| Abstract | Kao rezultat dugogodišnje selekcije visokomliječnih koza radi povećanja proizvodnje
mlijeka, sve je zamjetnije narušavanje morfologije njihova vimena, što nerijetko rezultira
narušenim muznim odlikama koza s posljedičnom upalom vimena, odnosno smanjenjem
proizvodnje i promijenjenim kemijskim sastavom mlijeka. Cilj istraživanja bio je, stoga,
utvrditi međupovezanost morfologije vimena, proizvodnje i kemijskog sastava mlijeka te
zdravlja vimena alpina koza, kao nazastupljenije mliječne pasmine koza u Hrvatskoj.
Istraživanjem je bilo obuhvaćeno 139 strojno muzenih i zdravih (bez uočenih znakova
kliničkog mastitisa) alpina koza, držanih u istom stadu (slobodnom od artritis encefalitisa) i
podređenih identičnoj tehnologiji uzgoja/proizvodnje. Tijekom istraživane laktacije (od
odbića do zasušenja) u navedenom su stadu provedene kontrole mliječnosti (AT4 metoda)
i redovita mjesečna prikupljanja pojedinačnih uzoraka mlijeka radi utvrđivanja njihova
kemijskog sastava. Od svake su koze pri prvoj, četvrtoj i sedmoj kontroli mliječnosti uzeta
po dva uzorka mlijeka (po jedan iz lijeve, odnosno desne polovice vimena) radi određivanja
broja somatskih stanica (BSS), odnosno po dva uzorka u svrhu mikrobiološke pretrage
mlijeka te su vizualnom prosudbom i mjerenjem utvrđene morfološke odlike vimena
istraživanih koza. Utvrđeno je postojanje dvaju (podjednako zastupljenih) oblika vimena, i
to: kruškolik (51,8% istraživanih koza) i ovalan oblik vimena (48,2% koza). U većine (56%)
koza utvrđeno je postojanje sisa ljevkastog oblika, dok je sise cilindričnog oblika imalo 28%,
a sise oblika boce 16% istraživanih koza. Prosječni opseg vimena alpina koza bio je 51,19
cm, širina vimena 13,67 cm, dubina vimena 18,85 cm, udaljenost između vrhova sisa 10,95
cm, kut sisa 39,15, duljina sisa 5,45 i širina sisa 3,45 cm. Utvrđen je značajan utjecaj
redoslijeda i stadija laktacije i broja ojarene jaradi u leglu na većinu analiziranih morfoloških
odlika vimena, dok su dubina i širina vimena te veličina sisa bile pozitivno povezane s
utvrđenim pokazateljima tjelesne razvijenosti koza (dubina prsa, obujam prsiju i tjelesna
masa). Istraživane koze su tijekom prosječnog trajanja laktacije od 294,7 dana proizvele
898,9 kg mlijeka, odnosno prosječno dnevno 2,98 kg mlijeka Istraživanjem nisu utvrđene
značajne razlike u proizvodnji i prosječnom kemijskom sastavu mlijeka između koza
različitih oblika vimena. Najviše mlijeka su proizvele koze sa sisama u obliku boce, odnosno
značajno više nego koze sa ljevkastim sisama. Pritom su sise oblika boce bile značajno
veće te postavljene horizontalnije i s većom udaljenošću jedna od druge u odnosu na sise
drugačijih oblika. Utvrđena je značajna linearna regresija između većine utvđenih mjera
vimena (P<0,001) i sisa (P<0,05) i laktacijske proizvodnje mlijeka, dok su najznačajniji
pokazatelji miječnosti koza bili opseg, dubina i širina vimena (R2=0,23-0,35). Značajno veća
(P<0,05) učestalost intramamarnih infekcija je dijagnosticirana u jedinki ovalnog oblika
vimena nego u jedinki tzv. kruškolikog oblika vimena (17,9:12,5%), a ujedno i veći (P<0,05)
geometrijski prosjek BSS (663x103 : 482x103/mL). Utvrđene su značajne (P<0,05) razlike u
BSS, kao i u učestalosti intramamarnih infekcija (P<0,05) s obzirom na utvrđeni oblik sisa,
pri čemu je u koza sa sisama u obliku boce utvrđena najveća učestalost intramamarnih
infekcija, kao i najveći BSS u mlijeku. Većina morfoloških odlika vimena bila je u značajnoj
korelaciji s BSS te je s povećanjem dubine vimena i veličine sisa, kao i smanjenjem kuta
sisa i udaljenosti između vrhova sisa utvrđeno smanjenje BSS, što se može povezati i sa
smanjenjem udaljenosti sisa od tla. Duljina sisa bila je statistički najznačajniji procjenitelj
(P=0,0548) nastanka infekcije mliječne žlijezde, a najveća učestalost intramamarnih
infekcija je uočena u koza sa najdužim sisama (>6,5 cm), dok je (u pogledu zdravlja vimena)
najoptimalnija duljina sisa 5,5 - 6 cm. Istraživanjem dobivene spoznaje mogu doprinijeti
uvođenju morfologije vimena u provedbu uzgojnih programa za alpina koze u cilju daljnjeg
povećanja mliječnosti, ali bez nužno negativnog odražavanja na zdravlje njihova vimena. |
| Abstract (english) | In herds of high-producing dairy goats, as a result of long-term selection to increase milk
yield, a deterioration in udder morphology is increasingly noticeable (e.g. large and drooping
udders, horizontally placed teats, large teats unsuitable for machine milking, teats close to
the ground, etc.), which not only affects milking characteristics, but also has a negative
