Relationships between dietary factors and milk urea nitrogen level in goats grazing herbaceous pasture

This investigation aimed to individuate the dietary factors affecting the milk urea nitrogen (MUN) concentration in goats grazing herbaceous pasture and, particularly, to verify the relationship linking the diet crude protein (CP) content to MUN. A total of 205 individual observations regarding dietary and milk variables of 37 Girgentana goats involved in two experiments were used. Goats, averaging 154±14 days in milk and 38.1±5.4 kg of live weight, grazed on swards and received 500 g/d of barley meal. Sward biomass, herbage selected by goats and individual milk yield were measured and sampled weekly. The herbage intake and diet digestibility were estimated by the n-alkane method. Milk urea content was determined by an enzymatic method and transformed in MUN (MUN=urea*0.4665). The MUN concentration (9.7-35.4 mg/dl) was positively correlated with diet CP content (13.7-26.0% of dry matter (DM); r=0.76; P<0.001), pasture allowance (39-151 kg DM/goat; r=0.42; P<0.001), diet net energy for lactation concentration (NEL) (1.5-1.9 Mcal/kg DM; r=0.37; P<0.001) and milk yield (320- 2250 g/d; r=0.25; P<0.001), and negatively related with NDF (18.7-37.4% DM; r=-0.69; P<0.001) and diet digestibility (72.6-92.5%; r=-0.33; P< 0.001). The stepwise selection from dietary variables and milk yield showed dietary CP percentage to be the single variable explaining the most variation in MUN (R2=0.56; P< 0.0001). The other variables entering into the model were diet NDF, 3.5% fat-corrected milk (FCM), DM intake and NDF intake (total R2=0.66). Including the CP/NEL and CP/NDF ratios of diet in the stepwise regression model, the CP/NDF ratio alone explained 60.1% of MUN variability, followed by barley proportion in the diet, FCM and diet CP concentration, absorbing an extra 4.6% of MUN variability. A linear regression, fitting mean feeding treatment per time data of MUN and dietary CP concentration (n=28)[CP(% of DM)=6.91±1.42+0.61±0.06*MUN (mg/dl); R²=0.79; P<0.0001], suggests that MUN could be used for predicting the CP content of the diet, as a tool for developing feeding strategies aimed at balancing the rations of grazing goats through adequate supplementation. Further data from experiments on grazing goats in different environmental conditions are required in order to define a more robust relationship by which to predict the dietary CP content by MUN

ASPETTI DELLA PRODUZIONE DEI PICCOLI RUMINANTI CON IMPATTO SULLA SALUTE UMANA

Negli ultimi anni l’attenzione del consumatore si è sempre più orientata verso le caratteristiche nutrizionali degli alimenti. Queste proprietà sono di grande importanza anche per quanto riguarda le produzioni dei piccoli ruminanti. Il presente lavoro ha lo scopo di riassumere i principali risultati emersi dal progetto di ricerca “Aspetti della produzione dei piccoli ruminanti con particolare impatto sulla salute umana”. Sono stati analizzati mediante i metodi descritti in letteratura: 1) i polimorfismi genetici dei biopeptidi del latte dei piccoli ruminanti; 2) le attività di alcuni enzimi della membrana del globulo di grasso e la frazione lipidica del latte ovino; 3) la qualità nutrizionale del latte e del formaggio ovino in relazione all’intensità di pascolamento; 4) le componenti bioattive di siero e scotta residui alla produzione dei formaggi ovi-caprini; 5) la resistenza genetica alle encefalopatie spongiformi trasmissibili e l’efficienza economica e biologica in razze ovine. I risultati ottenuti evidenziano, da svariati punti di vista, numerose potenzialità legate alle produzioni dei piccoli ruminanti e alle loro ricadute sulla salute umana

Body condition score and related productive responces in rabbit does.

A simplified 3-point scale method for in vivo scoring body condition is proposed as an useful and rapid tool to support experimental and on-farm management of nutrition and reproduction of rabbit does. The productive responses of lactating rabbit does scored and inseminated at 11 days post partum (pp) are verified, as well as performance of non-pregnant does scored and re-inseminated at 32 days pp when non-lactating. After their first parturition, 96 New Zealand White rabbit does were checked for 126 days over three successive 42-day reproductive cycles. The body condition scoring was based on feel by hand the loin and the rump for bone protrusions and muscle fullness. The loin was evaluated for poor, intermediate and wide level, the rump for poor and wide level. The body condition was scored “0” with poor loin; “1” with intermediate loin and poor rump; “2” with intermediate and wide loin and wide rump. The highest fertility was obtained with intermediate body condition score (BCS) for both lactating (52.0, 84.9 and 58.6% for BCS 0, 1 and 2; P<0.001) and non-lactating does (53.1, 84.4 and 64.5% for BCS 0, 1 and 2; P<0.05), indicating the negative effect of poor or excessive body fatness. A poor BCS led to lower litter size at birth in lactating (7.2, 8.2 and 8.3 for BCS 0, 1 and 2) and non-lactating does (8.4, 11.1 and 9.6 for BCS 0, 1 and 2; P<0.05), and higher losses of kits from day 1 to 11 of nursing (10.3, 2.2 and 4.5% for BCS 0, 1 and 2; P<0.001). The main part of does culled for infertility (44.4%) or death (46.7%) showed the BCS 2. When lactating does resulted nonpregnant at an 11-day artificial insemination (AI), their frequency in the BCS 2 showed a higher increase from parturition to AI (from 30.8 to 52.2%) than they were pregnant (from 26.8 to 37.7%). The lactating does that were non-lactating in the previous cycle showed a higher incidence at BCS 2 (54.8%) than they were lactating (43.8%) or nulliparous (39.6%). These latter indications suggest that failures in fertility at 11-day AI and culling rate are imputable more to the excessive body fatness of does than to their poor body condition

Jennet milk production during the lactation in a Sicilian farming system

In Italy, the interest for jennet milk production has recently developed. An 18-month-long experiment was carried out on a jennet farm near Milo (CT), where 24 jennets, which derived from the Ragusana breed, were tested for milk yield and composition over an entire lactation period. The jennets were fed with hay and concentrate in a large paddock. From the 28th post-foaling day to the end of the lactation, the jennets were machine-milked twice a day with an in-between milking interval of 5 h. The milk amount from each jennet was recorded every 3 weeks and individual samples were collected and analyzed for fat, protein, casein, non-proteic nitrogen, lactose and somatic cell count. This study showed that jennets at Sicilian latitudes are not seasonal polyestrous. The daily milk yield, the length of lactation and the milk characteristics varied depending on the foaling season. The total average milk production was 490636 kg in 295612 post-foaling days, considering two milking records per day. During the lactation, milk yield decreased constantly from 1.98 to 1.28 kg/jennet per day. When looking at the jennet milk quality during lactation, the percentage of fat and protein decreased, while the lactose percentage increased, according to a tendency apparently unique for equines when compared to the ruminants. When looking at the productive season, spring generally gave the best qualitative and quantitative results. Based on these results, jennet milk yield and quality could be improved; furthermore, jennet milk production may turn out to be a profitable business