All Lacaune ewes, but only 3 of the 14 Manchega ewes (21%), were successfully induced into lactation. Despite the successful induction of lactation in Lacaune ewes, milk yield was much lower than that obtained in NAT lactation (1.23 +/- 0.14 vs. 2.51 +/- 0.15 L/ d). Milk composition from wk 5 to 13 did not differ between groups, except for whey protein, which was greater in ART than in NAT ewes (1.47 vs. 1.25%). In experiment 2, 19 Manchega ewes were divided into 2 groups and induced into lactation in spring by using the standard induction protocol, similar to that used in experiment 1 (control, n = 9), or the standard protocol modified with bovine somatotropin (bST, 250 mg/ewe on d 11; n = 10). Manchega ewes had an improved response to the standard protocol of lactation induction in spring compared with winter. Milk yield in bST-treated Manchega ewes was 98% greater than that in control ewes (402 +/- 85 vs. 203 +/- 86 mL/d). The use of bST during mammogenesis did not affect milk composition. In conclusion, marked differences between Manchega and Lacaune dairy ewes were observed in their response to lactation induction when using the standard protocol during different photoperiod conditions. The Manchega ewes were unable to establish lactation in winter but were able to do so in spring. The response to lactation induction in dairy ewes seems to be related to their endogenous levels of prolactin and growth hormone, the use of which should be explored more deeply in future research.

Changes in alveolar and cisternal compartments induced by milking interval in the udder of dairy ewes.

The aim of this work was to evaluate the effects of milking interval (4, 8, 12, 16, 20, and 24 h) on cisternal size and milk partitioning (cisternal and alveolar) in the udders of dairy ewes. Twenty-four dairy ewes (Manchega, n = 12; Lacaune, n = 12) were used in a 2-wk experiment during mid-lactation. Cisternal and alveolar milk yields were measured and milk samples from each udder fraction were collected for analysis. Cisternal milk was obtained after i.v. injection of an oxytocin receptor antagonist, and alveolar milk was obtained after i.v. injection of oxytocin. Enlargement of the cisternal compartment due to milking intervals was measured by ultrasonography for each half udder. Volumes of cisternal and alveolar milk differed according to breed, being greater in Lacaune (888 +/- 43 and 338 +/- 25 mL, respectively) than in Manchega ewes (316 +/- 43 and 218 +/- 25 mL, respectively). Alveolar milk increased linearly to 16 h in Manchega and 20 h in Lacaune and remained constant thereafter. Cisternal milk accumulated linearly to 24-h milking intervals in both breeds. Cisternal area (values per udder half) increased as milking interval increased, reaching a plateau at 20 h in Manchega (21 +/- 1 cm(2)) and 16 h in Lacaune (37 +/- 1 cm(2)). Correlation between cisternal area and cisternal milk was the greatest at 8 h (Manchega: r = 0.70 and Lacaune: r = 0.56). Cisternal area correlated with total milk (r = 0.80). Milk fat content varied markedly with milking intervals, increasing in alveolar milk (until 12 h in Manchega, 8.90 +/- 0.18%; and 20 h in Lacaune, 8.67 +/- 0.19%) and decreasing until 24 h in cisternal milk (5.74 +/- 0.29% and 4.85 +/- 0.29%, respectively). Milk protein content increased in alveolar milk until 24 h (Manchega, 6.46 +/- 0.11%; Lacaune, 5.95 +/- 0.11%), but did not vary in cisternal milk. Milk lactose content only decreased at the 24-h milking interval in the cisternal milk of Manchega ewes (4.60 +/- 0.04%). In conclusion, our results suggest that cisterns play an important role in accommodating secreted milk during extended milking intervals. Thus, long milking intervals could be a recommended strategy for large-cisterned dairy sheep. Evidence indicates that ultrasonography provides accurate estimations of udder cistern size and could be used as an indicator for selecting large-cisterned dairy ewes.

Comparison of manual versus semiautomatic milk recording systems in dairy goats.

A total of 24 Murciano-Granadina dairy goats in early-midlactation were used to compare the labor time and data collection efficiency of using manual (M) vs. semiautomated (SA) systems for milk recording. Goats were milked once daily in a 2 x 12 parallel platform, with 6 milking units on each side. The M system used visual identification (ID) by large plastic ear tags, on-paper data recording, and data manually uploaded to a computer. The SA system used electronic ID, automatic ID, manual data recording on reader keyboard, and automatic data uploading to computer by Bluetooth connection. Data were collected for groups of 2 x 12 goats for 15 test days of each system during a period of 70 d. Time data were converted to a decimal scale. No difference in milk recording time between M and SA (1.32 +/- 0.03 and 1.34 +/- 0.03 min/goat, respectively) was observed. Time needed for transferring data to the computer was greater for M when compared with SA (0.20 +/- 0.01 and 0.05 +/- 0.01 min/goat). Overall milk recording time was greater in M than in SA (1.52 +/- 0.04 vs. 1.39 +/- 0.04 min/goat), the latter decreasing with operator training. Time for transferring milk recording data to the computer was 4.81 +/- 0.34 and 1.09 +/- 0.10 min for M and SA groups of 24 goats, respectively, but only increased by 0.19 min in SA for each additional 24 goats. No difference in errors of data acquisition was detected between M and SA systems during milk recording (0.6%), but an additional 1.1% error was found in the M system during data uploading. Predicted differences between M and SA increased with the number of goats processed on the test-day. Reduction in labor time cost ranged from euro0.5 to 12.9 (US$0.7 to 17.4) per milk recording, according to number of goats from 24 to 480 goats and accounted for 40% of the electronic ID costs. In conclusion, electronic ID was more efficient for labor costs and resulted in fewer data errors, the benefit being greater with trained operators and larger goat herds.

Effect of milking interval on milk secretion and mammary tight junction permeability in dairy ewes.

Twenty-four lactating ewes (Manchega, n = 12; Lacaune, n = 12) in mid lactation were used to assess the short-term effects of different machine milking intervals (4, 8, 12, 16, 20, and 24 h) on milk yield, milk composition, and tight junction (TJ) permeability of mammary epithelia. Milk samples were analyzed for chemical composition, somatic cell count (SCC), and plasmin activity. Plasma lactose, and milk Na and K concentrations were used as indicators of TJ permeability. Milk accumulated linearly for up to 24 h, showing a different rate according to the milk yield of the breed (Manchega, 38 mL/h; Lacaune, 87 mL/h). Milking interval affected milk fat content, which decreased markedly from 4 to 24 h in both breeds, but no differences were observed in milk protein content. The milk contents of casein, true protein, lactose, and total solids also varied according to milking interval. Values of SCC did not vary by breed (175 x 10(3) cells/mL, on average), showing the lowest log(10) values for the 4-and 24-h milking intervals in both breeds. Plasmin activity in milk increased with milking interval until 20 h of udder filling in both breeds, and was poorly but positively correlated with SCC content (r = 0.39). Plasma lactose increased dramatically after 20 h of milk accumulation, indicating enhanced permeability of mammary TJ. As a result, an increase in Na concentration and in the Na:K ratio, and a decrease in K concentration, were observed in the milk of Manchega ewes. On the contrary, no differences in Na and K concentrations in milk were detected in Lacaune ewes. In conclusion, our results proved that Manchega and Lacaune dairy sheep could maintain high rates of milk secretion during extended milking intervals in the short term, with no effects on udder health and few negative effects on milk yield. Increased TJ permeability, caused by the effect of udder filling, induced changes in milk composition that were more marked in Manchega than in Lacaune ewes.