impact on udder health. Namely, it is known that mastitis is the most common and at the
same time the most expensive disease in dairy goat herds, i.e. an important factor for the
production longevity of dairy goats. Related to this, in recent scientific literature, certain
morphological characteristics of goat udders and teats are increasingly cited as factors for
premature excretion, especially in high-producing genotypes. Considering that goat milk
production in Croatia is based on high-producing breeds, the most numerous of which is
Alpine, the aim of the study was to confirm the hypothesis of the connection of udder
morphology with milk production and chemical composition, i.e. the association of certain
udder morphological characteristics with indicators of mammary gland health in Alpine
goats. The study included 139 purebred and machine milked Alpine goats of different
lactation orders. The selected livestock units had symmetrically developed udders with no
visible signs of mastitis. The same breeding and production technology (feeding, housing,
method and number of daily milkings, etc.) was applied in the studied livestock units kept in
the same herd. Goats were kept indoors throughout the year, which allowed the monitoring
of individual livestock units, especially with regard to the occurrence of possible diseases
or the monitoring of individual reproductive phases. During the milking period, regular
monthly milking controls of goats were carried out using the AT4 method, by which also
individual milk samples were collected to determine chemical composition. The
morphological characteristics of the udder were determined (assessments of the goat’s
udder and teats according to the shape and measurement of the morphological
characteristics) once in the early, middle, and late stages of lactation. Also, during the
aforementioned milking controls, one milk sample was taken from each half of the udder for
microbiological tests and determination of somatic cell count (SCC). Statistical analysis was
performed using SAS V 9.4 software package (SAS STAT, 2013). The presence of two
udder types was found in Alpine goats: the pear-shaped udder, characteristic of highproducing
goats, was found in 51.8% of Alpine goats, and the oval shape in 48.2%. The
average udder circumference was 51.19 cm, width 13.67 cm, and depth 18.85 cm. Majority
(56%) of the goats surveyed had funnel-shaped teats. 28.1% of the goats had cylindrical
teats, while 16% of the goats had teats with the so-called bottle-shaped tip. On average,
the bottle-shaped teats were largest in terms of length and width, and also the most vertical
(the smallest average teat angle) compared to the other two teat types. The morphological
characteristics of the udder increased with the progress of lactation. In addition, significantly
larger circumference and depth of the udder and length and width of the teats were
observed in goats with a larger litter compared to goats with one kid in the litter. In terms of
chemical composition of milk, the milk of goats in the first lactation and in the earlier stages
of lactation was the richest in terms of dry matter content, dry matter without fat, milk fat,
and protein content. Higher proportions of chemical indicators were also found in the milk
of goats with one kid, which is a consequence of less frequent udder emptying and lower
level of production of the total amount of milk. The content of all analysed ingredients,
except lactose, was lower with higher daily and lactation milk production. The highest SCC
in the middle stage of lactation was found in healthy goats. While udder shape had no effect
on average milk production, chemical composition, and duration of lactation, a significant
positive correlation was found between other morphological characteristics of the udder and
milk production and SCC. Goats with the most developed udder, bottle-shaped teats, and
larger dimensions achieved the highest average daily and lactation milk production, and
longer and wider breasts and an oval shape of the udder were associated with higher SCC
and higher prevalence of subclinical udder inflammation. A higher prevalence of subclinical
mastitis was found in goats with one kid than in goats with more kids.
The results of this study indicate the importance of udder morphology as a factor in udder
health, chemical composition, and milk production. Knowledge of morphological traits can
contribute to the development of a separate breeding program for the Alpine goat, with the
aim of genetically improving of udder morphology to increase milk yield. |
